4,248 results on '"ACTIVE oxygen in the body"'
Search Results
2. Exercise-Induced Hypoxemia in Juvenile Thyroid Carcinoma With Lung Metastases.
- Author
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Segerer, Florian J., Biko, Johannes, Reiners, Christoph, Wirth, Clemens, and Hebestreit, Helge
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CANCER treatment ,PULMONARY fibrosis ,HYPOVENTILATION ,LUNG analysis ,IODINE radioisotopes ,ACTIVE oxygen in the body ,AEROBIC exercises ,AGE distribution ,HYPOXEMIA ,CARDIOPULMONARY system ,COMPUTED tomography ,EXERCISE tests ,HYPOTHYROIDISM ,LUNG tumors ,METASTASIS ,PULMONARY gas exchange ,RESPIRATORY measurements ,PULMONARY function tests ,SEX distribution ,THYROID gland tumors ,VENTILATION-perfusion ratio ,RETROSPECTIVE studies ,DIAGNOSIS ,THERAPEUTICS - Abstract
Purpose: Exercise-induced arterial hypoxemia (EIAH) has been reported in patients with juvenile thyroid cancer treated with radioiodine for lung metastases. This retrospective study tested the hypothesis that EIAH is due to ventilation-perfusion-mismatch in this rare pulmonary condition. Methods: 50 patients (age 13-23 years) treated for juvenile thyroid carcinoma and lung metastasis with
131 I and 24 controls with thyroid cancer but without lung metastases and prior131 I-treatment were assessed in a state of acute hypothyroidism by computed tomography of the lungs, pulmonary function testing, cardiopulmonary exercise test with measurements of gas exchange, oxygen saturation, alveolar-arterial difference in pO2 (p(A-a)O2 ) and pCO2 (p(ET-a)CO2 ). Results: 10 of the 50 patients with lung metastases showed EIAH. They had more pronounced pulmonary fibrosis on computed tomography, a widened p(A-a)O2 , and p(ET-a)CO2 , a lower DVE/DVCO2 -slope, a lower respiratory rate and no increased dead space ventilation. A more pronounced EIAH was associated with male gender, younger age, lower diffusion capacity, higher p(ET-a)CO2 during exercise and a higher peak exercise tidal volume over vital capacity ratio. Conclusion: EIAH in patients with thyroid carcinoma and pulmonary metastases is not related to ventilation-perfusion mismatch but to alveolar hypoventilation, possibly related to an increased work of breathing with pulmonary fibrosis. [ABSTRACT FROM AUTHOR]- Published
- 2017
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3. Effects of Ultratrail Running on Skeletal-Muscle Oxygenation Dynamics.
- Author
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Vernillo, Gianluca, Brighenti, Alfredo, Limonta, Eloísa, Trabucchi, Pietro, Malatesta, Davide, Millet, Grégoire P., and Schena, Federico
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ACTIVE oxygen in the body ,EXERCISE physiology ,LONGITUDINAL method ,MICROCIRCULATION ,PROBABILITY theory ,RUNNING ,EXTREME sports ,QUADRICEPS muscle ,OXYGEN consumption - Abstract
Purpose: To quantify changes in skeletal-tnuscle oxygenation and pulmonary O
2 uptake (...O2 ) after an extreme ultrarail running bout. Methods: Before (PRE) and after (POST) the race (330-km, 24000 D±), profiles of vastus lateralis muscle oxygenation (ie, oxyhemoglobin [O2 Hb], deoxyhemoglobin [HHb], and tissue oxygenation index [TOI]) and ...O2 were determined in 14 athletes (EXP) and 12 control adults (CON) during two 4-min constant-load cycling bouts at power outputs of 1 (p1) and 1.5 (p1.5) W/kg performed in randomized order. Results: At POST, normalized [HHb] values increased (p1, +38.0%; p1.5, +27.9%; P < .05), while normalized [O2 Hb] (p1, -20.4%; p1 .5, -14.4%; P < .05) and TOI (p1, -17.0%; p1.5, -17.7%; P < .05) decreased in EXP. ...O2 values were similar (P > 0.05). An "overshoot" in normalized [HHb]:...O2 was observed, although the ircrease was significant only during p1.5 (+58.7%, P = .003). No difference in the aforementioned variables was noted in CON (P > .05). Conclusions: The concentric and, particularly, the eccentric loads characterizing this extreme ultratrail-running bout may have led to variations in muscle structure and function, increasing the local muscle deoxygenation profile and the imbalance between O2 delivery to working muscles and muscle O2 consumption. This highlights the importance of incorporating graded training, particularly downhill bouts, to reduce the negative influence of concentric and severe eccentric loads to the micrccirculatory function and to enhance the ability of runners to sustain such loading. [ABSTRACT FROM AUTHOR]- Published
- 2017
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4. Near-Infrared Spectroscopy: More Accurate Than Heart Rate for Monitoring Intensity in Running in Hilly Terrain.
- Author
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Born, Dennis-Peter, Stöggl, Thomas, Swarén, Mikael, and Björklund, Glenn
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ACTIVE oxygen in the body ,COMPARATIVE studies ,HEART beat ,NEAR infrared spectroscopy ,PROBABILITY theory ,PULMONARY gas exchange ,RUNNING ,OXYGEN consumption ,EXERCISE intensity - Abstract
Purpose: To investigate the cardiorespiratory and metabolic response of trail running and evaluate whether heart rate (HR) adequately reflects the exercise intensity or if the tissue-saturation index (TSI) could provide a more accurate measure during running in hilly terrain. Methods: Seventeen competitive runners (4 women, ...O
2 max, 55 ± 6 mL ⋅ kg-1 ⋅ min-1 ; 13 men, ...O2 max, 68 ± 6 mL ⋅ kg-1 ⋅ min-1 ) performed a time trial on an off-road trail course. The course was made up of 2 laps covering a total distance of 7 km and included 6 steep uphill and downhill sections with an elevation gain of 486 m. All runners were equipped with a portable breath-by-breath gas analyzer, HR belt, global positioning system receiver, and near-infrared spectroscopy (NIRS) device to measure the TSI. Results: During the trail run, the exercise intensity in the uphill and downhill sections was 94% ± 2% and 91% ± 3% of maximal heart rate, respectively, and 84% ± 8% and 68% ± 7% of ...O2 max, respectively. The oxygen uptake (...O2 ) increased in the uphill sections and decreased in the downhill sections (P < .01). Although HR was unaffected by the altering slope conditions, the TSI was inversely correlated to the changes in ...O2 (r= -.70, P < .05). Conclusions: HR was unaffected by the continuously changing exercise intensity; however, TSI reflected the alternations in ...O2 . Recently used exclusively for scientific purposes, this NIRS-based variable may offer a more accurate alternative than HR to monitor running intensity in the future, especially for training and competition in hilly terrain. [ABSTRACT FROM AUTHOR]- Published
- 2017
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5. No Improved Performance With Repeated-Sprint Training in Hypoxia Versus Normoxia: A Double-Blind and Crossover Study.
- Author
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Montero, David and Lundby, Carsten
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QUADRICEPS muscle physiology ,ACTIVE oxygen in the body ,ALTITUDES ,ANALYSIS of variance ,ANTHROPOMETRY ,CROSSOVER trials ,CYCLING ,EXERCISE physiology ,EXERCISE tests ,HEMOGLOBINS ,NEAR infrared spectroscopy ,OXIMETRY ,PERFUSION ,PROBABILITY theory ,RESEARCH funding ,STATISTICAL sampling ,STATISTICAL hypothesis testing ,STATISTICS ,T-test (Statistics) ,PULSE oximeters ,DATA analysis ,ERGOGENIC aids ,PHYSICAL training & conditioning ,RANDOMIZED controlled trials ,PRE-tests & post-tests ,REPEATED measures design ,OXYGEN consumption ,ERGOMETRY ,BLIND experiment ,EXERCISE intensity ,DATA analysis software ,DESCRIPTIVE statistics - Abstract
Context: Few recent studies indicate that short-term repeated-sprint (RS) training in hypoxia (RSH) improves RS performance compared with identical training under normoxic conditions (RSN) in endurance-trained subjects. Purpose: To determine the effects of RSH against RSN on RS performance under normoxic and moderate hypoxic conditions, using a randomized, doubleblind, crossover experimental design. Methods: Fifteen endurance-trained male subjects (age 25 ± 4 y) performed 4 wk of RS training (3 sessions/wk) in normobaric hypoxia (RSH, FiO
2 = 13.8%) and normoxia (RSN, FiO2 = 20.9%) in a crossover manner. Before and after completion of training, RS tests were performed on a cycle ergometer with no prior exercise (RSNE ), after an incremental exercise test (RSIE ), and after a time-trial test (RSTT ) in normoxia and hypoxia. Results: Peak power outputs at the incremental exercise test and time-trial performance were unaltered by RSH in normoxia and hypoxia. RS performance was generally enhanced by RSH, as well as RSN, but there were no additional effects of RSH over RSN on peak and mean sprint power output and the number of repeated sprints performed in the RSNE , RSIE , and RSTT trials under normoxic and hypoxic conditions. Conclusions: The present double-blind crossover study indicates that RSH does not improve RS performance compared with RSN in normoxic and hypoxic conditions in endurance-trained subjects. Therefore, caution should be exercised when proposing RSH as an advantageous method to improve exercise performance. [ABSTRACT FROM AUTHOR]- Published
- 2017
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6. Psychophysiological Responses to Repeated-Sprint Training in Normobaric Hypoxia and Normoxia.
- Author
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Brocherie, Franck, Millet, Grégoire P., and Girard, Olivier
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ACCLIMATIZATION ,ACTIVE oxygen in the body ,ANALYSIS of variance ,HYPOXEMIA ,ATHLETIC ability ,COMPARATIVE studies ,DYSPNEA ,ECOLOGY ,EXERCISE ,HEART beat ,HEMOGLOBINS ,HOCKEY ,LEG ,OXYGEN ,PHYSICAL therapy ,PROBABILITY theory ,PSYCHOPHYSIOLOGY ,RESEARCH funding ,RESPIRATION ,RUNNING ,STATISTICAL sampling ,STATISTICS ,PHYSIOLOGICAL stress ,TIME ,DATA analysis ,ELITE athletes ,REPEATED measures design ,OXYGEN consumption ,DATA analysis software ,DESCRIPTIVE statistics ,ONE-way analysis of variance - Abstract
Purpose: To compare psychophysiological responses to 6 repeated-sprint sessions in normobaric hypoxia (RSH) and normoxia (RSN) in team-sport athletes during a 2-wk "live high-train low" training camp. Methods: While residing under normobaric hypoxia (≥14 h/d, FiO
2 14.5-14.2%), 23 lowland elite field hockey players performed, in addition to their usual training, 6 sessions (4 x 5 x 5-s maximal sprints, 25-s passive recovery, 5 min rest) under either RSH (FiO2 ~14.5%) or RSN (FiO2 21%). Sprint 1 and 5 times, physiological strain (heart rate [HR], arterial oxyhemoglobin saturation [SpO2 ]), and perceptual responses (overall peripheral discomfort, difficulty breathing, and lower-limb discomfort) were monitored. Results: During the 1st session, HR increased across sets (P < .001) independently of the conditions, while SpO2 was globally lower (P < .001) for RSH (averaged value: 91.9% ± 1.2%) vs RSN (96.9% ± 0.6%). Thereafter, SpO2 and HR remained similar across sessions for each condition. While 1st-sprint time remained similar, last-sprint time and fatigue index significantly decreased across sets (P < .01) and sessions (P < .05) but not between conditions. Ratings of overall perceived discomfort, difficulty breathing, and lower-limb discomfort were higher (P < .05) in RSH vs RSN at the 1st session. During subsequent sessions, values for overall perceived discomfort (time [P < .001] and condition [P < .05] effects), difficulty breathing (time effect; P < .001), and lower-limb discomfort (condition [P < .001] and interaction [P < .05] effects) decreased to a larger extent in RSH vs RSN. Conclusion: Despite higher hypoxia-induced physiological and perceptual strain during the 1st session, perceptual responses improved thereafter in RSH so as not to differ from RSN. This indicates an effective acclimation and tolerance to this innovative training. [ABSTRACT FROM AUTHOR]- Published
- 2017
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7. Modulation of Oxidative Stress in Heart Disease
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Sajal Chakraborti, Naranjan S. Dhalla, Madhu Dikshit, Nirmal K. Ganguly, Sajal Chakraborti, Naranjan S. Dhalla, Madhu Dikshit, and Nirmal K. Ganguly
- Subjects
- Heart--Pathophysiology, Active oxygen in the body
- Abstract
This book highlights the multifaceted roles of Reactive Oxygen Species (ROS) in modulating normal cellular and molecular mechanisms during the development of different types of heart disease. Each chapter in the book deals with the role that altered redox homeostasis plays in the pathophysiology of heart disease. In addition, the book explains how reactive oxidant species interact with their targets and provides novel strategies for attenuating oxidative stress-induced types of heart disease.The book not only covers ROS-induced response in heart disease at the cellular level, but also demonstrates that an imbalance of redox states has its roots in our genes, and explains the ways gene expression is regulated. In turn, it reviews potential sources of ROS, their pathological effects on the heart, and potential sites for therapeutic interventions.
- Published
- 2019
8. Effect of Acute Dietary Nitrate Consumption on Oxygen Consumption During Submaximal Exercise in Hypobaric Hypoxia.
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Carriker, Colin R., Mermier, Christine M., VanDusseldorp, Trisha A., Johnson, Kelly E., Beltz, Nicholas M., Vaughan, Roger A., McCormick, James J., Cole, Nathan H., Witt, Christopher C., and Gibson, Ann L.
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HYPOXEMIA , *PHYSIOLOGICAL effects of nitrates , *EXERCISE , *OXYGEN , *METABOLISM , *ACTIVE oxygen in the body , *ALTITUDES , *ANALYSIS of variance , *CROSSOVER trials , *CYCLING , *DIETARY supplements , *EXERCISE physiology , *LACTATES , *NITRATES , *NITRITES , *PLACEBOS , *PROBABILITY theory , *PULMONARY gas exchange , *RESEARCH funding , *STATISTICS , *DATA analysis , *RANDOMIZED controlled trials , *REPEATED measures design , *OXYGEN consumption , *ERGOMETRY , *BLIND experiment , *EXERCISE intensity , *DATA analysis software - Abstract
Reduced partial pressure of oxygen impairs exercise performance at altitude. Acute nitrate supplementation, at sea level, may reduce oxygen cost during submaximal exercise in hypobaric hypoxia. Therefore, we investigated the metabolic response during exercise at altitude following acute nitrate consumption. Ten well-trained (61.0 ± 7.4 ml/kg/min) males (age 28 ± 7 yr) completed 3 experimental trials (Tl, T2, T3). T1 included baseline demographics, a maximal aerobic capacity test (VO2max) and five submaximal intensity cycling determination bouts at an elevation of 1600 m. A 4-day dietary washout, minimizing consumption of nitrate-rich foods, preceded T2 and T3. In a randomized, double-blind, placebo-controlled, crossover fashion, subjects consumed either a nitrate-depleted beetroot juice (PL) or -12.8 mmol nitrate rich (NR) beverage 2.5 hr before T2 and T3. Exercise at 3500 m (T2 and T3) via hypobaric hypoxia consisted of a 5-min warm-up (25% of normobaric V02max) and four 5-min cycling bouts (40, 50, 60, 70% of normobaric VO2max) each separated by a 4-min rest period. Cycling RPM and watts for each submaximal bout during T2 and T3 were determined during T1. Preexercise plasma nitrite was elevated following NR consumption compared with PL (1.4 ± 1.2 and 0.7 ± 0.3 uM respectively; p < .05). There was no difference in oxygen consumption (-0.5 ± 1.8, 0.1 ± 1.7, 0.7 ± 2.1, and 1.0 ± 3.0 ml/kg/min) at any intensity (40, 50, 60, 70% of VO2max, respectively) between NR and PL. Further, respiratory exchange ratio, oxygen saturation, heart rate and rating of perceived exertion were not different at any submaximal intensity between NR and PL either. Blood lactate, however, was reduced following NR consumption compared with PL at 40 and 60% of VO2max (p < .0.05). Our findings suggest that acute nitrate supplementation before exercise at 3500 m does not reduce oxygen cost but may reduce blood lactate accumulation at lower intensity workloads. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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9. Effects of Priming and Pacing Strategy on Oxygen-Uptake Kinetics and Cycling Performance.
- Author
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Bailey, Stephen J., Vanhatalo, Anni, Black, Matthew I., DiMenna, Fred J., and Jones, Andrew M.
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ACTIVE oxygen in the body ,ANALYSIS of variance ,ANTHROPOMETRY ,ATHLETIC ability ,CLINICAL trials ,CROSSOVER trials ,CYCLING ,EXERCISE physiology ,EXERCISE tests ,HEMOGLOBINS ,LACTATES ,NEAR infrared spectroscopy ,PROBABILITY theory ,PULMONARY gas exchange ,STATISTICAL sampling ,STATISTICS ,T-test (Statistics) ,DATA analysis ,WARMUP ,RANDOMIZED controlled trials ,REPEATED measures design ,OXYGEN consumption ,ERGOMETRY ,EXERCISE intensity ,DESCRIPTIVE statistics - Abstract
Purpose: To assess whether combining prior "priming" exercise with an all-out pacing strategy is more effective at improving oxygen-uptake (...O
2 ) kinetics and cycling performance than either intervention administered independently. Methods: Nine men completed target-work cycling performance trials using a self-paced or all-out pacing strategy with or without prior severe-intensity (70%Δ) priming exercise. Breath-by-breath pulmonary VO2 and cycling power output were measured during all trials. Results: Compared with the self-paced unprimed control trial (22 ± 5 s), the VO2 mean response time (MRT) was shorter (...O2 kinetics were faster) with all-out pacing (17 ± 4 s) and priming (17 ± 3 s), with the lowest ...O2 MRT observed when all-out pacing and priming were combined (15 ± 4 s) (P < .05). However, total O2 consumed and end-exercise ...O2 were only higher than the control condition in the primed trials (P < .05). Similarly, cycling performance was improved compared with control (98 ±11 s) in the self-paced primed (93 ± 8 s) and all-out primed (92 ± 8 s) trials (P < .05) but not the all-out unprimed trial (97 ± 5 s; P > .05). Conclusions: These findings suggest that combining an all-out start with severe-intensity priming exercise additively improves VO2 MRT but not total O2 consumption and cycling performance since these were improved by a similar magnitude in both primed trials relative to the self-paced unprimed control condition. Therefore, these results support the use of priming exercise as a precompetition intervention to improve oxidative metabolism and performance during short-duration high-intensity cycling exercise, independent of the pacing strategy adopted. [ABSTRACT FROM AUTHOR]- Published
- 2016
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10. Cerebral and Muscle Tissue Oxygenation During Incremental Cycling in Male Adolescents Measured by Time-Resolved Near-Infrared Spectroscopy.
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Ganesan, Goutham, Szu-yun Leu, Cerussi, Albert, Tromberg, Bruce, Cooper, Dan M., and Galassetti, Pietro
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BRAIN metabolism ,ACTIVE oxygen in the body ,CONFIDENCE intervals ,STATISTICAL correlation ,CYCLING ,EXERCISE physiology ,HEART beat ,HEMOGLOBINS ,LONGITUDINAL method ,NEAR infrared spectroscopy ,PULMONARY gas exchange ,REGRESSION analysis ,RESEARCH funding ,QUADRICEPS muscle ,OXYGEN consumption ,EXERCISE intensity ,DATA analysis software ,DESCRIPTIVE statistics - Abstract
Near-infrared spectroscopy has long been used to measure tissue-specific O
2 dynamics in exercise, but most published data have used continuous wave devices incapable of quantifying absolute Hemoglobin (Hb) concentrations. We used time-resolved near-infrared spectroscopy to study exercising muscle (Vastus Lateralis, VL) and prefrontal cortex (PPC) Hb oxygenation in 11 young males (15.3 ± 2.1 yrs) performing incremental cycling until exhaustion (peak; VO2 = 42.7 ±6,1 ml/min/kg, mean peak power = 181 ± 38 W). Time-resolved near-infrared spectroscopy measurements of reduced scattering (μs' ) and absorption (μa ) at three wavelengths (759, 796, and 833 nm) were used to calculate concentrations of oxyHb ([HbO2 ]), deoxy Hb ([HbR]), total Hb ([THb]), and O2 saturation (stO2 ). In PFC, significant increases were observed in both [HbO2 ] and [HbR] during intense exercise. PFC stO2 % remained stable until 80% of total exercise time, then dropped (-2.95%, p - .0064). In VL, stO2 % decreased until peak time (-6.8%, p = .01). Segmented linear regression identified thresholds for PFC [HbO2 ], [HbR], VL [THb]. There was a strong correlation between timing of second ven-tilatory threshold and decline in PFC [HbO2 ] (r= .84). These findings show that time-resolved near-infrared spectroscopy can be used to study physiological threshold phenomena in children during maximal exercise, providing insight into tissue specific hemodynamics and metabolism. [ABSTRACT FROM AUTHOR]- Published
- 2016
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11. A Combination of Amino Acids and Caffeine Enhances Sprint Running Capacity in a Hot, Hypoxic Environment.
- Author
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Eaton, Tom R., Potter, Aaron, Billaut, François, Panchuk, Derek, Pyne, David B., Gore, Christopher J., Ting-Ting Chen, McQuade, Leon, and Stepto, Nigel K.
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FATIGUE prevention , *ACTIVE oxygen in the body , *AMINO acids , *HYPOXEMIA , *BLOOD sugar , *CAFFEINE , *CARBON dioxide , *CONFIDENCE intervals , *CROSSOVER trials , *DIETARY supplements , *ECOLOGY , *ELECTROMYOGRAPHY , *EXERCISE tests , *FOOTBALL , *LACTATES , *MUSCLE contraction , *NEAR infrared spectroscopy , *PLACEBOS , *PROBABILITY theory , *RESEARCH funding , *RUNNING , *STATISTICS , *TEMPERATURE , *DATA analysis , *EFFECT sizes (Statistics) , *RANDOMIZED controlled trials , *TEAM sports , *OXYGEN consumption , *DESCRIPTIVE statistics - Abstract
Heat and hypoxia exacerbate central nervous system (CNS) fatigue. We therefore investigated whether essential amino acid (EAA) and caffeine ingestion attenuates CNS fatigue in a simulated team sport-specific running protocol in a hot, hypoxic environment. Subelite male team sport athletes (n = 8) performed a repeat sprint running protocol on a nonmotorized treadmill in an extreme environment on 4 separate occasions. Participants ingested one of four supplements: a double placebo, 3 mg.kg-1 body mass of caffeine + placebo, 2x1 g EAA (Musashi Create)+placebo, or caffeine + EAA before each exercise session using a randomized, double-blind crossover design. Electromyography (EMG) activity and quadriceps evoked responses to magnetic stimulation were assessed from the dominant leg at preexercise, halftime, and postexercise. Central activation ratio (CAR) was used to quantify completeness of quadriceps activation. Oxygenation of the prefrontal cortex was measured via near-infrared spectroscopy. Mean sprint work was higher (M = 174 J, 95% CI [23, 324], p < .05, d = 0.30; effect size, likely beneficial) in the caffeine + EAA condition versus EAAs alone. The decline in EMG activity was less (M = 13%, 95% CI [0, 26]; p < .01, d = 0.58, likely beneficial) in caffeine + EAA versus EAA alone. Similarly, the pre- to postexercise decrement in CAR was significantly less (M = -2.7%, 95% CI [0.4, 5.4]; p < .05, d = 0.50, likely beneficial) when caffeine + EAA were ingested compared with placebo. Cerebral oxygenation was lower (M = -5.6%, 95% CI [1.0, 10.1]; p < .01, d = 0.60, very likely beneficial) in the caffeine + EAA condition compared with LNAA alone. Coingestion of caffeine and EAA appears to maintain muscle activation and central drive, with a small improvement in running performance. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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12. Low Cardiorespiratory Fitness is Partially Linked to Ventilatory Factors in Obese Adolescents.
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Mendelson, Monique, Michallet, Anne-Sophie, Tonini, Julia, Favre-Juvin, Anne, Guinot, Michel, Wuyam, Bernard, and Flore, Patrice
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ACTIVE oxygen in the body ,ANALYSIS of variance ,CARDIOPULMONARY system ,CHI-squared test ,STATISTICAL correlation ,CYCLING ,DYSPNEA ,EXERCISE ,EXERCISE tests ,HEART beat ,LONGITUDINAL method ,CHILDHOOD obesity ,OXIMETRY ,PHYSICAL fitness ,PROBABILITY theory ,PULMONARY gas exchange ,RESPIRATION ,RESPIRATORY measurements ,STATISTICS ,T-test (Statistics) ,PULSE oximeters ,DATA analysis ,AEROBIC capacity ,BODY mass index ,VISUAL analog scale ,REPEATED measures design ,OXYGEN consumption ,ERGOMETRY ,VITAL capacity (Respiration) ,DATA analysis software ,WAIST circumference ,DESCRIPTIVE statistics ,MANN Whitney U Test - Abstract
Aim: To examine the role of ventilatory constraint on cardiorespiratory fitness in obese adolescents. Methods: Thirty obese adolescents performed a maximal incremental cycling exercise and were divided into 2 groups based on maximal oxygen uptake (VO
2peak ): those presenting low (L; n = 15; VO2peak : 72.9 ± 8.6% predicted) or normal (N;B= 15; VO2peak : 113.6 ± 19.2% predicted) cardiorespiratory fitness. Both were compared with a group of healthy controls (C; n = 20; VO2peak : 103.1 ± 11.2% predicted). Ventilatory responses were explored using the flow volume loop method. Results: Cardiorespiratory fitness (VO2peak . in % predicted) was lower in L compared with C and N and was moderately associated with the percent predicted forced vital capacity (FVC) (r = .52; p < .05) in L. At peak exercise, end inspiratory point was lower in L compared with N and C (77.4 ±8.1, 86.4 ± 7.7, and 89.9 ± 7.6% FVC in L, N, and C, respectively; p < .05), suggesting an increased risk of ventilatory constraint in L, although at peak exercise this difference could be attributed to the lower maximal ventilation in L. Conclusion: Forced vital capacity and ventilatory strategy to incremental exercise slightly differed between N and L. These results suggest a modest participation of ventilatory factors to exercise intolerance. [ABSTRACT FROM AUTHOR]- Published
- 2016
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13. Potential of Sestrin2 in the prevention and treatment of chronic diseases.
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Ping Li and Xiao-Qin Ha
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HEAT shock proteins ,NON-communicable diseases ,CHRONIC diseases ,FREE radicals ,ACTIVE oxygen in the body - Abstract
The prevalence and lethality of chronic non-communicable diseases are constantly rising, becoming a global public health problem. The occurrence and development of chronic diseases are closely related to the generation of excessive free radicals and active oxygen in the body, and anti-oxidation will become an effective treatment. Sestrin2 protein, as a new stress protein found in mammals in recent years, has unique advantages in antioxidants, and is expected to become an effective biomarker and therapeutic target for chronic diseases. The following is a review of the regulatory role and mechanism of sestrin2 in chronic diseases in order to provide a reference for the research of other scholars. [ABSTRACT FROM AUTHOR]
- Published
- 2021
14. Superoxide Ion: Volume II (1991) : Chemistry and Biological Implications
- Author
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Igor B. Afanas'ev and Igor B. Afanas'ev
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- Active oxygen in the body, Superoxides--Congresses
- Abstract
The chemical properties of superoxide ion, its biological role, and the role of other oxygen radicals which arise as a result of its transformations are contained in this text. In Volume I the principal reactions of superoxide ion, including protonation reactions with proton donors, nucleophilic reactions with esters, alkyl halides and other compounds, electron transfer reactions with quinones and metal complexes, are described.
- Published
- 2018
15. Acute Beetroot Juice Supplementation Does Not Improve Cycling Performance in Normoxia or Moderate Hypoxia.
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MacLeod, Kristin E., Nugent, Sean F., Barr, Susan I., Koehle, Michael S., Sporer, Benjamin C., and MacInnis, Martin J.
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ACTIVE oxygen in the body , *ALTITUDES , *ANALYSIS of variance , *HYPOXEMIA , *ATHLETIC ability , *BEETS , *BLOOD pressure , *CARDIOPULMONARY system , *STATISTICAL correlation , *CYCLING , *DIETARY supplements , *EXERCISE tests , *HEART beat , *NITRATES , *NITRIC oxide , *PLACEBOS , *RESEARCH funding , *RANDOMIZED controlled trials , *REPEATED measures design , *OXYGEN consumption , *BLIND experiment , *DESCRIPTIVE statistics - Abstract
Beetroot juice (BR) has been shown to lower the oxygen cost of exercise in normoxia and may have similar effects in hypoxia. We investigated the effect of BR on steady-state exercise economy and 10-km time trial (TT) performance in normoxia and moderate hypoxia (simulated altitude: ~2500 m). Eleven trained male cyclists (VO2peak ≥ 60 ml·kg-1min-1) completed four exercise trials. Two hours before exercise, subjects consumed 70 mL BR (~6 mmol nitrate) or placebo (nitrate-depleted BR) in a randomized, double-blind manner. Subjects then completed a 15-min self-selected cycling warm-up, a 15-min steady-state exercise bout at 50% maximum power output, and a 10-km time trial (TT) in either normoxia or hypoxia. Environmental conditions were randomized and single-blind. BR supplementation increased plasma nitrate concentration and fraction of exhaled nitric oxide relative to PL (p < .05 for both comparisons). Economy at 50% power output was similar in hypoxic and normoxic conditions (p > .05), but mean power output was greater in the normoxic TT relative to the hypoxic TT (p < .05). BR did not affect economy, steady-state SpO2, mean power output, or 10-km TT completion time relative to placebo in either normoxia or hypoxia (p > .05 in all comparisons). In conclusion, BR did not lower the oxygen cost of steady-state exercise or improve exercise performance in normoxia or hypoxia in a small sample of well-trained male cyclists. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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16. Whole-Body Cryotherapy's Enhancement of Acute Recovery of Running Performance in Well-Trained Athletes.
- Author
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Kruger, Malte, de Marees, Markus, Dittmar, Karl-Heinrich, Sperlich, Billy, and Mester, Joachim
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PHYSICAL fitness ,EXERCISE ,BODY composition ,QUADRICEPS muscle physiology ,ACTIVE oxygen in the body ,AFFECT (Psychology) ,ANALYSIS of variance ,ANTHROPOMETRY ,ATHLETIC ability ,BODY temperature ,MEDICAL thermometry ,CLINICAL trials ,COLD therapy ,CROSSOVER trials ,EXERCISE physiology ,EXERCISE tests ,HEART rate monitoring ,LACTATES ,NEAR infrared spectroscopy ,PROBABILITY theory ,PSYCHOLOGICAL tests ,QUESTIONNAIRES ,RUNNING ,STATISTICAL sampling ,STATISTICS ,T-test (Statistics) ,DATA analysis ,EFFECT sizes (Statistics) ,TREADMILLS ,COOLDOWN ,SKIN temperature ,BODY mass index ,RANDOMIZED controlled trials ,REPEATED measures design ,OXYGEN consumption ,EXERCISE intensity ,DATA analysis software ,DESCRIPTIVE statistics - Abstract
Purpose: To examine the effects of a whole-body cryotherapy (WBC) protocol (3 min at -110°C) on acute recovery and key variables of endurance performance during high-intensity intermittent exercise in a thermoneutral environment. Methods: Eleven endurance athletes were tested twice in a randomized crossover design in which 5x5 min of high-intensity running (HIR) were followed by I h of passive rest at ~22°C, including either 3 min of whole-hody exposure to -110°C (WBC) or a placebo intervention of 3 min walking (PBO). A ramp-test protocol was performed before HIR (R1) and after the 1-h recovery period (R2). Time to exhaustion (t
lim ) was measured along with alterations in oxygen content of the vastus lateralis (TSI), oxygen consumption (VO2 ), capillary blood lactate, heart rate (HR), and rating of perceived exertion (RPE) during submaximal and maximal running. Results: The difference in tlim between R1 and R2 was lower in WBC than in PBO (P< .05, effect size d = 1.13). During R2, TSI was higher in WBC during submaximal and maximal running (P < .01, d= 0.68-1.01). In addition. VO2 , HR, and RPE were lower at submaximal level of R2 after WBC than in PBO (P = .04 to <.01, d= 0.23-0.83). Conclusion: WBC improves acute recovery during high-intensity intermittent exercise in thermoneutral conditions. The improvements might be induced by enhanced oxygenation of the working muscles, as well as a reduction in cardiovascular strain and increased work economy at submaximal intensities. [ABSTRACT FROM AUTHOR]- Published
- 2015
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17. Physiological Characteristics of Well-Trained Junior Sprint Kayak Athletes.
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Oliveira Borges, Thiago, Dascombe, Ben, Bullock, Nicola, and Coutts, Aaron J.
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LATISSIMUS dorsi physiology ,ACTIVE oxygen in the body ,ANTHROPOMETRY ,ATHLETIC ability ,BIOMECHANICS ,CARDIOPULMONARY system ,CONFIDENCE intervals ,STATISTICAL correlation ,ENERGY metabolism ,EXERCISE physiology ,EXERCISE tests ,HEART beat ,HEMOGLOBINS ,LACTATES ,MATHEMATICS ,NEAR infrared spectroscopy ,PHYSICAL fitness ,PROBABILITY theory ,RESEARCH funding ,ROWING ,SKINFOLD thickness ,MULTIPLE regression analysis ,EFFECT sizes (Statistics) ,ANAEROBIC threshold ,OXYGEN consumption ,ERGOMETRY ,DATA analysis software ,DESCRIPTIVE statistics ,ONE-way analysis of variance - Abstract
This study aimed to profile the physiological characteristics of junior sprint kayak athletes (n = 21, VO2max 4.1 ± 0.7 L/min, training experience 2.7 ± 1.2 y) and to establish the relationship between physiological variables (VO
2max , VO2 kinetics, muscleoxygen kinetics, paddling efficiency) and sprint kayak performance. VO2max , power at VO2max , power:weight ratio, paddling efficiency, VO2 at lactate threshold, and whole-body and muscle oxygen kinetics were determined on a kayak ergometer in the laboratory. Separately, on-water time trials (TT) were completed over 200 m and 1000 m. Large to nearly perfect (-.5 to -.9) inverse relationships were found between the physiological variables and on-water TT performance across both distances. Paddling efficiency and lactate threshold shared moderate to very large correlations (-.4 to -.7) with 200- and 1000-m performance. In addition, trivial to large correlations (-.11 to -.5) were observed between muscle-oxygenation parameters, muscle and whole-body oxygen kinetics, and performance. Multiple regression showed that 88% of the unadjusted variance for the 200-m TT performance was explained by VO2max , peripheral muscle deoxygenation, and maximal aerobic power (P < .001), whereas 85% of the unadjusted variance in 1000-m TT performance was explained by VO2max and deoxyhemoglobin (P < .001). The current findings show that well-trained junior sprint kayak athletes possess a high level of relative aerobic fitness and highlight the importance of the peripheral muscle metabolism for sprint kayak performance, particularly in 200-m races, where finalists and nonfinalists are separated by very small margins. Such data highlight the relative aerobic-fitness variables that can be used as benchmarks for talent-identification programs or monitoring longitudinal athlete development. However, such approaches need further investigation. [ABSTRACT FROM AUTHOR]- Published
- 2015
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18. Effect of Whole-Body Vibration Therapy on Performance Recovery.
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Manimmanakorn, Nuttaset, Ross, Jenny J., Manimmanakorn, Apiwan, Lucas, Samuel J. E., and Hamlin, Michael J.
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EXERCISE ,QUADRICEPS muscle physiology ,ACTIVE oxygen in the body ,ATHLETIC ability ,BIOPHYSICS ,CLINICAL trials ,CONFIDENCE intervals ,CROSSOVER trials ,CYCLING ,EXERCISE physiology ,HEMODYNAMICS ,JUMPING ,LACTATES ,MUSCLE strength ,MYALGIA ,NEAR infrared spectroscopy ,STATISTICAL sampling ,SCIENTIFIC apparatus & instruments ,STRETCH (Physiology) ,VIBRATION (Mechanics) ,EFFECT sizes (Statistics) ,PAIN measurement ,COOLDOWN ,RANDOMIZED controlled trials ,PRE-tests & post-tests ,ERGOMETRY ,EXERCISE intensity - Abstract
Purpose: To compare whole-body vibration (WBV) with traditional recovery protocols after a high-intensity training bout. Methods: In a randomized crossover study, 16 athletes performed 6 × 30-s Wingate sprints before completing either an active recovery (10 min of cycling and stretching) or WBV for 10 min in a series of exercises on a vibration platform. Muscle hemodynamics (assessed via near-infrared spectroscopy) were measured before and during exercise and into the 10-min recovery period. Blood lactate concentration, vertical jump, quadriceps strength, flexibility, rating of perceived exertion (RPE), muscle soreness, and performance during a single 30-s Wingate test were assessed at baseline and 30 and 60 min postexercise. A subset of participants (n = 6) completed a 3rd identical trial (1 wk later) using a passive 10-min recovery period (sitting). Results: There were no clear effects between the recovery protocols for blood lactate concentration, quadriceps strength, jump height, flexibility, RPE, muscle soreness, or single Wingate performance across all measured recovery time points. However, the WBV recovery protocol substantially increased the tissue-oxygenation index compared with the active (11.2% ± 2.4% [mean ± 95% CI], effect size [ES] = 3.1, and –7.3% ± 4.1%, ES = –2.1 for the 10 min postexercise and postrecovery, respectively) and passive recovery conditions (4.1% ± 2.2%, ES = 1.3, 10 min postexercise only). Conclusion: Although WBV during recovery increased muscle oxygenation, it had little effect in improving subsequent performance compared with a normal active recovery. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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19. The Efficacy of a Self-Paced VO2max Test During Motorized Treadmill Exercise.
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Faulkner, James, Mauger, Alexis R., Woolley, Brandon, and Lambrick, Danielle
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MEDICAL protocols ,ACTIVE oxygen in the body ,AEROBIC exercises ,CARDIOPULMONARY system ,EXERCISE ,EXERCISE tests ,LACTATES ,QUESTIONNAIRES ,RESEARCH funding ,T-test (Statistics) ,CROSS-sectional method ,DATA analysis software ,DESCRIPTIVE statistics - Abstract
Purpose: To assess the utility of a self-paced maximal oxygen uptake (VO
2max ) test (SPV) in eliciting an accurate measure of VO2max in comparison with a traditional graded exercise test (GXT) during motorized treadmill exercise. Design: This was a cross-sectional experimental study whereby recreationally trained men (n = 13, 25.5 ± 4.6 y) completed 2 maximal exercise tests (SPV, GXT) separated by a 72-h recovery period. Methods: The GXT was continuous and incremental, with prescribed 1-km/h increases every 2 min until the attainment of VO2max . The SPV consisted of 5 × 2-min stages of incremental exercise, which were self-selected and adjusted according to 5 prescribed RPE levels (RPE 11, 13, 15, 17, and 20). Results: Although no significant differences in VO2max were observed between the SPV and GXT (63.9 ± 3.3 cf 60.9 ± 4.6 mL · kg–1 · min–1 , respectively, P > .05), the apparent 4.7% mean difference may be practically important. The 95% limits-of-agreement analysis was 3.03 ± 11.49 mL · kg–1 · min–1 . Therefore, in the worst-case scenario, the GXT may underestimate measured VO2max as ascertained by the SPV by up to 19%. Conversely, the SPV could underestimate the GXT by 14%. Conclusions: The current study has shown that the SPV is an accurate measure of VO2max during exercise on a motorized treadmill and may provide a slightly higher VO2max value than that obtained from a traditional GXT. The higher VO2max during the SPV may be important when prescribing training or monitoring athlete progression. [ABSTRACT FROM AUTHOR]- Published
- 2015
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20. Cross-Country Skiing and Postexercise Heart-Rate Recovery.
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Mourot, Laurent, Fabre, Nicolas, Andersson, Erik, Willis, Sarah, Buchheit, Martin, and Holmberg, Hans-Christer
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ACADEMIC medical centers ,ACTIVE oxygen in the body ,CONFIDENCE intervals ,CONVALESCENCE ,HEART beat ,LACTATES ,SKIING ,MEDICAL protocols ,REGRESSION analysis ,RESEARCH funding - Abstract
Postexercise heart-rate (HR) recovery (HRR) indices have been associated with running and cycling endurance-exercise performance. The current study was designed (1) to test whether such a relationship also exists in the case of cross-country skiing (XCS) and (2) to determine whether the magnitude of any such relationship is related to the intensity of exercise before obtaining HRR indices. Ten elite male cross-country skiers (mean ± SD; 28.2 ± 5.4 y, 181 ± 8 cm, 77.9 ± 9.4 kg, 69.5 ± 4.3 mL · min
–1 · kg–1 maximal oxygen uptake [VO2max ]) performed 2 sessions of roller-skiing on a treadmill: a 2 × 3-km time trial and the same 6-km at an imposed submaximal speed followed by a final 800-m time trial. VO2 and HR were monitored continuously, while HRR and blood lactate (BLa) were assessed during 2 min immediately after each 6-km and the 800-m time trial. The 6-km time-trial time was largely negatively correlated with VO2max and BLa. On the contrary, there was no clear correlation between the 800-m time-trial time and VO2 , HR, or BLa. In addition, in no case was any clear correlation between any of the HRR indices and performance time or VO2max observed. These findings confirm that XCS performance is largely correlated with VO2max and the ability to tolerate high levels of BLa; however, postexercise HRR showed no clear association with performance. The homogeneity of the group of athletes involved and the contribution of the arms and upper body to the exercise preceding determination of HRR may explain this absence of a relationship. [ABSTRACT FROM AUTHOR]- Published
- 2015
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21. Differences in Oxygenation Kinetics Between the Dominant and Nondominant Flexor Digitorum Profundus in Rock Climbers.
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Giles, David, España Romero, Vanesa, Garrido, Inmaculada, de la O. Puerta, Alejandro, Stone, Keeron, and Fryer, Simon
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ACTIVE oxygen in the body ,ANALYSIS of variance ,CAPILLARIES ,CONFIDENCE intervals ,DYNAMICS ,FOREARM ,HAND ,ISCHEMIA ,MUSCLE contraction ,NEAR infrared spectroscopy ,REPERFUSION ,ROCK climbing ,STATISTICS ,TENDONS ,FINGER physiology ,DATA analysis ,COOLDOWN ,DATA analysis software ,SKELETAL muscle ,DESCRIPTIVE statistics - Abstract
Purpose: To examine differences in oxygenation kinetics in the nondominant and dominant flexor digitorum profundus (FDP) of rock climbers. Methods: Participants were 28 sport climbers with a range of on-site abilities (6a+ to 8a French Sport). Using near-infrared spectroscopy, oxygenation kinetics of the FDP was assessed by calculating the time to half recovery (t
1/2 recovery ) of the tissue-saturation index (TSI) after 3-5 min of ischemia. Results: A 2-way mixed-model ANOVA found a nonsignificant interaction (P = .112) for TSI by sex. However, there was a significant main effect (P = .027) of handedness (dominant vs nondominant FDP). The dominant forearm recovered 13.6% faster (t1/2 recovery mean difference = 1.12 s, 95% CI 0.13-2.10 s) than the nondominant FDP. This was not affected by 6-mo on-site climbing ability or sex (P = .839, P = .683). Conclusions: Significant intraindividual differences in oxygenation kinetics of the FDP were found. Improvements in oxygenation kinetics in the FDP are likely due to the abilities of the muscle to deliver, perfuse, and consume oxygen. These enhancements may be due to structural adaptations in the microvasculature, such as an increase in capillary density and enhanced improvement in capillary filtration. [ABSTRACT FROM AUTHOR]- Published
- 2017
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22. Effect of Different Simulated Altitudes on Repeat-Sprint Performance in Team-Sport Athletes.
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Goods, Paul S. R., Dawson, Brian T., Landers, Grant J., Gore, Christopher J., and Peeling, Peter
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ACTIVE oxygen in the body ,ALTITUDES ,ANALYSIS of variance ,HYPOXEMIA ,ATHLETIC ability ,COMPARATIVE studies ,EXERCISE ,HEART beat ,HYDROGEN-ion concentration ,LACTATES ,HEALTH outcome assessment ,PROBABILITY theory ,EFFECT sizes (Statistics) ,TREADMILLS ,PHYSICAL training & conditioning ,TEAM sports ,REPEATED measures design ,BLIND experiment - Abstract
Purpose: This study aimed to assess the impact of 3 heights of simulated altitude exposure on repeat-sprint performance in team-sport athletes. Methods: Ten trained male team-sport athletes completed 3 sets of repeated sprints (9 x 4 s) on a nonmotorized treadmill at sea level and at simulated altitudes of 2000, 3000, and 4000 m. Participants completed 4 trials in a random order over 4 wk, with mean power output (MPO), peak power output (PPO), blood lactate concentration (Bla), and oxygen saturation (S
2 O2 ) recorded after each set Results: Each increase in simulated altitude corresponded with a significant decrease in S2 O2 . Total work across all sets was highest at sea level and correspondingly lower at each successive altitude (P < .05; sea level < 2000 m < 3000 m < 4000 m). In the first set, MPO was reduced only at 4000 m, but for subsequent sets, decreases in MPO were observed at all altitudes (P < .05; 2000 m < 3000 m < 4000 m). PPO was maintained in all sets except for set 3 at 4000 m (P < .05; vs sea level and 2000 m). BLa levels were highest at 4000 m and significantly greater (P < .05) than at sea level after all sets. Conclusions: These results suggest that “higher may not be better,” as a simulated altitude of 4000 m may potentially blunt absolute training quality. Therefore, it is recommended that a moderate simulated altitude (2000-3000 m) be employed when implementing intermittent hypoxic repeat-sprint training for team-sport athletes. [ABSTRACT FROM AUTHOR]- Published
- 2014
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23. Effects of Domestic Air Travel on Technical and Tactical Performance and Recovery in Soccer.
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Fowler, Peter, Duffield, Rob, and Vaile, Joanna
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SLEEP ,ACTIVE oxygen in the body ,AIR travel ,ANALYSIS of variance ,ANTHROPOMETRY ,ATHLETIC ability ,CLINICAL trials ,CONFIDENCE intervals ,CROSSOVER trials ,EXERCISE physiology ,FATIGUE (Physiology) ,SPECIFIC gravity ,QUESTIONNAIRES ,RESEARCH funding ,SOCCER ,SPORTS sciences ,STATISTICS ,WATER-electrolyte balance (Physiology) ,DATA analysis ,EFFECT sizes (Statistics) ,SPORTS events ,COOLDOWN ,REPEATED measures design ,EXERCISE intensity ,DATA analysis software ,DESCRIPTIVE statistics - Abstract
The current study examined the effects of short-haul air travel on competition performance and subsequent recovery. Six male professional Australian football (soccer) players were recruited to participate in the study. Data were collected from 12 matches, which included 6 home and away matches against the same 4 teams. Together with the outcome of each match, data were obtained for team technical and tactical performance indicators and individual player-movement patterns. Furthermore, sleep quantity and quality, hydration, and perceptual fatigue were measured 2 days before, the day of, and 2 days after each match. More competition points were accumulated (P > .05, d = 1.10) and fewer goals were conceded (P > .05, d = 0.93) in home than in away matches. Furthermore, more shots on goal (P > .05, d = 1.17) and corners (P > .05, d = 1.45) and fewer opposition shots on goal (P > .05, d = 1.18) and corners (P < .05, d = 2.32) occurred, alongside reduced total distance covered (P > .05, d = 1.19) and low-intensity activity (P < .05, d = 2.25) during home than during away matches. However, while oxygen saturation was significantly lower during than before and after outbound and return travel (P < .01), equivocal differences in sleep quantity and quality, hydration, and perceptual fatigue were observed before and after competition away compared with home. These results suggest that, compared with short-haul air travel, factors including situational variables, territoriality, tactics, and athlete psychological state are more important in determining match outcome. Furthermore, despite the potential for disrupted recovery patterns, return travel did not impede player recovery or perceived readiness to train. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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24. Critical Evaluation of Oxygen-Uptake Assessment in Swimming.
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Sousa, Ana, Figueiredo, Pedro, Pendergast, David, Kjendlie, Per-Ludvik, Vilas-Boas, JoÆo P., and Fernandes, Ricardo J.
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SKELETAL muscle physiology ,ACTIVE oxygen in the body ,BIOPHYSICS ,BIOTELEMETRY ,ENERGY metabolism ,EXERCISE physiology ,MEDLINE ,ONLINE information services ,RESEARCH funding ,SPORTS sciences ,SWIMMING ,TIME ,SYSTEMATIC reviews ,EVIDENCE-based medicine ,PROFESSIONAL practice ,PRODUCT design ,PHYSICAL training & conditioning ,OXYGEN consumption ,EXERCISE intensity - Abstract
Swimming has become an important area of sport science research since the 1970s, with the bioenergetic factors assuming a fundamental performance-influencing role. The purpose of this study was to conduct a critical evaluation of the literature concerning oxygen-uptake (VO
2 ) assessment in swimming, by describing the equipment and methods used and emphasizing the recent works conducted in ecological conditions. Particularly in swimming, due to the inherent technical constraints imposed by swimming in a water environment, assessment of VO2max was not accomplished until the 1960s. Later, the development of automated portable measurement devices allowed VO2max to be assessed more easily, even in ecological swimming conditions, but few studies have been conducted in swimming-pool conditions with portable breath-by-breath telemetric systems. An inverse relationship exists between the velocity corresponding to VO2max and the time a swimmer can sustain it at this velocity. The energy cost of swimming varies according to its association with velocity variability. As, in the end, the supply of oxygen (whose limitation may be due to central-O2 delivery and transportation to the working muscles--or peripheral factors--O2 diffusion and utilization in the muscles) is one of the critical factors that determine swimming performance, VO2 kinetics and its maximal values are critical in understanding swimmers' behavior in competition and to develop efficient training programs. [ABSTRACT FROM AUTHOR]- Published
- 2014
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25. Cardiorespiratory and Muscular Responses to Simulated Upwind Sailing Exercise in Optimist Sailors.
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Callewaert, Margot, Boone, Jan, Celie, Bert, De Clercq, Dirk, and Bourgois, Jan G.
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SKELETAL muscle physiology ,ACTIVE oxygen in the body ,ANALYSIS of variance ,AQUATIC exercises ,BLOOD pressure ,CARDIOPULMONARY system ,ELECTROMYOGRAPHY ,EXERCISE ,EXERCISE physiology ,EXERCISE tests ,HEART beat ,HEMOGLOBINS ,LONGITUDINAL method ,MYOGLOBIN ,NEAR infrared spectroscopy ,PULMONARY gas exchange ,RESEARCH funding ,SKINFOLD thickness ,STATISTICS ,T-test (Statistics) ,U-statistics ,DATA analysis ,ELITE athletes ,REPEATED measures design ,OXYGEN consumption ,ERGOMETRY ,EXERCISE intensity ,DATA analysis software - Abstract
The aim of this work was to gain more insight into the cardiorespiratory and muscular (m. vastus lateralis) responses to simulated upwind sailing exercise in 10 high-level male and female Optimist sailors (10.8-14.4 years old). Hiking strap load (HSL) and cardiorespiratory variables were measured while exercising on a specially developed Optimist sailing ergometer. Electromyography (EMG) was used to determine mean power frequency (MPF) and root mean square (RMS). Near-infrared spectroscopy was used to measure deoxygenated Hemoglobin and Myoglobin concentration (deoxy[Hb+Mb]) and re-oxygenation. Results indicated that HSL and integrated EMG of the vastus lateralis muscle changed in accordance with the hiking intensity. Cardiorespiratory response demonstrated an initial significant increase and subsequently steady state in oxygen uptake (VO
2 ), ventilation (VE ), and heart rate (HR) up to circa 40% VO2peak , 30% VE peak and 70% HRpeak respectively. At muscle level, results showed that highly trained Optimist sailors manage to stabilize the muscular demand and fatigue development during upwind sailing (after an initial increase). However, approaching the end of the hiking exercise, the MPF decrease, RMS increase, and deoxy[Hb+Mb] increase possibly indicate the onset of muscle fatigue. [ABSTRACT FROM AUTHOR]- Published
- 2014
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26. Muscle Oxygenation Asymmetry in Ice Speed Skaters: Not Compensated by Compression.
- Author
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Born, Dennis-Peter, Zinner, Christoph, Herlitz, Britta, Richter, Katharina, Holmberg, Hans-Christer, and Sperlich, Billy
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EXERCISE ,BODY composition ,QUADRICEPS muscle physiology ,ACTIVE oxygen in the body ,ANALYSIS of variance ,ANTHROPOMETRY ,COMPRESSION stockings ,ATHLETIC ability ,CLINICAL trials ,CROSSOVER trials ,EXERCISE physiology ,HEART rate monitoring ,LACTATES ,NEAR infrared spectroscopy ,STATISTICAL sampling ,ICE skating ,SPORTS sciences ,STATISTICS ,T-test (Statistics) ,DATA analysis ,QUADRICEPS muscle ,EFFECT sizes (Statistics) ,BODY mass index ,RANDOMIZED controlled trials ,PRE-tests & post-tests ,ELITE athletes ,REPEATED measures design ,OXYGEN consumption ,DATA analysis software ,DESCRIPTIVE statistics - Abstract
Purpose: The current investigation assessed tissue oxygenation and local blood volume in both vastus lateralis muscles during 3000-m race simulations in elite speed skaters on ice and the effects of leg compression on physiological, perceptual, and performance measures. Methods: Ten (6 female) elite ice speed skaters completed 2 on-ice trials with and without leg compression. Tissue oxygénation and local blood volume in both vastus lateralis muscles were assessed with near-infrared spectroscopy. Continuous measures of oxygen uptake, ventilation, heart rate, and velocity were conducted throughout the race simulations, as well as blood lactate concentration and ratings of perceived exertion before and after the trials. In addition, lap times were assessed. Results: The investigation of tissue oxygénation in both vastus lateralis muscles revealed an asymmetry (P < .00; effect size = 1.81) throughout the 3000-m race simulation. The application of leg compression did not affect oxygénation asymmetry (smallest P = .99; largest effect size = 0.31) or local blood volume (P = .33; 0.95). Lap times (P = .88; 0.43), velocity (P = .24; 0.84), oxygen uptake (P = .79; 0.10), ventilation (P = . 11 ; 0.59), heart rate (P = .21 ; 0.89), blood lactate concentration (P = .82; 0.59), and ratings of perceived exertion (P = .19; 1.01) were also unaffected by the different types of clothing. Conclusion: Elite ice speed skaters show an asymmetry in tissue oxygénation of both vastus lateralis muscles during 3000-m events remaining during the long gliding phases along the straight sections of the track. Based on the data, the authors conclude that there are no performance-enhancing benefits from wearing leg compression under a normal racing suit. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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27. Does Upper-Body Compression Improve 3 x 3-Min Double-Poling Sprint Performance?
- Author
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Sperlich, Billy, Born, Dennis-Peter, Zinner, Christoph, Hauser, Anna, and Holmberg, Hans-Christer
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EXERCISE ,ACTIVE oxygen in the body ,ANALYSIS of variance ,COMPRESSION stockings ,ATHLETIC ability ,BODY composition ,CARDIAC output ,COMPARATIVE studies ,CROSS-country skiing ,CROSSOVER trials ,EXERCISE physiology ,EXERCISE tests ,HEART rate monitoring ,HEMOGLOBINS ,BIOELECTRIC impedance ,LACTATES ,NEAR infrared spectroscopy ,PULMONARY gas exchange ,RESEARCH funding ,SPORTS sciences ,EFFECT sizes (Statistics) ,REPEATED measures design ,OXYGEN consumption ,ERGOMETRY ,EXERCISE intensity ,DATA analysis software ,DESCRIPTIVE statistics ,STROKE volume (Cardiac output) - Abstract
Purpose: To evaluate whether upper-body compression affects power output and selected metabolic, cardio- respiratory, hemodynamic, and perceptual responses during three 3-min sessions of double-poling (DP) sprint. Method: Ten well-trained male athletes (25 ± 4 y, 180 ± 4 cm, 74.6 ± 3.2 kg) performed such sprints on a DP ski ergometer with and without a long-sleeved compression garment. Result: Mean power output was not affected by such compression (216 ± 25 W in both cases; P = 1.00, effect size [ES] = 0.00), although blood lactate concentration was lowered (P < .05, ES = 0.50-1.02). Blood gases (ES = 0.07-0.50), oxygen uptake (ES = 0.04-0.28), production of carbon dioxide (ES = 0.01-0.46), heart rate (ES = 0.00-0.21), stroke volume (ES = 0.33-0.81), and cardiac output (ES = 0.20-0.91) were also all unaffected by upper-body compression (best P = 1.00). This was also the case for changes in the tissue saturation index (ES = 0.45-1.17) and total blood content of hemoglobin (ES = 0.09-0.85), as well as ratings of perceived exertion (ES = 0.15-0.88; best P = .96). Conclusion: The authors conclude that the performance of well-trained athletes during 3 x 3-min DP sprints will not be enhanced by upper-body compression. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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28. Molecular detection and characterisation of biologically relevant free radicals during surgical ischaemia-reperfusion
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Gutowski, Mariusz, Bailey, Damian, George, William, and Ford, William
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541.244 ,Active oxygen in the body ,Active oxygen Pathophysiology ,Active oxygen Physiological effect - Abstract
Oxygen is one of the most important molecules in human beings. Our research is focused on how the human body can respond and adapt to the physiological challenge posed by a lack of oxygen. Ascorbic acid (Vitamin C) is one of the most important and considered the most effective water-soluble, chain-breaking antioxidant in human plasma, with the capacity to prevents damage by free radicals. This thesis presents four studies investigating the phenomenon of Reactive Oxygen Species (ROS) generation in the many different surgical conditions in the animal and in the human. Study one investigated the geometry and thermodynamic properties of vitamin C. Calculations were carried out at the restricted and unrestricted B3LYP/6-31+G(d,p), B3LYP/6-311++G(d,p) and B3LYP/EPR-II levels for two conformers (1 and 2) of L-ascorbic acid and their respective oxidation products to monodehydroascorbates of ab-initio methods by Gaussian O3W package. Conformer 1, free radical properties are compared with previously published calculations in the gaseous and aqueous solution states and with experimental EPR values. Calculated molecular structures, EPR (electron paramagnetic resonance spectroscopy), the vibration spectral and energetic properties and all are reported including some proposed changes to previous EPR assignments. Conformer 2 of L-ascorbic acid is predicted to have lower energy than Conformer 1, under the method and basis sets used, by between 11 and 26 kJ mol-1 and is stabilised by internal hydrogen bonding. Relaxed potential energy surface (PES) scans were carried out for two proton transfer processes and relative energies of stable minima and barriers between them determined. Hydrogen transfer is predicted in two systems with favourable spatial arrangements of O–H and O groups for which relaxed potential energy surface scans are reported. Calculated vibrational wavenumber values are provided for selected C=C, C=O, C–H and O–H modes assigned to particular groups and significant calculated EPR hyperfine coupling constants (HCC) values for splitting by H(1) and C(13) for radical species are also reported. These calculations contribute to a better understanding of the complex role of L-ascorbic acid and its various oxidised, neutral, ionic and radical forms in biochemistry and medicine. Study two examined if vitamin C could ameliorate the damaging effects of I-R on myocardium and we postulated that the mechanism of vitamin C protection against iii I-R-induced cell death involved quenching of ROS. In the vitamin C group after 5 min of reperfusion a significant, sudden increase of diastolic pressure in the heart was noted and reached a maximum of 77 mmHg after 12 min of reperfusion and then gradually decreased to 51 mmHg after 60 min of reperfusion period but was quicker than in Control group reaching 37 mmHg by the end of the reperfusion period. The level of A·− (ascorbate free radicals) sudden and massive increased at the time of reperfusion in the Vitamin C group. This increase was associated with poor mechanical function in hearts as indicated by the significantly depressed recovery process. After 30 min of global, now-flow ischaemia and 60min of reperfusion infarct size averaged 33% ± 1 in Control group and 30 % ± 1 in Vitamin C group, respectively, (P<0.05). There is strong evidence that oxygen centered radicals contribute to postischaemic dysfunction after global ischaemia. Our data unquestionably suggest that the large production of A·− was associated with a greater depression in myocardial contractile function, therefore could represent a marker of oxidative stress during I-R and could be related to the functional impairment during reperfusion. In summary, we have used the animal models of isolated heart perfusion to provide evidence that vitamin C did not reduce the infarct size, however “tendency” towards a decrease (↓) in infarct size with ascorbate and it protects from oxidative damage during global I-R as manifested by decreased concentrations of A·− and enhance recovery of mechanical function such as diastolic pressure and LVDP in postischaemic working rat hearts. Study three was designed to test the hypothesis that the physiological trauma associated with venous cannulation may artefactually stimulate systemic free radical formation in the acute phase that if not accounted for may under-estimate the oxidative stress response to exercise. The relationship between the time of venepuncture and the level of free radical generation during normoxic conditions was further investigated. The venous cannulation in Phase I, increased plasma A·− by 347 ± 173 AU/√G, P <0.05 after 2min of venepuncture with further increases observed after 5min and 10min of venous cannulation, respectively (403 ± 178 AU/√G; 462 ± 93 AU/√G, P < 0.05) vs baseline point time. After this time the level of A·− slightly blunted as to achieve a similar level to baseline point control after 30 minutes. In phase II the exerciseinduced increase in A·− was subsequently shown to be 48% greater (30min as opposed to the 2min post-cannulation resting baseline)(1754 ± 361 vs. 1979 ± 375 AU, P <0.05). Our findings demonstrate and confirm that venous cannulation per se stimulates iv the systemic formation of free radicals as an acute phase response which peaks at 10min and require approximately 15min to normalise. This has important interpretive implications for future studies that employ catheterisation. The final Study examined if the combination of exercise and inspiratory hypoxia would further compound regional tissue de-oxygenation that is frequently encountered during the ischaemic phase of surgery and thus, by consequence increase oxidative stress. The aim of the study was to further understand a potential relationship between oxidative stress and alterations in muscle oxygenation. Clear significant increases in the plasma concentration of A·− were detected in the peripheral blood of patients (normoxia(baseline) vs 6 data points of reperfusion after 5min of global ischaemic condition, P<0.05),(baseline vs immediate after ischaemia; 2337±525 vs 2633±508, AU, respectively). During global ischaemia the regional muscle oxygenation significantly decreased (↓∆O2Hb-oxyhaemoglobin), ↑∆HHb- deoxyhaemoglobin ), although increased regional blood volume (↑∆tHb- total haemoglobin). From the end of global ischaemia to 10 min after the regional muscle oxygenation progressively back to the start data point (↓∆HHb, ↑∆O2Hb). This study demonstrates for the first time that the I-R has got a big influence on the muscle oxygenation to increased ROS and the return of values towards baseline period in reperfusion stage appears to coincide with increased oxidative stress. Moreover, the present study has also demonstrated increased A·− level as early as the ischaemic phase of experiment independent of perioperative changes in the partial pressure of oxygen (pO2), elucidate a potentially important role for oxidative stress in provoking an appropriate vasodilation (NO-bioavailability) during the I-R period. This work demonstrates that; - Ascorbate is an antioxidant that can scavenge tissue and blood borne free radical, is essential in controlled amounts and is capable of initiating protective adaptation in the face of oxidative stress for the maintenance of physiological homeostasis. - Reperfusion is always associated with a sudden and massive release of ascorbate free radicals, with a maximal liberation within the first minutes of reperfusion. Vitamin C tended to reduce infarct size and protects from oxidative damage during global ischaemia and reperfusion. - The venous cannulation alone is enough per se stimulates the systemic formation of free radicals as a acute phase response. If this baseline artefact is not taken into account, the true magnitude of the exercise-induced oxidative stress response will be under-estimated., The I-R has got a major influence on the muscle oxygenation to increased ROS and the return of values towards baseline period in reperfusion stage appears to coincide with increased oxidative stress. Using the state-of-the-art molecular techniques that include Electron Paramagnetic Spectroscopy (EPR) for the direct detection of free radicals and Near Infrared Spectroscopy (NIRS) for the direct detection of muscle oxygenation these studies have attempted to translate the basic mechanisms associated with free radical formation during I-R and have provided unique insight into the basic mechanisms responsible for the oxidative stress with the ultimate objective of developing novel antioxidant interventions that can provide effective prophylaxis.
- Published
- 2011
29. The Reliability of a Rugby League Movement-Simulation Protocol Designed to Replicate the Performance of Interchanged Players.
- Author
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Waldron, Mark, Highton, Jamie, and Twist, Craig
- Subjects
ACTIVE oxygen in the body ,CLINICAL trials ,COMPUTER simulation ,CONFIDENCE intervals ,EXERCISE ,GEOGRAPHIC information systems ,RUGBY football ,T-test (Statistics) ,BODY movement ,RESEARCH methodology evaluation ,DATA analysis software ,DESCRIPTIVE statistics - Abstract
Purpose: This study assessed the reliability of a rugby league movement-simulation protocol, relative to interchanged players (RLMSP-i). Methods: Fifteen male participants completed 2 trials of the RLMSP-i, separated by 1 wk. The RLMSP-i comprised low- to moderate-intensity running, interspersed by high-intensity sprinting and tackling activity, based on global positioning system (GPS) data recorded during Super League performances. Results: The lowest coefficient of variation (CV ± 95% CI) was observed for total m/min during both interchange bout 1 (1.1% ± 0.2%) and bout 2 (1.0% ± 0.2%). The percentage of heart rate peak and ratings of perceived exertion demonstrated CVs of 1.2-2.0% and 2.9-3.5%, respectively. The poorest agreement between trials was found for blood lactate concentration (16.2% ± 2.8%). In no case was the CV smaller than the smallest worthwhile change, yet in every case the moderate changes were larger than the CV. Conclusions: The RLMSP-i's reliability is sufficient to enable the detection of moderate changes in various performance and physiological measurements that accurately simulate some, but not all, aspects of rugby league matches. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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30. Rapidity of Response to Hypoxic Conditions During Exercise.
- Author
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Henslin Harris, Kayla B., Foster, Carl, De Koning, Jos J., Dodge, Christopher, Wright, Glenn A., and Porcari, John P.
- Subjects
EXERCISE ,ACTIVE oxygen in the body ,ALTITUDES ,ANALYSIS of variance ,HYPOXEMIA ,ANTHROPOMETRY ,ATHLETES ,ATHLETIC ability ,CARDIOPULMONARY system ,CLINICAL trials ,CYCLING ,EXERCISE physiology ,EXERCISE tests ,RESEARCH funding ,STATISTICAL sampling ,STATISTICS ,TIME ,DATA analysis ,RANDOMIZED controlled trials ,REPEATED measures design ,ERGOMETRY ,BLIND experiment ,EXERCISE intensity ,DESCRIPTIVE statistics - Abstract
Previous studies have found decreases in arterial oxygen saturation to be temporally linked to reductions in power output (PO) during time-trial (TT) exercise. The purpose of this study was to determine whether preexercise desaturation (estimated from pulse oximetry [S
P O2 ]), via normobaric hypoxia, would change the pattern of PO during a TT. Purpose: The authors tested the hypothesis that the starting PO of a TT would be reduced in the EARLY trial secondary to a reduced SP O2 but would not be reduced in LATE until ~30 s after the start of the TT. Methods: Eight trained cyclists/triathletes (4 male, 4 female) performed 3 randomly ordered 3-km TTs while breathing either room air (CONTROL) or hypoxic air administered 3 min before the start of the TT (EARLY) or at the beginning of the TT (LATE). Results: There was no effect of hypoxia on PO during the first 0.3 km of either the EARLY or the LATE trial compared with CONTROL, although there was a significant decrease in pre-TT SP O2 in EARLY vs CONTROL and LATE. The time for PO to decrease was ~40 s after the start of the TT in both EARLY and LATE. Conclusions : The results support the strong effect of the preexercise template on the pattern of PO during simulated competition and suggest that reductions in SP O2 are not direct signals to decrease PO. [ABSTRACT FROM AUTHOR]- Published
- 2013
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31. Maximal Oxygen Uptake Validation in Children With Expiratory Flow Limitation.
- Author
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Robben, Katherine E., Poole, David C., and Harms, Craig A.
- Subjects
PHYSICAL fitness ,EXERCISE tests ,ACTIVE oxygen in the body ,ANALYSIS of variance ,CARDIOPULMONARY system ,CONFIDENCE intervals ,HEART beat ,LUNGS ,RESEARCH methodology ,OXIMETRY ,PROBABILITY theory ,PULMONARY gas exchange ,RESPIRATION ,RESPIRATORY measurements ,SEX distribution ,PULSE oximeters ,OXYGEN consumption ,VITAL capacity (Respiration) ,DATA analysis software - Abstract
Copyright of Pediatric Exercise Science is the property of Human Kinetics Publishers, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2013
- Full Text
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32. 辣椒红素的生物利用度、生理功能及 机制研究进展.
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黎智华 and 王 恬
- Subjects
ACTIVE oxygen in the body ,HOT peppers ,FOOD additives ,CELL anatomy ,DNA ,FEED additives ,CAROTENOIDS - Abstract
Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2020
- Full Text
- View/download PDF
33. Physical Fitness and Performances of an Amputee Cycling World Champion: A Case Study.
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Menaspà, Paolo, Rampinini, Ermanno, Tonietti, Lara, and Bosio, Andrea
- Subjects
PHYSICAL fitness ,ACTIVE oxygen in the body ,AMPUTEES ,ATHLETIC ability ,CANCER patients ,CYCLING ,HEART beat ,HEMOGLOBINS ,OSTEOSARCOMA ,ATHLETES with disabilities ,DESCRIPTIVE statistics - Abstract
Purpose: To describe the physical fitness of a top-level lower limb amputee (LLA) cyclist and paracycling time-trial (TT) race demands. Methods: The 40-y-old male unilateral transfemoral amputee TT World Champion was tested in a laboratory for peak oxygen uptake (VO
2peak ). ventilatory threshold (VT2 ), power output (PO), and hemoglobin mass (Hb-mass). Moreover, several measures (eg, PO, heart rate [HR], cadence) were collected during 4 international TT competitions in the same season. The races' intensity was evaluated as time spent below, at, or above VT2. Results: The cyclist (1.73 m, 55.0 kg) had a VO2peak of 3.372 L/min (61.3 mL - kg-1 - min-1 ). The laboratory peak PO was 315 W (5.7 W/kg). The maximal HR was 208 beats/min, and his Hb-mass was 744 g ( 13.5 g/kg). The TTs were meanly 18 ± 4.5 km in length, and the mean PO was 248 ± 8 W with a cadence of 92 ± 1 rpm. During the TTs, the cyclist spent 23% ± 9% of total time at VT2 , 59% ± 10% below, and 18% ± 5% above this intensity. Conclusions: The subject's relative VO2peak is higher than previously published data on LLA, and surprisingly it is even higher than "good" ACSM normative data for nondisabled people. The intensity of the races was found to be similar to cycling TTs of the same duration in elite female cyclists. These results might be useful to devlop specific training schedules and enhance perofjmrance of LLA cyclists. [ABSTRACT FROM AUTHOR]- Published
- 2012
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34. The Tour de France: An Updated Physiological Review.
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Santalla, Alfredo, Earnest, Conrad P., Marroyo, Jos&eeacute; A., and Lucia, Alejandro
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ACTIVE oxygen in the body ,ANTHROPOMETRY ,ATHLETIC ability ,CYCLING ,DOPING in sports ,LACTATES ,SPORTS sciences ,SPORTS events - Abstract
From its initial inception in 1903 as a race premised on a publicity stunt to sell newspapers, the Tour de France had grown and evolved over time to become one of the most difficult and heralded sporting events in the world. Though sporting science and the Tour paralleled each other, it was not until the midlate 1980s, and especially the midlate 1990s (with the use of heart-rate monitors) that the 2 began to unify and grow together. The purpose of this brief review is to summarize what is currently known of the physiological demands of the Tour de France, as well as of the main physiological profile of Tour de France competitors. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
35. Dietary Nitrate Supplementation Improves Rowing Performance in Well-Trained Rowers.
- Author
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Bond, Hannah, Morton, Lillian, and Braakhuis, Andrea J.
- Subjects
- *
THERAPEUTIC use of nitric oxide , *ACTIVE oxygen in the body , *BEETS , *BLOOD pressure , *CONFIDENCE intervals , *CROSSOVER trials , *DIETARY supplements , *HEART beat , *PLACEBOS , *RESEARCH funding , *PLANT roots , *ROWING , *BODY movement , *RANDOMIZED controlled trials , *ERGOMETRY , *BLIND experiment , *FOOD diaries , *DATA analysis software , *THERAPEUTICS - Abstract
Increased plasma nitrate concentrations from dietary sources of nitrate have proven to benefit exercise performance. Beetroot (BR) contains relatively high levels of nitrate (NO3–), which increases nitric oxide stores. This study investigated whether dietary nitrate supplementation, in the form of a BR beverage, would improve rowing performance during ergometer repetitions. In a randomized crossover design, 14 well-trained junior male rowers consumed 500 ml of either BR or placebo (PL) daily for 6 d. After supplementation, rowers completed 6 maximal 500-m ergometer repetitions and times were recorded. A 7-d washout period separated the 2 trials. Blood pressure, oxygen saturation, maximum heart rate, urine (specific gravity, pH, and nitrites), and lactates were collected for analysis at baseline and pre- and postperformance. Changes in the mean with 95%confidence limits were calculated. There was a likely benefit to average repetition time in the BR condition, compared with PL (0.4%, 95% confidence limits, ± 1.0%). In particular, Repetitions 4–6 showed an almost certain benefit in rowing time on BR (1.7%, 95% CL, ± 1.0%). The underlying mechanism for the observed results remains unknown, as differences observed in rowers’ physiological measures between the 2 conditions were unclear. Conclusively, nitrate supplementation in the form of BR juice resulted in improved maximal rowing-ergometer repetitions, particularly in the later stages of exercise. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
36. Seasonal Changes in Fitness Parameters in a World Champion Rowing Crew.
- Author
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Mikulic, Pavle
- Subjects
PHYSICAL fitness ,ACTIVE oxygen in the body ,ANTHROPOMETRY ,BODY composition ,ROWING ,SEASONS ,ELITE athletes ,DESCRIPTIVE statistics - Abstract
Purpose: To examine variations in physical, physiological, and performance parameters over an annual training cycle in a world champion rowing crew. Methods: Four world-class rowers, all of them members of the men's heavyweight quadruple sculls squad who are current world rowing champions, were assessed 3 times at regular 4-mo intervals during the 2011 season (November 2010, March 2011, and July 2011). Physical assessments included stature, body mass, body composition, whereas physiological and performance assessments obtained during an incremental rowing ergometer test to exhaustion included maximum oxygen uptake and anaerobic gas-exchange threshold with corresponding power output values. Results: Body mass (~95 kg) and body composition (~12% body fat) remained stable over the annual training cycle. Power output at anaerobic gas-exchange threshold increased +16% from November to July, whereas the corresponding oxygen uptake, expressed as a percentage of maximum oxygen uptake, increased from 83% to 90%. Maximum oxygen uptake decreased from 6.68 L/min in November to 6.10 L/min in March before rising to 6.51 L/min in July. The corresponding power output increased steadily from 450 W to 481 W. Conclusion: Seasonal variation in body mass and body composition of 4 examined world-class rowers was minimal. Oxygen uptake and power output corresponding to anaerobic threshold continuously increased from off-season to peak competition season. Seasonal variation in maximum oxygen uptake reached ~10%; however, it remained above 6 L/min, that is, the value consistently observed in top caliber heavyweight rowers regardless of the time of the assessment. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
37. Effects of Short-Term Training With Uncoupled Cranks in Trained Cyclists.
- Author
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Burns, Jack M., Peiffer, Jeremiah J., Abbiss, Chris R., Watson, Greig, Burnett, Angus, and Laursen, Paul B.
- Subjects
ACTIVE oxygen in the body ,ANALYSIS of variance ,ATHLETES ,ATHLETIC ability ,ATHLETIC equipment ,CYCLING ,ELECTROMYOGRAPHY ,LEG ,MUSCLE strength testing ,EFFECT sizes (Statistics) ,PHYSICAL training & conditioning ,DATA analysis software ,DESCRIPTIVE statistics - Abstract
Purpose: Manufacturers of uncoupled cycling cranks claim that their use will increase economy of motion and gross efficiency. Purportedly, this occurs by altering the muscle-recruitment patterns contributing to the resistive forces occurring during the recovery phase of the pedal stroke. Uncoupled cranks use an independent-clutch design by which each leg cycles independently of the other (ie, the cranks are not fixed together). However, research examining the efficacy of training with uncoupled cranks is equivocal. The purpose of this study was to determine the effect of short-term training with uncoupled cranks on the performance-related variables economy of motion, gross efficiency, maximal oxygen uptake (VO
2max ), and muscle-activation patterns. Methods: Sixteen trained cyclists were matched-paired into either an uncoupled-crank or a normal-crank training group. Both groups performed 5 wk of training on their assigned cranks. Before and after training, participants completed a graded exercise test using normal cranks. Expired gases were collected to determine economy of motion, gross efficiency, and VO2max , while integrated electromyography (iEMG) was used to examine muscle-activation patterns of the vastus lateralis, biceps femoris, and gastrocnemius. Results: No significant changes between groups were observed for economy of motion, gross efficiency, VO2max , or iEMG in the uncoupled- or normal-crank group. Conclusions: Five weeks of training with uncoupled cycling cranks had no effect on economy of motion, gross efficiency, muscle recruitment, or VO2max compared with training on normal cranks. [ABSTRACT FROM AUTHOR]- Published
- 2012
- Full Text
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38. A Quasi-Experimental Study of Chinese Top-Level Speed Skaters' Training Load: Threshold Versus Polarized Model.
- Author
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Hongjun Yu, Xiaoping Chen, Weimo Zhu, and Chunmei Cao
- Subjects
ACTIVE oxygen in the body ,ANALYSIS of variance ,ATHLETIC ability ,HEART beat ,LACTATES ,RESEARCH methodology ,PHYSICAL fitness ,ICE skating ,STATISTICS ,TIME ,DATA analysis ,SPORTS events ,PHYSICAL training & conditioning ,EXERCISE intensity ,DESCRIPTIVE statistics - Abstract
Purpose: To examine the effectiveness of threshold and polarized models in the training organization of Chinese top-level sprint speed skaters using a 2-y quasi-experimental design. Methods: Two years (2004-05 and 2005-06 seasons) of the Chinese national speed-skating team's daily training load (N = 9; 5 men, 23.6 ± 1.7 y, weight 76.6 ± 4.1 kg, competitive experience 5.0 ± 0.8 y, 500-m time 35.45 ± 0.72 s, 1000-m time 71.18 ± 2.28 s; 4 women, 25.3 ± 6.8 y, 73.0 ± 8.5 kg, 6.3 ± 3.5 y, 37.81 ± 0.46 s, 75.70 ± 0.81 s) were collected and analyzed. Each season's training load included overall duration (calculated in min and km), frequency (calculated by overall sessions), and training intensity (measured by ear blood lactate or estimated by heart rate), Their performances at national, World Cup, and Olympic competitions during the 2 seasons (2004-06), as well as lactate data measured 15 and 30 min after these competitions, were also collected and analyzed. Based on the lactate data (<2, 2-4, >4 mmol/L), training zones were classified as low, moderate, and high intensity. Results: The total durations and frequencies of the training load were similar across the seasons, but a threshold-training model distribution was used in 2004-05, and a polarized-training-load organization in 2005-06. Under the polarized-training model, or load organization, all speed skaters' performance improved and their lactate after competition decreased considerably. Conclusion: Training-intensity distribution based on a polarized-training model led to the success in top Chinese sprint speed skaters in the 2005-06 season. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
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39. Tissue Oxygenation in Men and Women During Repeated-Sprint Exercise.
- Author
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Smith, Kurt J. and Billaut, François
- Subjects
ACTIVE oxygen in the body ,ANALYSIS of variance ,EXERCISE tests ,FATIGUE (Physiology) ,NEAR infrared spectroscopy ,OXIMETRY ,RESEARCH funding ,RUNNING ,SEX distribution ,STATISTICS ,PULSE oximeters ,DATA analysis ,DATA analysis software ,DESCRIPTIVE statistics - Abstract
Purpose: To understand the role of O
2 utilization in the sex differences of fatigue during intermittent activity, we compared the cerebral (prefrontal lobe) and muscle (vastus lateralis) oxygenation of men and women during repeated-sprint exercise (RSE). Methods: Ten men and 10 women matched for initial-sprint mechanical work performed ten, 10 s cycle sprints (with 30 s of rest) under normoxic (NM: 21% FI O2 ) and acute hypoxic (HY: 13% FI O2 ) conditions in a randomized single-blind and crossover design. Mechanical work was calculated and arterial O2 saturation (SpO2 ) was estimated via pulse oximetry during every sprint. Cerebral and muscle oxy- (O2 Hb) and deoxy-hemoglobin (HHb) were monitored continuously by near-infrared spectroscopy. Results: Compared with NM, work decrement was accentuated (P = 0.01) in HY for both men (-16.4 ± 10.3%) and women (-16.8 ± 9.0%). This was associated with lower SpO2 and lower cerebral Δ[O2 Hb] in both sexes (-13.6 ± 7.5%, P = .008, and -134.5 ± 73.8%, P = .003, respectively). These HY-induced changes were nearly identical in these men and women matched for initial-sprint work. Muscle Δ[HHb] increased 9-fold (P = .009) and 5-fold (P = .02) in men and women, respectively, and plateaued. This muscle deoxygenation was not exacerbated in HY. Conclusions: Results indicate that men and women matched for initial-sprint work experience similar levels of fatigue and systemic, cerebral, and peripheral adjustments during RSE performed in NM and HY. These data suggest that cerebral deoxygenation imposes a limitation to repeated-sprint performance. [ABSTRACT FROM AUTHOR]- Published
- 2012
- Full Text
- View/download PDF
40. The Role of Aerobic Fitness on Session Rating of Perceived Exertion in Futsal Players.
- Author
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Milanez, Vinícius F., Pedro, Rafael E., Moreira, Alexandre, Boullosa, Daniel A., Salle-Neto, Fuiad, and Nakamura, FábioY.
- Subjects
TEAM sports ,ACTIVE oxygen in the body ,ANALYSIS of variance ,STATISTICAL correlation ,EXERCISE ,EXERCISE tests ,SENSORY perception ,STATISTICS ,DATA analysis ,PHYSICAL training & conditioning ,DATA analysis software - Abstract
Purpose: The aim of this study was to verify the influence of aerobic fitness (VO
2 max) on internal training loads, as measured by the session rating of perceived exertion (session-RPE) method. Methods: Nine male professional outfield futsal players were monitored for 4 wk of the in-season period with regards to the weekly accumulated session-RPE, while participating in the same training sessions. Single-session-RPE was obtained from the product of a 10-point RPE scale and the duration of exercise. Maximal oxygen consumption was determined during an incremental treadmill test. Results: The average training load throughout the 4 wk period varied between 2,876 and 5,035 arbitrary units. Technical-tactical sessions were the predominant source of loading. There was a significant correlation between V02 max (59.6 ± 2.5 mL • kg-1 • min-1 ) and overall training load accumulated over the total period (r = -0.75). Conclusions: The VO2 max plays a key role in determining the magnitude of an individual's perceived exertion during futsal training sessions. [ABSTRACT FROM AUTHOR]- Published
- 2011
- Full Text
- View/download PDF
41. The Relationship Between Serum and Salivary Cortisol Levels in Response to Different Intensities of Exercise.
- Author
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VanBruggen, Mitch D., Hackney, ,Anthony C., McMurray, Robert G., and Ondrak, Kristin S.
- Subjects
ACTIVE oxygen in the body ,ANALYSIS of variance ,EXERCISE tests ,HEART beat ,HYDROCORTISONE ,IMMUNOENZYME technique ,SALIVA ,STATISTICS ,DATA analysis ,COOLDOWN ,REPEATED measures design ,EXERCISE intensity ,DATA analysis software - Abstract
Purpose: The effect of exercise intensity on the tracking of serum and salivary cortisol responses was examined in 12 endurance-trained males (maximal oxygen uptake [VO
2 max] = 58.2 ± 6.4 mL/kg/min). Methods: Subjects rested for 30 min (control) and exercised on a cycle ergometer for 30 min at 40% (low). 60% (moderate), and 80% (high intensity) of VO2 max on separate days. Serum and saliva samples were collected pretrial, immediately posttrial, and 30 min into the recovery period from each trial. Results: Cortisol responses increased significantly for both serum (40.4%; P = .001 ) and saliva ( 170.6%; P = .007) only in response to high-intensity exercise. Peak saliva cortisol occurred at 30 min of recovery, whereas peak serum was at the immediate posttrial sampling time point. The association between serum and saliva cortisol across all trials was examined using concordance correlation (Rc ) analysis, which accounts for repeated measures. The overall correlation between serum and saliva cortisol levels in all matched samples was significant (Rc = 0.728; P = .001 ). The scatter plot revealed that salivary cortisol responses tracked closely to those of serum at lower concentrations, but not as well at higher concentrations. Conclusions: Findings suggest salivary measurements of cortisol closely mirror those in the serum and that peak salivary concentrations do not occur until at least 30 min into the recovery from intense exercise. [ABSTRACT FROM AUTHOR]- Published
- 2011
- Full Text
- View/download PDF
42. Energy System Contributions to the Special Judo Fitness Test.
- Author
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Frainchini, Emerson, Sterkowicz, Stanislaw, Szmatlan-Gabrys, Urszula, Gabrys, Tomasz, and Garnys, Michal
- Subjects
ACTIVE oxygen in the body ,AEROBIC exercises ,ANALYSIS of variance ,ATHLETIC ability ,EXERCISE tests ,LACTATES ,MARTIAL arts ,STATISTICS ,DATA analysis ,ANAEROBIC exercises ,EXERCISE intensity ,DATA analysis software - Abstract
Purpose: This study investigated the energy system contributions of judo athletes to the Special Judo Fitness Test (SJFT). Methods: Fourteen male judo athletes performed the SJFT, which comprised three periods of judo activity (A = 15 s, B and C = 30 s) interspersed wit h 10 s rest intervals. During this test, one athlete threw two others positioned 6 m from each other using the ippon-seoi-nage technique. The fractions of the aerobic, anaerobic alactic and anaerobic lactic systems were calculated based on oxygen uptake, the fast component of excess postexercise oxygen uptake, and changes in net blood lactate, respectively. The contribution of the three energy systems was compared using a repeated measures analysis of variance and Bonferroni's multiple comparisons test. Compound symmetry, or sphericity, was determined by Mauchly's test. A level of significance of 5% (P< .05) was adopted in all analyses. Results: The alactic energy system presented a higher (F = 20.9; P< .001; power observed = 1.0) contribution (86.8 ± 23.6 kJ; 42.3 ± 5.9%) during the test when compared with both aerobic (57.1 ± 11.3 kJ; 28.2 ± 2.9%) and lactic (58.9 ± 12.1 kJ; 29.5 ± 6.2%) energy systems (P < .001 for both comparisons). Conclusions: The higher alactic contribution seems to be a consequence of the high-intensity efforts performed during the test, and its intermittent nature. Thus, when using the SJFT, coaches are evaluating mainly their athletes' anaerobic alactic system, which can be considered to be the most predominant system contributing to the actions (techniques) performed in the match. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
43. Quantifying Training Intensity Distribution in a Group of Norwegian Professional Soccer Players.
- Author
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Algroy, Erling A., Hetlelid, Ken J., Seiler, Stephen, and Pedersen, Jørg I. Stray
- Subjects
ACTIVE oxygen in the body ,ANALYSIS of variance ,COMPUTER software ,EXERCISE tests ,FATIGUE (Physiology) ,HEART beat ,MUSCLES ,SOCCER ,DATA analysis ,PROFESSIONAL athletes ,PHYSICAL training & conditioning ,EXERCISE intensity - Abstract
Purpose: This study was designed to quantify the daily distribution of training intensity in a group of professional soccer players in Norway based on three different methods of training intensity quantification. Methods: Fifteen male athletes (age, 24 ± 5 y) performed treadmill test to exhaustion to determine heart rate and VOs corresponding to ventilatory thresholds (VT
1 , VT2 ), maximal oxygen consumption (VO2 max) and maximal heart rate. VT1 and VT2 were used to delineate three intensity zones based on heart rate. During a 4 wk period in the preseason (N = 15), and two separate weeks late in the season (N = 11), all endurance and on-ball training sessions (preseason: N = 378, season: N= 78) were quantified using continuous heart rate registration and session rating of perceived exertion (sRPE). Three different methods were used to quantify the intensity distribution: time in zone, session goal and sRPE. Results: Intensity distributions across all sessions were similar when based on session goal or by sRPE. However, intensity distribution based on heart rate cut-offs from standardized testing was significantly different (time in zone). Conclusions: Our findings suggest that quantifying training intensity by using heart rate based total time in zone is not valid for describing the effective training intensity in soccer. The results also suggest that the daily training intensity distribution in this representative group of high level Norwegian soccer players is organized after a pattern where about the same numbers of training sessions are performed in low lactate, lactate threshold, and high intensity training zones. [ABSTRACT FROM AUTHOR]- Published
- 2011
- Full Text
- View/download PDF
44. Vitamin C Consumption Does Not Impair Training-Induced Improvements in Exercise Performance.
- Author
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Roberts, Llion A., Beattie, Kris, Close, Graeme L., and Morton, James P.
- Subjects
THERAPEUTIC use of vitamin C ,REACTIVE oxygen species ,ACTIVE oxygen in the body ,ANALYSIS of variance ,ANTIOXIDANTS ,ATHLETIC ability ,COMPUTER software ,DIETARY supplements ,EXERCISE tests ,REGRESSION analysis ,RUNNING ,DATA analysis ,BODY movement ,RANDOMIZED controlled trials ,BLIND experiment ,EXERCISE intensity - Abstract
Purpose: To test the hypothesis that antioxidants can attenuate high-intensity interval training-induced improvements in exercise performance. Methods: Two groups of recreationally active males performed a high-intensity interval running protocol, four times per week for 4 wk. Group 1 (n = 8) consumed 1 g of vitamin C daily throughout the training period, whereas Group 2 (n = 7) consumed a visually identical placebo. Pre- and posttraining, subjects were assessed for VO
2 max, 10 km time trial, running economy at 12 km/h and distance run on the YoYo intermittent recovery tests level 1 and 2 (YoYoIRTl/2). Subjects also performed a 60 min run before and after training at a running velocity of 65% of pretraining VO2max so as to assess training-induced changes in substrate oxidation rates. Results: Training improved (P < .0005) VO2 max, 10 km time trial, running economy, YoYolRTl and YoYolRT2 in both groups, although there was no difference (P = .31,0.29,0.24,0.76 and 0.59) between groups in the magnitude of training-induced improvements in any of the aforementioned parameters. Similarly, training also decreased (P < .0005) mean carbohydrate and increased mean fat oxidation rates during submaximal exercise in both groups, although no differences (P = .98 and 0.94) existed between training conditions. Conclusions: Daily oral consumption of 1 g of vitamin C during a 4 wk high-intensity interval training period does not impair training-induced improvements in the exercise performance of recreationally active males. [ABSTRACT FROM AUTHOR]- Published
- 2011
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45. Blood Lactate Diagnostics in Exercise Testing and Training.
- Author
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Beneke, Ralph, Leithäuser, Renate M., and Ochentel, Oliver
- Subjects
ACTIVE oxygen in the body ,BIOMARKERS ,LACTATES ,TIME ,ANAEROBIC threshold ,PHYSICAL training & conditioning ,EXERCISE intensity - Abstract
A link between lactate and muscular exercise was seen already more than 200 years ago. The blood lactate concentration (BLC) is sensitive to changes in exercise intensity and duration. Multiple BLC threshold concepts define different points on the BLC power curve during various tests with increasing power (INCP). The INCP test results are affected by the increase in power over time. The maximal lactate steady state (MLSS) is measured during a series of prolonged constant power (CP) tests. It detects the highest aerobic power without metabolic energy from continuing net lactate production, which is usually sustainable for 30 to 60 min. BLC threshold and MLSS power are highly correlated with the maximum aerobic power and athletic endurance performance. The idea that training at threshold intensity is particularly effective has no evidence. Three BLC-orientated intensity domains have been established: (I) training up to an intensity at which the BLC clearly exceeds resting BLC, light- and moderate-intensity training focusing on active regeneration or high-volume endurance training (Intensity < Threshold); (2) heavy endurance training at work rates up to MLSS intensity (Threshold ≤ Intensity ≤ MLSS); and (3) severe exercise intensity training between MLSS and maximum oxygen uptake intensity mostly organized as interval and tempo work (Intensity > MLSS). High-performance endurance athletes combining very high training volume with high aerobic power dedicate 70 to 90% of their training to intensity domain 1 (Intensity < Threshold) in order to keep glycogen homeostasis within sustainable limits. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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46. Metabolic Profile of the Ironman World Championships: A Case Study.
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Cuddy, John S., Slivka, Dustin R., Hailes, Walter S., Dumke, Charles L., and Ruby, Brent C.
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ACTIVE oxygen in the body ,ANALYSIS of variance ,ANTHROPOMETRY ,BIOPSY ,CYCLING ,ENERGY metabolism ,MUSCLES ,REGRESSION analysis ,RESEARCH funding ,RUNNING ,SPECTROPHOTOMETRY ,TRIATHLON ,WATER in the body ,SPORTS events ,ELITE athletes ,REPEATED measures design - Abstract
Purpose: The purpose of this study was to determine the metabolic profile during the 2006 Ironman World Championship in Kailua-Kona, Hawaii. Methods: One recreational male triathlete completed the race in 10:40:16. Before the race, linearregression models were established from both laboratory and field measures to estimate energy expenditure and substrate utilization. The subject was provided with an oral dose of 2H2 18O approximately 64 h before the race to calculate total energy expenditure (TEE) and water turnover with the doubly labeled water (DLW) technique. Body weight, blood sodium and hematocrit, and muscle glycogen (via muscle biopsy) were analyzed pre- and postrace. Results: The TEE from DLW and indirect calorimetry was similar: 37.3 MJ (8,926 kcal) and 37.8 MJ (9,029 kcal), respectively. Total body water turnover was 16.6 L, and body weight decreased 5.9 kg. Hematocrit increased from 46 to 51% PCV. Muscle glycogen decreased from 152 to 48 mmoL/kg wet weight pre- to postrace. Conclusion: These data demonstrate the unique physiological demands of the Ironman World Championship and should be considered by athletes and coaches to prepare sufficient nutritional and hydration plans. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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47. Hypoxia Increases Muscle Hypertrophy Induced by Resistance Training.
- Author
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Nishimura, Akinobu, Sugita, Masaaki, Kato, Ko, Fukuda, Aki, Sudo, Akihiro, and Uchida, Atsumasa
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ACTIVE oxygen in the body ,ANALYSIS of variance ,HYPOXEMIA ,ANTHROPOMETRY ,ENVIRONMENTAL engineering of buildings ,EXERCISE ,HYPERTROPHY ,MAGNETIC resonance imaging ,MUSCLE strength ,STATISTICS ,T-test (Statistics) ,DATA analysis ,RANDOMIZED controlled trials - Abstract
Purpose: Recent studies have shown that low-intensity resistance training with vascular occlusion (kaatsu training) induces muscle hypertrophy. A local hypoxic environment facilitates muscle hypertrophy during kaatsu training. We postulated that muscle hypertrophy can be more efficiently induced by placing the entire body in a hypoxic environment to induce muscle hypoxia followed by resistance training. Methods: Fourteen male university students were randomly assigned to hypoxia (Hyp) and normoxia (Norm) groups (n = 7 per group). Each training session proceeded at an exercise intensity of 70% of 1 repetition maximum (RM), and comprised four sets of 10 repetitions of elbow extension and flexion. Students exercised twice weekly for 6 wk and then muscle hypertrophy was assessed by magnetic resonance imaging and muscle strength was evaluated based on 1RM. Results: Muscle hypertrophy was significantly greater for the Hyp-Ex (exercised flexor of the hypoxia group) than for the Hyp-N (nonexercised flexor of the hypoxia group) or Norm-Ex flexor (P < .05, Bonferroni correction). Muscle hypertrophy was significantly greater for the Hyp-Ex than the Hyp-N extensor. Muscle strength was significantly increased early (by week 3) in the Hyp-Ex, but not in the Norm- Ex group. Conclusion: This study suggests that resistance training under hypoxic conditions improves muscle strength and induces muscle hypertrophy faster than under normoxic conditions, thus representing a promising new training technique. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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48. Letters to the Editor.
- Author
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Boullosa, Daniel A., Nakamura, Fábio Y., Ruiz, Jonatan R., Seiler, Stephen, Esteve-Lanao, Jonathan, Lucia, Alejandro, Hawley, John A., and Martin, David T.
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ACTIVE oxygen in the body ,ATHLETIC ability ,GENETICS ,PHYSICAL fitness ,ROWING ,PHYSICAL training & conditioning ,EXERCISE intensity - Abstract
A letter to the editor is presented by Daniel A. Boullosa, Fábio Y. Nakamura, and Jonatan R. Ruiz, confirming the effectiveness of “polarized training” for rowing performance, which in turn has elicited several responses.
- Published
- 2010
- Full Text
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49. An Attempt to Quantify the Placebo Effect From a Three-Week Simulated Altitude Training Camp in Elite Race Walkers.
- Author
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Saunders, Philo U., Ahlgrim, Christoph, Vallance, Brent, Green, Daniel J., Robertson, Eileen Y., Clark, Sally A., Schumacher, Yorck O., and Gore, Christopher J.
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ACTIVE oxygen in the body ,ANALYSIS of variance ,HYPOXEMIA ,ATHLETIC ability ,BLOOD testing ,CARDIOPULMONARY system ,EXERCISE tests ,PLACEBOS ,T-test (Statistics) ,TIME ,WALKING ,PHYSICAL training & conditioning ,RANDOMIZED controlled trials ,ELITE athletes ,BLIND experiment - Abstract
Purpose: To quantify physiological and performance effects of hypoxic exposure, a training camp, the placebo effect, and a combination of these factors. Methods: Elite Australian and International race walkers (n = 17) were recruited, including men and women. Three groups were assigned: 1) Live High:Train Low (LHTL, n = 6) of 14 h/d at 3000 m simulated altitude; 2) Placebo (n = 6) of 14 h/d of normoxic exposure (600 m); and 3) Nocebo (n = 5) living in normoxia. All groups undertook similar training during the intervention. Physiological and performance measures included 10-min maximal treadmill distance, peak oxygen uptake (VO2peak), walking economy, and hemoglobin mass (Hbmass). Results: Blinding failed, so the Placebo group was a second control group aware of the treatment. All three groups improved treadmill performance by approx. 4%. Compared with Placebo, LHTL increased Hbmass by 8.6% (90% CI: 3.5 to 14.0%; P = .01, very likely), VO2peak by 2.7% (-2.2 to 7.9%; P = .34, possibly), but had no additional improvement in treadmill distance (-0.8%, -4.6 to 3.8%; P = .75, unlikely) or economy (-8.2%, -24.1 to 5.7%; P = .31, unlikely). Compared with Nocebo, LHTL increased Hbmass by 5.5% (2.5 to 8.7%; P = .01, very likely), VO2peak by 5.8% (2.3 to 9.4%; P = .02, very likely), but had no additional improvement in treadmill distance (0.3%, -1.9 to 2.5%; P = .75, possibly) and had a decrease in walking economy (-16.5%, -30.5 to 3.9%; P = .04, very likely). Conclusion: Overall, 3-wk LHTL simulated altitude training for 14 h/d increased Hbmass and VO2peak, but the improvement in treadmill performance was not greater than the training camp effect. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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50. A Comparison of the Physiological Demands of Wheelchair Basketball and Wheelchair Tennis.
- Author
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Croft, Louise, Dybrus, Suzanne, Lenton, John, and Goosey-Tolfrey, Victoria
- Subjects
ACTIVE oxygen in the body ,ANALYSIS of variance ,BASKETBALL ,COMPUTER software ,EXERCISE tests ,HEART beat ,LACTATES ,REGRESSION analysis ,T-test (Statistics) ,TENNIS ,TIME ,WHEELCHAIR sports ,WORK measurement ,DATA analysis ,ELITE athletes ,BLOOD ,PHYSIOLOGY - Abstract
Purpose: To examine the physiological profiles of wheelchair basketball and tennis and specifically to: (a) identify if there are differences in the physiological profiles of wheelchair basketball and tennis players of a similar playing standard, (b) to determine whether the competitive physiological demands of these sports differed (c) and to explore the relationship between the blood lactate [Bla
- ] response to exercise and to identify the sport specific heart rate (HR) training zones. Methods: Six elite athletes (4 male, 2 female) from each sport performed a submaximal and VO2peak test in their sport specific wheelchair. Heart rate, VO2 , and [Bla- ] were measured. Heart rate was monitored during international competitions and VO2 was calculated from this using linear regression equations. Individual HR training zones were identified from the [Bla- ] profile and time spent within these zones was calculated for each match. Results: Despite no differences in the laboratory assessment of HRpeak, the VO2 peak was higher for the basketball players when compared with the tennis players (2.98 ± 0.91 vs 2.06 ± 0.71; P = .08). Average match HR (163 ± 11 vs 146 ± 16 beats·min-1; P = .06) and average VO2 (2.26 ± 0.06 vs 1.36 ± 0.42 L·min-1; P = .02) were higher during actual playing time of basketball when compared with whole tennis play. Consequently, differences in the time spent in the different training zones within and between the two sports existed (P < .05). Conclusions: Wheelchair basketball requires predominately high-intensity training, whereas tennis training requires training across the exercise intensity spectrum. [ABSTRACT FROM AUTHOR]- Published
- 2010
- Full Text
- View/download PDF
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