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To quantify the mechanical work of breathing (Wb) during an indoor rowing test in men and women. Additionally, to compare sex-based differences in the Wb and its components through a rowing test. Fifteen collegiate rowers were recruited (8 women/7 men) and performed a 2000 m rowing test on a rowing ergometer. Esophageal pressure was measured during exercise via balloon catheterization, after which pressure–volume curves were used to calculate total, inspiratory resistive and elastic, and total expiratory Wb. Men had significantly higher values of instantaneous and cumulative total Wb at and beyond 37.5% (430.4 ± 42.5 vs. 282.1 ± 45.1 J min−1, P

High-intensity intermittent training (HIIT) has increased in popularity due to being time-efficient mode of exercise. Previous HIIT studies have mainly focused on percentage of fat loss, fat mass loss, and weight loss. However, enhancing muscle protein synthesis induced by HIIT that results in muscular morphological adaptations is a potential benefit of HIIT. This study compared the effects of two HIIT protocols on muscular morphological adaptations.Thirty-four recreationally active participants were randomly assigned to 10-5-HIIT and 20-10-HIIT to complete 6 sets of 6 intervals. The 10-5-HIIT and 20-10-HIIT protocols were performed with 10s:5s and 20s:10s exercise-to-rest ratios and provided with 1- and 2-min recovery periods between sets, respectively. Muscle cross-sectional area (mCSA) and echo intensity (EI) of the rectus femoris (RF) and vastus lateralis (VL) were assessed via B-mode ultrasonography before and after intervention. Two-way mixed factorial ANOVAs were used for analyses.The 10-5-HIIT and 20-10-HIIT groups significantly (P0.05) increased RF mCSA (change (Δ)=0.4±0.8 cm2, 8.0%; Δ=0.5±0.8 cm2, 5.5%) and VL mCSA (Δ=1.2±1.6 cm2, 9.0%; Δ=2.20±1.4 cm2, 10.4%), respectively. No significant (P0.05) change was observed for the EI of the RF and VL.Whole-body HIIT can be a time-efficient exercise modality to elicit muscular morphological adaptations in the RF and VL muscles. The 10-5-HIIT protocol induced benefits comparable to those of the 20-10-HIIT, while it reduced the total exercise time by 50%.

Objective. The hypothalamic arcuate nucleus proopiomelanocortin (POMC) and neuropeptide Y (NPY) circuitries are involved in the inhibition and stimulation of the appetite, respectively. The aim of this study was to investigate the effects of one-month lasting high-intensity exercise on the POMC mRNA and NPY mRNA expression in the above-mentioned brain structure and appetite and food intake levels. Methods. Fourteen male Wistar rats (250±50 g) were used and kept in the well-controlled conditions (22±2 °C, 50±5% humidity, and 12 h dark/light cycle) with food and water ad libitum. The rats were divided into two groups (n=7): 1) control group (C, these rats served as controls) and 2) exercised group (RIE, these rats performed a high-intensity exercise for one month (5 days per week) 40 min daily with speed 35 m/min. The total exercise time was 60 min. The body weight and food intake were recorded continuously during the experiments. Results. The results showed relative mRNA expression of POMC and NPY estimated in the hypothalamic arcuate nucleus. There were no significant differences in the NPY and POMC mRNAs expression levels and food intake between C and RIE groups. Conclusions. The present data indicate that one-month regular intensive exercise did not alter the levels of NPY and POMC mRNAs expression (as two important factors in the regulation of appetite) in the hypothalamic arcuate nucleus and food intake suggesting that this type of exercise itself is not an appropriate procedure for the body weight reduction.

Summary Objectives The aim of the present study was to verify the training session volume and the time spent at or above 90% of maximal oxygen uptake (t90VO2max) under different work and recovery settings during high-intensity intermittent training. Equipment and methods After having the maximal oxygen uptake (VO2max) and peak velocity (Vpeak) determined, eleven male runners (age: 25.45 ± 4.13 years; VO2max: 55.88 ± 1.43 ml.kg−1.min−1 and personal best in urban 5 km: 18 min: 30s ± 01 min: 25s) completed three short HIIT (30s/30s, 40s/40s e 40s/20s) at 110% of Vpeak until exhaustion. The time sustained in oxygen fractions above 90% of VO2max, total exercise time (TT), number of complete series performed (NS) and time of exercise (TE) were quantified and compared between the different sessions. Results The t90VO2max was not different between sessions (P > 0.05); in turn, the 30s/30s protocol was greater than both 40s/40s and 40s/20s at the volume variables (30s/30s, TT (s): 1463 ± 86.14, NS (n): 24.18 ± 1.48 and TE (s): 737.36 ± 41.9–40s/40s, TT (s): 1043 ± 69.39, NS (n): 12.91 ± 0.87 and TE (s): 526.45 ± 34.72–40s/20s, TT (s): 415.55 ± 30.08, NS (n): 6.72 ± 0.51 and TE (s): 281 ± 20.01). For the prescription of training sessions, the 30s/30s protocol being the most appropriate when there is the goal to increase the volume session. On the other hand, protocol 40s/20s may optimize training time when the purpose is to stimulate high oxygen fractions, as its results are like those of other protocols in t90VO2max with time reduced up to four times.

Aim To investigate the effects of 5 years of physical exercise on functional parameters among older Japanese adults who carried out water- or land-based exercise. Methods We retrospectively investigated data from 5707 medical examinations and enrolled 77 older adults into the study. Eligible participants had to be aged ≥60 years, and engaged in water-based exercise (n = 38) or a combination of water- and land-based exercise (n = 39) for at least 80% of their total exercise time for over 5 years at our fitness center. In statistical analysis, a two-way repeated-measures analysis of variance was carried out to examine the effects over time and by exercise type, and the changes in each parameter over 5 years were also compared between the two groups. Results We found significant main effects and an interaction between time and exercise type for gait speed, with an early decline in the combined exercise group, as well as significant main effects of time, showing a functional decline in grip strength, one-leg standing time and step/height ratio in both exercise types at the 5-year follow up. The 5-year changes in each parameter did not differ between the two groups despite the frequency of exercise, even though we found a negative correlation between changes in one-leg standing time and total amount of water-based exercise. Conclusion Contrary to expectations, these results suggest that regular engagement in water-based exercise, even combined with land-based exercise, might have poor long-term benefits for maintaining physical performance in older adults. Geriatr Gerontol Int 2017; 17: 2116–2123.

Pinto, N, Salassi III, JW, Donlin, A, Schroeder, J, and Rozenek, R. Effects of a 6-week upper extremity low-volume, high-intensity interval training program on oxygen uptake, peak power output, and total exercise time. J Strength Cond Res 33(5): 1295-1304, 2019-The purpose of this study was to compare the effects of upper extremity (UE) high-intensity interval training (HIIT) to UE continuous training (CT) when training at a similar intensity. Twenty participants (mean age = 23 ± 3 years) were randomly assigned to either a HIIT (n = 10) or CT (n = 10) group. Participants completed a graded exercise test (GXT) utilizing arm cranking before and after 6 weeks (2 sessions per week) of UE training. During sessions, HIIT performed 10 repetitions of 60 seconds of work at 92.3 ± 1.0% of the arm HRpeak (%aHRpeak) and 60 seconds of passive recovery (%aHRpeak = 73.0 ± 4.0%) yielding an average training intensity of 82.6 ± 1.5 %aHRpeak. CT exercised for 20 minutes at an average intensity of 81.9 ± 2.2 %aHRpeak. After training, HIIT showed greater improvement in V[Combining Dot Above]O2peak compared with CT (Δ = 4.1 ml·min·kg, 95% confidence interval [CI]: 1.3-6.9 m·min·kg, p = 0.007). Total exercise time during the posttest GXT was also improved as a result of HIIT (Δ = 1.4 minutes, 95% CI: 0.4-2.3 minutes, p = 0.008). Both groups improved peak power output, but no difference was observed between them (Δ = 3.3 W, 95% CI: -3.3 to 9.9 W, p = 0.305). For a similar time investment, HIIT seemed to improve measures of cardiopulmonary capacity and exercise time to a greater extent than CT and may be a time-efficient alternative for those who incorporate UE aerobic activity into a training program.

Background Early graft dysfunction after orthotopic heart transplantation is associated with worse survival and functional outcomes. However, the prognostic implication of acute cellular rejection (ACR) early after transplant is less well defined. Here, we analyzed the association between early ACR and post-transplant exercise capacity. Methods We performed a retrospective analysis of all heart transplant patients who underwent cardiopulmonary exercise testing (CPET) within a year of transplant at a single large academic center between 2000 and 2011. Early ACR was defined as cellular grade 2R or 3R histopathology seen on biopsy within 3 months of transplant. Exercise capacity was assessed during CPET by 1) peak VO2 and 2) total exercise time. CPET performed prior to diagnosis of rejection were excluded. The association between early ACR or grade of ACR and exercise parameters was analyzed using linear regression. Results A total of 230 patients (median age 55 [IQR 45-61], 79.6% male) who received a heart transplantation at our institution between 2000 and 2011 underwent CPET during the 1st year. Of these, 12% (n=40) developed early grade 2R rejection and 5% (n=12) developed early grade 3R rejection. No antibody mediated rejection (including hyperacute) was seen in this timeframe among patients who later underwent CPET. Neither peak VO2 (p=0.95) nor total exercise time (p=0.54) were predicted by early ACR of any grade. Conclusions Early cellular rejection does not predict worse exercise capacity in the first year after heart transplant. This inference is limited to patients who are able to undergo CPET.

Nine to 12 weeks of resistance exercise training in young individuals induces quadriceps muscle (∼6%) and region-specific patellar tendon (4-6%) hypertrophy. However, 12 weeks of resistance exercise training (∼1 h total exercise time) in older individuals (60-78 years) induces quadriceps muscle hypertrophy (9%) without impacting patellar tendon size. The current study examined if a different loading paradigm using cycle exercise would promote patellar tendon hypertrophy or alter the internal tendon properties, measured with magnetic resonance imaging signal intensity, in older individuals. Nine women (70 ± 2 years) completed 12 weeks of aerobic upright cycle exercise training (∼28 h total exercise time). Aerobic exercise training increased (P 0.05) over the 12 weeks of training. Region-specific CSA was unchanged (P > 0.05) at the proximal (-1 ± 3%) and mid regions (2 ± 2%) of the tendon but tended (P = 0.069) to increase at the distal region (5 ± 3%). Region-specific signal intensity differed along the tendon but was unchanged (P > 0.05) with training. Although more studies are needed, exercise-induced patellar tendon hypertrophy, compared with skeletal muscle, appears to be attenuated in older individuals, while the loading pattern associated with aerobic exercise seems to have more impact than resistance exercise in promoting patellar tendon hypertrophy.

Purpose The purpose of this study was to evaluate the effectiveness of a health promotion program utilizing action planning strategy for young adults. Methods A non-equivalent control group pre-post-test design was used. One hundred three university students participated in the study. Participants in the experimental group (n=51) were provided the health promotion program utilizing action planning strategy for five weeks. The program consisted of weekly sessions that included action planning and group feedback. The control group (n=52) was provided with health information every week for 5 weeks. Program outcomes, including self-efficacy, physical activity health behaviors, total exercise time per week, daily cigarette consumption, frequency of alcohol drinking per month, nutritional health behaviors, and subjective health status, were assessed at baseline and at follow-up after 5 weeks. Results The participants in the experimental group demonstrated significant increases in self-efficacy, physical activity health behaviors, weekly exercise time, and nutritional health behaviors and significant decreases in daily cigarette consumption than those in the control group. Conclusion The health promotion program utilizing action planning strategy is a brief and effective intervention to promote health behaviors among young adults. Further investigation is warranted to assess the program's effectiveness among other age groups and populations at high risk for chronic illness.

The purpose of this study was to examine energy metabolism during two simulated races (skating and classical) in cross-country skiing. In each race 15 elite subjects skied a 2.75-km track 5 times. In laps 2 and 4, the skiers were told to skate without poles in the skating race and without the diagonal stride in the classical race. The total exercise time was between 42 and 50 min in the 2 races. The oxygen uptake was measured on flat and uphill terrain during each lap and blood lactate after each lap. The relative mean oxygen uptake for classical skiing was 88% (82-96) for level and 93% (87-97) for uphill terrain. The respective means for skating were 91% (85-96) for level and 91% (81-97) for uphill terrain. The mean values and range for blood lactate at race speeds were 10.6 mM (7.1-18.1) and 9.2 mM (4.8-18.8) for skating and classical, respectively. A relative steady state was achieved after the first lap, although a slight but significant blood lactate accumulation took place until finish (0.04-0.06 mM min−1). The respiratory exchange ratio in both skiing styles varied between 0.88-0.90 and 0.92-0.93 for flat and uphill terrain, respectively, indicating a large lipid oxidation at these very high exercise intensities.

LUCIA, A., J. HOYOS, A. SANTALLA, C. EARNEST, and J. L. CHICHARRO. Tour de France versus Vuelta a Espana: Which Is Harder? Med. Sci. Sports Exerc., Vol. 35, No. 5, pp. 872- 878, 2003. Purpose: To compare the total exercise loads (intensity volume) of the Vuelta a Espana and Tour de France during the last year. Methods: Seven professional road cyclists (28 1 yr; V u O2max: 74.6 2.2 mL·kg 1 ·min 1 ) who participated in both Tour and Vuelta during the years 1997, 1999, 2000, or 2001 were collected as subjects. They wore a heart rate (HR) telemeter during each stage of the two races, and exercise intensity was divided into three phases according to the reference HR values obtained during a previous ramp cycle-ergometer test: phase I (ventilatory threshold (VT)), phase II (between VT and the respiratory compensation point (RCP)) and phase III (RCP). Total volume and intensity were integrated as a single variable. The score for volume intensity in each phase was computed by multiplying the accumulated duration in this phase by a multiplier for this particular phase. The total score for Tour and Vuelta was obtained by summating the results of the three phases. Results: The total loads (volume intensity) did not significantly differ between the two races ( P 0.05), despite a significantly longer total exercise time of the Tour (P 0.05) (5552 176 vs 5086 290 min). Conclusion: The physiological loads imposed on cyclists' bodies do not differ between the Tour and Vuelta, despite the longer duration of daily stages in the former race. Key Words: CYCLING, VOLUME, INTENSITY, HEART RATE, TELEMETER

The purpose of this study was to determine the effect of different doses of caffeine on extending time to exhaustion in long-term endurance exercise. Using a placebo-controlled, double-blind crossover study design, 10 hobby male cyclists (30.3 ± 5.8 y; BMI = 23.5 ± 1.6, VO2max = 56.9 ± 6.6 ml x kg⁸¹ x min⁸¹) completed three experimental tests. Each test consisted of 1-h steady-state cycling on static ergometer at 70% VO2max load immediately followed by graded exercise test to exhaustion (2.3 W x s⁸¹). Either placebo or 0 or 7 mg x kg⁸¹ BM of synthetic caffeine with 0.5 l water and maximum of 0.5 mg x kg⁸¹ BM of carbohydrate gel were administered 70 minutes prior to the test. Total exercise time was significantly (p < 0.05) extended by the 7 mg x kg⁸¹ BM of caffeine compared with placebo. Significant (p < 0.05) extension of total exercise time was observed also by the 7 mg x kg⁸¹ compared with 2 mg x kg⁸¹. No statistically (p = 0.97) significant differences were observed between 2 mg x kg⁸¹ compared with placebo. Positive effect of caffeine on long-term endurance in hobby cyclist was observed only after ingestion of high dosage (7 mg x kg⁸¹ BM). Low dosage (2 mg x kg⁸¹) didn’t show any ergogenic effect compared with placebo. This result might not be generalized, but rather shows ambiguous effects of this substance.

From November 1994 to October 1995, 63 patients (average age 66 years; 41 men) from 15 centers implanted with the Biotronik Dromos DR and Ergos TC 03 pulse generators were prospectively screened with an exercise test in the DDD mode for the presence of chronotropic incompetence (CI). Both pulse generators incorporate an identical accelerometer-based motion sensor. CI was defined as a maximum heart rate < 60% of age predicted maximum heart rate or 100 beats/min. Twenty-five patients (40%) met the criteria for CI. Two weeks later, CI patients were required to complete paired metabolic exercise testing in the DDD and DDDR modes on consecutive days with a 24-hour rest period. The order of testing was randomized and performed double blinded to minimize potential biases. Three patients who did not reach the anaerobic threshold (AT) and one patient who was unable to perform the metabolic testing were excluded from the analysis. Compared to the DDD mode, there were statistically significant improvements in the DDDR mode for all five endpoints: heart rate (84 +/- 3.6 vs 113 +/- 3.5 beats/min; P < 0.0001); total exercise time (8.23 +/- 0.71 vs 9.15 +/- 0.65 min; P = 0.0005); maximum VO2 (17.76 +/- 1.36 vs 20.43 +/- 1.75 mL/kg per min; P = 0.0001); VO2 at AT (13.1 +/- 0.87 vs 14.59 +/- 0.79 mL/kg per min; P < 0.01); and exercise time to AT (5.65 +/- 0.61 vs 6.33 +/- 0.53 min; P = 0.02). In conclusion, the results of paired metabolic exercise tests with the Dromos DR and Ergos TC 03 pulse generators demonstrate a clear clinical benefit using the accelerometer-based sensor in the CI patient.

This study aimed to use the intermittent critical velocity (ICV) model to individualize intermittent exercise and analyze whether a fast-start strategy could increase the time spent at or above 95 %VO(2max) (t95VO(2max)) during intermittent exercise. After an incremental test, seven active male subjects performed three intermittent exercise tests until exhaustion at 100, 110, and 120 % of the maximal aerobic velocity to determine ICV. On three occasions, the subjects performed an intermittent exercise test until exhaustion at 105 % (IE105) and 125 % (IE125) of ICV, and at a speed that was initially set at 125 %ICV but which then decreased to 105 %ICV (IE125-105). The intermittent exercise consisted of repeated 30-s runs alternated with 15-s passive rest intervals. There was no difference between the predicted and actual Tlim for IE125 (300 ± 72 s and 284 ± 76 s) and IE105 (1,438 ± 423 s and 1,439 ± 518 s), but for IE125-105 the predicted Tlim underestimated the actual Tlim (888 ± 211 s and 1,051 ± 153 s, respectively). The t95VO(2max) during IE125-105 (289 ± 150 s) was significantly higher than IE125 (113 ± 40 s) and IE105 (106 ± 71 s), but no significant differences were found between IE125 and IE105. It can be concluded that predicting Tlim from the ICV model was affected by the fast-start protocol during intermittent exercise. Furthermore, fast-start protocol was able to increase the time spent at or above 95 %VO2max during intermittent exercise above ICV despite a longer total exercise time at IE105.

Objectives: The aim of this study was to evaluate the safety and efficacy of spinal cord stimulation (SCS) for refractory angina. Materials and Methods: This multicenter, randomized, single-blind, controlled trial evaluated SCS in two patient groups: high stimulation (HS) (treatment) and low stimulation (LS) (control). The HS group controlled SCS with a programmer for a minimum of two hours four times daily. The LS group received SCS therapy above the paresthesia threshold for one min once daily. The primary efficacy endpoint was number of angina attacks recorded by patients at six months. The primary safety endpoint was the major adverse cardiac event (MACE) rate at six months. Results: Due to slow enrollment, a futility analysis was performed, resulting in early termination of the study. Sixty-eight patients were randomized after implantation. Mean change in angina attacks per day from baseline to six months was −1.19 ± 2.13 (HS) and −1.29 ± 1.66 (LS). The difference from baseline was significant within each group (both p

Introduction Mangalarga Marchador (MM) is the most important Brazilian horse breed. Functional evaluation of MM horses is performed in marcha competitions, where horses must perform 4-gaited exercise at 13 km/h for 70 min. The aim of this work was to test a training protocol to prepare MM horses for marcha competition. Methods Eight untrained MM mares, in randomized blocks with Split plots, were trained for 84 days. Three days/week horses were ridden for one hour (10 min walk, then an individual amount of marcha exercise at 13 km/h established in a previous test, then walk to complete one hour total exercise time). Two days/week, horses walked for one hour. Before training and every 21 days a marcha test (MT) was performed, totaling 5 tests in the experimental period. During the MT, mares were exercised at 13 km/h using a heart rate monitor. Every 10 min heart rate (HR) and blood lactate concentration [La] were recorded. The MT was stopped at 70 min of exercise, or if HR was ≥150 bpm and [La] was ≥4 mmol/L, or if Marcha Time was reached. Blood samples for hemogram, lactate, glucose, triglyceride and CK, LDH, AST determination were collected. Individual time used for training was 10 min less than the exercising time in the previous MT. Regression was used to analyze the results. Results From MT 1 to 4, the positive effect of training was shown on HR, [La] and marcha time (from 9.52 min to 70.5 min, CV = 26.41). There was not an increase in marcha time on test 5. Conclusions MM mares trained for 63 days with the described protocol are ready to compete in marcha competition. Ethical Animal Research The study was approved by the Ethical Animal (CETEA) of the UFMG with the 255/11 protocol. Sources of funding: CNPq, CAPES, FAPEMIG, ABCCMM, Haras Catuni e Racoes Total. Competing interests: none.

This pilot study examined the effectiveness of a telephone-based intervention to increase physical activity in obese African American women with mobility disabilities by targeting the removal of barriers to participation.Severely obese (mean body mass index [BMI] = 49.1 kg.m²) African American women (n = 33) with mobility disabilities completed a 6-month telephone-based physical activity coaching intervention.The major environmental/facility barriers at preintervention were cost of the program (66.7%), lack of transportation (48.5%), not aware of fitness center in the area (45.5%), and lack of accessible facilities (45.5%). The major personal barriers were pain (63.6%), don't know how to exercise (45.5%), health concerns (39.4%), don't know where to exercise (39.4%), and lack of energy (36.4%). Despite only two personal barriers being significantly lower at posttest (don't know where to exercise and don't know how to exercise) (p0.01), total exercise time increased from6 minutes/day to 27 minutes/day at posttest (p0.001), and total physical activity time (structured exercise, leisure, indoor and outdoor household activity) increased from 26 minutes/day to 89 minutes/day at posttest (p0.001).Interventions aimed at increasing physical activity participation among obese African American women with mobility disabilities should start with increasing their awareness/knowledge on where and how to exercise. Other reported barriers (e.g., cost, transportation, finding an accessible facility, health concerns, pain) may not be as critical to alter/remove as identifying where participants can exercise (i.e., home, outdoors, gym) and providing them with a variety of routines that can be performed safely in their desired setting.

Background The protocol and the duration of an exercise test have considerable influence on peak oxygen consumption (Vo 2 ). On a bicycle ergometer, the use of a ramp protocol with a target exercise duration of 8 to 12 minutes is recommended to reliably measure maximal oxygen uptake. Because of cardiac denervation, heart transplant recipients have a delayed heart rate adaptation to exercise, and oxygen uptake kinetics are altered. Methods We investigated whether the rate of workload increase during exercise testing would influence peak Vo 2 after heart transplantation. Two symptom-limited exercise tests, applying a ramp and a 3-minute step protocol were effectuated on a bicycle ergometer. Results Seventeen patients (14 men, 3 women), mean age 58.4 ± 12.7 years, at 64.5 ± 26.7 months post-transplant participated in the study. No statistically significant differences between the 2 protocols were found regarding total exercise duration until exhaustion (8:42 ± 2:09 vs 8:48 ± 2:27 minutes, p = 0.705), maximal workload reached (117.9 ± 42.6 vs 106.4 ± 40.5 W; p = 0.055), peak heart rate (135.8 ± 11.6 vs 131.2 ± 14.8 beats/min.; p = 0.061), and peak Vo 2 (20.9 ± 5.2 vs 20.5 ± 5.9 ml/kg/min; p = 0.538). Conclusions Peak Vo 2 seems insensitive to a stepwise or ramping exercise protocol in heart transplant patients when the workload increments are chosen in a way that a total exercise time of 8 to 12 minutes is achieved. Both protocols can therefore be applied to evaluate peak Vo 2 .

The exercise volume and intensity are reported of a male professional cyclist (age 30; VO2MAX 75.0 ml/kg/min) who successfully completed the 2001 Giro d'Italia (May), Tour de France (July), and Vuelta a España (September). The total exercise time during the Giro, Tour, and Vuelta was 90 hours 44 minutes (5444 minutes), 88 hours 23 minutes (5303 minutes), and 72 hours 59 minutes (4379 minutes) respectively. Heart rate telemetry during the races allowed the exercise intensity to be classified into three phases: I, below the first ventilatory threshold (VT1); II, between VT1 and the second ventilatory threshold (VT2); III, above VT2. Compared with the Giro and Tour, the lower exercise volume of the Vuelta (about 20% less total time) was compensated for by a considerably lower and higher contribution of phases I and III respectively. As a result, the total load (volume x intensity) in the three races was comparable. Sin financiación 1.253 JCR (2003) Q1, 17/71 Sport sciences UEM

This study investigated the effect of initial muscle glycogen on performance of repeated sprints and some potential mechanisms for an effect of glycogen on fatigue. Eight subjects performed 2 cycling trials (repeated 60-s sprints) following consumption of either a high carbohydrate (HC) or a low carbohydrate (LC) diet. Muscle biopsies and blood samples were collected at baseline, following a 15% (15% fatigue) and a 30% decline in sprint performance (30% fatigue), when exercise was terminated. Baseline muscle glycogen levels [346 ± 19 HC (SEM) vs. 222 ± 19 mmol/kg dw LC] and total exercise time to 30% fatigue were higher following HC than LC (57.5 ± 10.0 vs. 42.0 ± 3.6 min; p < .05). Similar significant (p < .05) decreases over the entire exercise bout were seen in muscle glycogen (43%), creatine phosphate (CP; 35%), and sarcoplasmic reticu-lum (SR) Ca2+-uptake in isolated homogenized muscle (56%) for both trials (p > .05 between trials). The percentage decline in SR Ca2+-release was less for HC than LC (36% and 53%, respectively), but this was not statistically different. In summary, HC delayed fatigue during repeated sprints. As the reductions in muscle glycogen, CP, and SR function during exercise were not different by dietary treatment, these data do not support a link between whole muscle glyco-gen and SR function or CP reduction during repeated sprint exercise.

This study investigated the suitability of our oxygen pulse reserve (OPR) method for tailoring parameters of rate responsive pacemakers and planning aerobic rehabilitation programs. We selected 11 patients, NYHA Classes I-III (7 males and 4 females; mean age 60 years, range 18-83), with rate responsive pacemakers implanted for high degree AV block and chronotropic incompetence. Five pacemakers had activity sensors, 4 had temperature sensors, and 2 had dual sensors. All patients underwent a cardiopulmonary stress test (CPX). We determined anaerobic threshold time (ATT), VO2/AT, total exercise time (TET), VO2 Max, and VO2 AT/VO2 Max. OPR (mL-O2/beat) was calculated for each patient using the formula OPR = (VO2 Max - VO2 resting)/(HR Max - HR resting). During CPX, this slope was used as the rate response tailoring guideline by comparing the mL-O2/beat equation and the pacing rate. Rate response settings were modified until the optimal relationship between theoretical and paced rate was obtained. The work protocol yielded rate response settings capable of providing pacing rates within +/- 10 beats of the theoretical values. Data relating to theoretical and measured rates have been analyzed statistically. Patients underwent an aerobic rehabilitation program that followed the American College of Sports Medicine guidelines. Pacing rate at the anaerobic threshold was considered the border for an aerobic workload. After 2-7 months, all patients showed an evident improvement in ATT (92%), VO2/AT (48%), TET (49%), VO2 Max (23%), and VO2 AT/VO2 (21%). Particularly, two patients improved from Weber Class C to A, and three improved from C to B. At each CPX step, the mean values of pacing rate and theoretical rate almost overlap, and the relevant coefficients suggest an excellent correlation (P < 0.001). Our OPR method for tailoring rate response provides the basis for an effective rehabilitation program with functional advantages for patients.

To demonstrate physiologic changes associated with asthma symptoms that many patients with asthma develop during exercise, we used sustained constant-load and interval exercise protocols with subjects breathing dry room temperature air. In constant-load exercise, subjects pedaled a stationary bicycle at 50% of their maximal power capacity for 36 min. In interval protocols, subjects pedaled at 60% of maximal capacity for 6 min and then 40% of maximal for 6 min; the 12-min cycle was repeated three times for a total exercise time of 36 min. Maximal expiratory flow versus volume maneuvers (MEFV) were obtained before, at 6-min intervals during, and at 5-min intervals after exercise. Changes in peak expiratory flow (PEF), forced expiratory volume in 1 s (FEV1), and forced expiratory flow at 50% of pre-exercise vital capacity (FEF50) were compared with pre-exercise values. Within 15 min after a maximal 1-min incremental exercise protocol, mean flows decreased compared with pre-exercise (PEF, mean -22%, range -46 to 5%; FEV1, mean -21%, range -42 to -3%; FEF50, mean -41%, range -80 to 3%; all p0.05). There were no significant changes in MEFV flows until 18 min of constant-load exercise, when FEV1 and FEF50 fell (FEV1, mean -6%, range -15 to 2%; FEF50, mean -14%, range -32 to 6%; both p0.05), although changes in PEF were minimal and were not significantly different compared with pre-exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid depletion of muscle glycogen occurs during activities greater than 100% of maximal oxygen uptake. While carbohydrate ingestion prior to an endurance event has been shown to be beneficial, the effects of carbohydrate ingestion on repeated bouts of high-intensity exercise are not known. Therefore, the purpose of this study was to determine if carbohydrate ingestion prior to repeated bouts of high-intensity, short-duration exercise would improve performance. Ten well-trained male cyclists performed two experimental rides, one 15 min after consumption of 5.0 ml.kg-1 body weight of a 19.7% carbohydrate drink and one following a placebo. The experimental ride consisted of four 1.6 km timed performance rides separated by 4.8 km steady-state rides at 80% of maximal oxygen uptake (between the last two performance rides the steady-state rides were 1.6 km at 80% and 1.6 km at 90%). Blood glucose levels were significantly increased following both the ingestion of the carbohydrate beverage and the performance of the exercise bout. Total exercise time following ingestion of the experimental drink [mean (SD); 25.6 (3.3) min] was not different from that following ingestion of the placebo [25.2 (3.3) min]. Similarly, the sum of all four timed performance rides following ingestion of the experimental drink [6.8 (0.9) min] was not different from that following ingestion of the placebo [6.6 (0.9) min]. In the present study, carbohydrate ingestion 15 min prior to exercise increased blood glucose levels, although performance time was not affected.

The influence of work intensity and duration on the white blood cell (WBC), lymphocyte (L) and platelet (P) count response to exercise was studied in 16 trained subjects (22±5.4 years, \(\bar x\)±SD). They performed three cyclo-ergospirometric protocols: A) 10 min at 150 W followed by a progressive test (30 W/3 min) till exhaustion; B) constant maximal work (\(\dot V_{{\text{O}}_{\text{2}} {\text{max}}}\)); C) a 45 min Square-Wave Endurance Exercise Test (SWEET), (n=5). Arterial blood samples were taken: at rest, submaximal and maximal exercise in A; maximal exercise in B; 15th, 30th and 45th min in the SWEET. Lactate, [H+], PaCO2, PaO2, [Hct], Hb, cortisol, ACTH, total platelet volume (TPV), total blood red cell (RBC), WBC, L and P were measured. At 150 W, WBC, L, P, and TPV increased. \(\dot V_{{\text{O}}_{\text{2}} {\text{max}}}\) did not differ between A and B, but a difference was found in total exercise time (A=25±3 min; B=7±2 min, p

Age and physical inactivity are important risk factors for cardiovascular mortality. Heart rate response to exercise (HRRE) and heart rate recovery (HRR), measures of cardiac autonomic function, are strong predictors of mortality. The present study defined the effect of age and physical activity on HRRE and HRR. Healthy women (N=72) grouped according to age (young, 20-30 years; middle, 40-50 years; and older, 65-81 years) and daily physical activity (low active 12,500 steps/day) performed a maximal cardiopulmonary exercise test. The HRRE was defined as an increase in heart rate from rest to 1, 3 and 5 minutes of exercise and at 1/3 of total exercise time, and HRR as the difference in heart rate between peak exercise and 1, 2, and 3 minutes later. Age was associated with a significant decline in HRRE at 1 min and 1/3 of exercise time (r=-0.27, p=0.04, and r=-0.39, p=0.02) and HRR at 2 min and 3 min (r=-0.35, p=0.01, and r=-0.31, p=0.02). There was no significant difference in HRRE and HRR between high and low-active middle-age and older women (p>0.05). Increased level of habitual physical activity level appears to have a limited effect on age-related decline in cardiac autonomic function in women.