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We examined the effects of adding a Kettlebell Swing training program (KB) to the regular skill-training protocol (REGULAR) on cardiorespiratory fitness, cardiorespiratory/metabolic demand, and recovery to a simulated competition of female artistic gymnastics. Nine gymnasts (13±2 years) had their REGULAR complemented with a 4-week kettlebell training (REGULAR+KB), consisting of 3 sessions/week of 12x30" swings x 30" rest with ¼ of their body weight, while 9 aged-matched gymnasts acted as a comparison group. Peak oxygen uptake ([Formula: see text]) during routines was estimated from the O2 recovery curve using backward extrapolation and off-kinetics parameters were modeled through a mono-exponential function. Heart rate (HR) was monitored continuously and capillary blood lactate (BLa-) was measured before and after each routine (1st and 3rd min). Cardiorespiratory fitness ([Formula: see text]) was evaluated using a ramp cycle ergometer test. A training-by-time interaction effect was observed for [Formula: see text] (p = 0.009) as increments were only observed after REGULAR+KB (M = 8.85, SD = 9.67 ml.kg.min-1). No training-by-time interactions were observed for HRpeak (p = 0.39), [Formula: see text] (p = 0.07), or La-post3 (p = 0.25), both training protocols reduced HRpeak (M = -12; SD = 11 b.min-1) and BLa-post1 (M = -0.70; SD = 1.29 mmol.L-1) during the simulated competition, but not relative [Formula: see text]. No training-by-time interaction was observed for the off-transient [Formula: see text] time constant (p = 0.38). [Formula: see text] recovery was slower (M = 5; SD = 10 s) after both protocols. Both training protocols improved cardiorespiratory and metabolic demands and recovery kinetics to a simulated competition of female artistic gymnastics, although increases in cardiorespiratory fitness were only observed in REGULAR+KB., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Melo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Introduction: Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with a prevalence of nearly 1 million adults in the United States. MS results in declines in physical activity and peak oxygen consumption that might be independently associated with declines in walking performance. Therefore our purpose was to evaluate the association between physical activity and peak oxygen consumption with walking performance in individuals with MS., Methods: Fifty individuals with MS between the ages of 18-70 yrs. (Female: 38; 46  ±  12 yrs.; BMI: 28.5  ±  6.4; EDSS: 3.3 [IQR: 2.5-4]) performed a maximal incremental cycle test to assess peak oxygen consumption (VO 2peak ), and wore an accelerometer for one week to measure moderate-to-vigorous physical activity (MVPA). Subjects further completed a timed 25-foot walk test (T25FW) and 6-minute walk (6MW) to measure walking performance., Results: MVPA and VO 2 peak were correlated with 6MW and T25FW (p < 0.05). When combined in multivariate regression analyses, VO 2peak and MVPA were both significant contributors of T25FW speed and 6MW, but after controlling for sex and age, MVPA was the only significant contributor (β = 0.32 and β = 0.44, respectively)., Conclusion: Both higher MVPA and VO 2peak were associated with better walking performance and in a combined model physical activity, but not peak oxygen consumption, remained an independent contributor to walking performance in individuals with MS. These results suggest that improving MVPA is a potential target for interventions to improve walking performance in persons with MS., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Persons with Down syndrome (DS) have low aerobic exercise capacity. The present authors sought to compare the oxygen uptake efficiency slope (OUES) between adults with and without DS performing graded exercise testing (GXT) and to investigate its relationship with peak oxygen uptake (VO 2peak ) in both groups of participants., Method: Twenty-three participants with DS and 24 non-disabled controls performed GXT with VO 2 measurements. OUES was calculated from data of the first 75%, 90% and 100% GXT time. Multiple linear regression analyses were computed to explore associations between the independent (OUES and DS) and the dependent variables (VO 2peak )., Results: VO 2peak , GXT time and OUES were lower in participants with DS (p < .05). OUES and DS explained 69.3% of the variance in VO 2peak ., Conclusions: Our findings show that OUES values are lower in persons with DS. Additionally, it was shown that OUES has predictive value for VO 2peak estimations in DS., (© 2018 John Wiley & Sons Ltd.)

Background: When developing walking programmes for improving health in adults with Down syndrome (DS), physical activity professionals are in need of an equation for predicting energy expenditure. We therefore developed and cross-validated an equation for predicting the rate of oxygen uptake (VO 2 ; an index of energy expenditure) for adults with and without DS., Method: A total of 469 VO 2 observations during walking across different speeds were available from 54 adults with DS and 61 adults without DS., Results: Significant predictors of VO 2 were speed, speed square, group and group-by-speed interaction. Separate models for each group showed that speed and its square significantly predicted VO 2 . Absolute per cent error was small and did not differ between groups., Conclusion: Adults with DS have different VO 2 response to walking speed from persons without DS. VO 2 is predicted from speed with acceptable accuracy for persons with DS., (© 2017 John Wiley & Sons Ltd.)

Background: There is substantial evidence that exercise training improves aerobic capacity among people with multiple sclerosis (MS), but less is known about the associations between physical activity and sedentary behaviors with aerobic capacity., Objective: This study examined if objectively-measured moderate-to-vigorous (MVPA) and light (LPA) physical activity and sedentary behavior were associated with peak aerobic capacity (VO 2 peak) measured using an established protocol for conducting a maximal, incremental exercise test in persons with MS., Methods: The study involved a cross-sectional, observational study design and included 49 persons with MS. Participants wore an accelerometer around the waist during the waking hours for a 7-day period as a measure of physical activity and sedentary behaviors, and completed a maximal, incremental exercise test on an electronically-braked, computer-controlled cycle ergometer with open-circuit spirometry for measuring VO 2 peak., Results: VO 2 peak was significantly correlated with MVPA (r=0.53, p<0.001) and LPA (r=0.39, p<0.01), but not sedentary behavior (r=-0.12, p=0.44). Linear regression analysis indicated that MVPA (B=0.19, SE B=0.04, β=0.51, p<0.001) and LPA (B=0.02, SE B=0.01, β=0.30, p<0.05), but not sedentary behavior (B=-0.01, SE B=0.01, β=-0.14, p=0.26), explained significant variance in VO 2 peak (R 2 =0.40)., Conclusion: We provide the first evidence that MVPA and LPA represent concurrent correlates of VO 2 peak and both could be targeted for improving aerobic capacity in persons with MS., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Introduction: Adults with intellectual disabilities (ID) have significantly lower rates of physical activity and fitness than adults without ID. The 6-min walk test (6 MWT) is an inexpensive and simple way to test mobility and submaximal work capacity., Purpose: To evaluate the test-retest reliability and validity of the 6 MWT in adults and seniors with ID and explore factors contributing to the 6 MWT distance (6 MWD)., Methods: 46 participants with mild, moderate and severe ID levels (age=41 ± 11 years) performed the 6 MWT three times (T1; T2; T3) to determine test-retest reliability. To test validity, peak oxygen uptake (VO2 peak) was measured using a treadmill protocol. To analyze factors contributing to the 6 MWD, sex, height, fat mass % and fat free mass %, ID level, isometric leg strength and relative VO2 peak were also measured., Results: The walking distances for T1, T2 and T3 were 460.3 ± 76.9; 489.4 ± 81.2 and 491.4 ± 77.9 m, respectively. The 6 MWDs between T1-T2 and T1-T3 were significantly different (p<0.001), but T2 and T3 were not different. The intraclass correlation coefficient between T2 and T3 was 0.96 indicating high reliability. Relative VO2 peak and isometric leg strength significantly contributed to the 6 MWD (R(2)=0.55)., Conclusions: The 6 MWT is an easy, inexpensive, reliable and valid test in adults and seniors with ID. Familiarization is necessary to obtain reliable values. Relative VO2 peak and leg strength have significant impact on the distance walked., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This study compared arterial stiffness and wave reflection at rest and following maximal exercise between individuals with and without Down syndrome (DS), and the influence of body mass index (BMI), peak oxygen uptake (VO2 peak) on changes in arterial stiffness. Twelve people with DS (26.6 ± 2.6 yr) and 15 healthy controls (26.2 ± 0.6 yr) completed this study. Intima-media thickness (IMT) and stiffness of common carotid artery was examined. Hemodynamic and arterial variables were measured before and 3-min after exercise. Persons with DS had higher BMI and lower VO 2 peak than controls. IMT did not differ between groups. At rest, carotid β stiffness was significantly higher in persons with DS (P<0.05) but there was no difference in between groups for any of the other arterial stiffness measures. After exercise, persons with DS exhibited attenuated arterial stiffness responses in AIx-75, carotid β stiffness and Ep in contrast with controls (significant group-by-time interactions). When controlling for BMI and VO 2 peak, the interactions disappeared. In both groups combined, BMI was correlated significantly with carotid Ep and β at rest. VO 2 peak correlated significantly with AIx-75 and its pre-post change (r=-0.45, P=0.029; r=0.47, P=0.033, respectively). The arterial stiffness responses to maximal exercise in persons with DS were blunted, potentially reflecting diminished vascular reserve. Obesity and particularly VO 2 peak influenced these findings. These results suggest impaired vascular function in people with DS., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

We tested the hypothesis that acute inflammation may cause arterial stiffening in older adults. We further explored if high cardiorespiratory fitness may partially prevent the unfavorable effect of arterial stiffening produced by acute systemic inflammation in older adults. Using a randomized double-blind sham placebo-controlled design, forty healthy older adults were assigned to receive either an influenza vaccine or a sham vaccine. C-reactive protein and interleukin 6 (IL-6) were measured as markers of inflammation. Carotid-femoral pulse wave velocity (PWV) and augmentation index (AIX) as indices of arterial stiffness and wave reflection were assessed at baseline and 24 and 48 h after each vaccination. When compared with sham placebo, the influenza vaccination caused a significant increase in CRP (p < 0.05) and IL-6 (p < 0.05). Carotid-femoral PWV, but not AIX was significantly increased after influenza vaccination (p < 0.05), but not sham vaccination. The high cardiorespiratory fitness group had an attenuated increase in PWV as compared to the low cardiorespiratory fitness group after acute inflammation (p < 0.05). These findings show that acute inflammation may cause significant increases in arterial stiffness in older adults, but these increases were attenuated in the high cardiorespiratory fitness group as compared to the low cardiorespiratory fitness group.

Low work capacity and V˙O2peak commonly are described phenomena in Down syndrome. This is accompanied by chronotropic incompetence and a high incidence of obesity. Although many causes of low work capacity in Down syndrome have been proposed, little scientific support exists. Our working hypothesis is that autonomic dysfunction is the major contributor to the low levels of work capacity in this population.

This study examined the relationship between energy expenditure and wrist accelerometer output during walking in persons with and without Down syndrome (DS). Energy expenditure in metabolic equivalent units (METs) and activity-count rate were respectively measured with portable spirometry and a uniaxial wrist accelerometer in 17 persons with DS (age: 24.7±6.9 years; 9 women) and 21 persons without DS (age: 26.3±5.2 years; 12 women) during six over-ground walking trials. Combined groups regression showed that the relationship between METs and activity-count rate differed between groups (p<.001). Separate models for each group included activity-count rate and squared activity-count rate as significant predictors of METs (p≤.005). Prediction of METs appeared accurate based on Bland-Altman plots and the lack of between-group difference in mean absolute prediction error (DS: 17.07%; Non-DS: 18.74%). Although persons with DS show altered METs to activity-count rate relationship during walking, prediction of their energy expenditure from wrist accelerometry appears feasible.

Background: Researchers have recently advocated for the 2-minute walk (2MW) as an alternative for the 6-minute walk (6MW) to assess long distance ambulation in persons with multiple sclerosis (MS). This recommendation has not been based on physiological considerations such as the rate of oxygen consumption (V·O2) over the 6MW range., Objective: This study examined the pattern of change in V·O2 over the range of the 6MW in a large sample of persons with MS who varied as a function of disability status., Method: Ninety-five persons with clinically-definite MS underwent a neurological examination for generating an Expanded Disability Status Scale (EDSS) score, and then completion of the 6MW protocol while wearing a portable metabolic unit and an accelerometer., Results: There was a time main effect on V·O2 during the 6MW (p=.0001) such that V·O2 increased significantly every 30 seconds over the first 3 minutes of the 6MW, and then remained stable over the second 3 minutes of the 6MW. This occurred despite no change in cadence across the 6MW (p=.84)., Conclusions: The pattern of change in V·O2 indicates that there are different metabolic systems providing energy for ambulation during the 6MW in MS subjects and steady state aerobic metabolism is reached during the last 3 minutes of the 6MW. By extension, the first 3 minutes would represent a test of mixed aerobic and anaerobic work, whereas the second 3 minutes would represent a test of aerobic work during walking.

The reduced gait stability and aerobic fitness of people with Down syndrome (DS) may increase their rate of gross oxygen uptake (gross-VO(2)) during over-ground walking. If so, the ACSM equation predicting gross-VO(2) from speed may not be appropriate and an equation specifically for these individuals may be needed. This study therefore examined whether the relationship between gross-VO(2) and speed differs between individuals with and without DS during over-ground walking and attempted to develop a gross-VO(2) prediction equation for people with DS. Gross-VO(2) was measured in 18 persons with DS (24.7 ± 6.8 years; 8 men) and 22 persons without DS (25.9 ± 4.8 years; 9 men) at rest and during five over-ground walking trials, each lasting 6 min, at 0.5, 0.75, 1.0, 1.25, and 1.5 m/s. Multi-level modeling with random intercepts and slopes demonstrated significant effects of speed, group, group-by-speed interaction, and speed squared (P < 0.001). In each group, actual gross-VO(2) did not differ from gross-VO(2) predicted by the regression equation across speeds. Bland-Altman plots showed somewhat greater variability in the difference between actual and predicted gross-VO(2) for participants with DS. Mean absolute error of prediction was 10.75 and 10.67% for participants with and without DS, respectively. In participants with DS, the ACSM formula under-estimated gross-VO(2) across speeds, whereas, in participants without DS, only at 1.5 m/s (P < 0.001). Therefore, individuals with DS show altered curvilinear gross-VO(2) to speed relationship during over-ground walking. The present regression equation appears to offer accurate prediction in people with DS and could be used for prescribing over-ground walking intensities.

This study compared the validity of reported equations as predictors of peak VO(2) in 8-10-year-old children. Participants (90 boys and girls aged 8-10 years) performed the multistage-shuttle-run-test (MSRT) and peak VO(2) was measured in field using a portable gas analyser. The equations that estimated peak VO(2) from the MSRT performance were chosen according to the age range of this study. As follows, the FITNESSGRAM reports and the equations of Leger et al. (Can J Appl Sport Sci 5: 77-84, 1988), Barnett et al. (Pediatr Exerc Sci 5:42-50, 1993), Matsuzaka et al. (Pediatr Exerc Sci 16:113-125, 2004) and Fernhall et al. (Am J Ment Retard 102:602-612, 1998) were used to estimate the peak VO(2) and compared with the directly measured value. The equation of Leger et al. (Can J Appl Sport Sci 5: 77-84, 1988) provided a mean difference (d) of 4.7 ml kg(-1) min(-1) and a 1.0 slope. The equation of Matsuzaka et al. (Pediatr Exerc Sci 16:113-125, 2004)(a) using maximal speed (MS) showed a higher d (5.4) than the remaining using total laps d (4.2). The equation of Barnett et al. (Pediatr Exerc Sci 5:42-50, 1993)(a) that includes triceps skinfold and MS showed the highest d (6.1) but the smallest range (24.1) and slope (0.6). Data from the FITNESSGRAM had the smallest d (1.8 ml kg(-1) min(-1)), but also had the highest range between limits of agreement (28.6 ml kg(-1) min(-1)) and a 1.2 slope. The lowest slope (0.4) and range (22.2 ml kg(-1) min(-1)) were observed using the equation of Fernhall et al. (Am J Ment Retard 102:602-612, 1998). Log transformation of the data revealed that the equations of Matsuzaka et al. (Pediatr Exerc Sci 16:113-125, 2004)(a) (1.1*/÷1.25) and Fernhall et al. (Am J Ment Retard 102:602-612, 1998) (1.17*/÷1.25) showed the closest agreement among all, but they still yield unsatisfactory accuracy.

This study examined whether 20-m shuttle-run performance, sex, body mass index (BMI), age, height, and weight are associated with peak oxygen uptake (VO2peak) in youth with Down syndrome (DS; n = 53; 25 women, age 8-20 years) and whether these variables can be used to develop an equation to predict VO2peak. BMI, 20-m shuttle-run performance, and sex were significantly associated with VO2peak in youth with DS, whereas age, height, and weight were not. A regression model included only shuttle-run performance as a significant predictor of VO2peak; however, the developed prediction equation had low individual predictability. Therefore, 20-m shuttle-run performance alone does not provide valid prediction of VO2peak in youth with DS. Sex, BMI, age, height, and weight do not improve the prediction of VO2peak.

Walking impairment is a ubiquitous feature of multiple sclerosis (MS) and the O(2) cost of walking might quantify this dysfunction in mild MS. This paper examined the difference in O(2) cost of walking between persons with MS who have mild disability and healthy controls and the correlation between the O(2) cost of walking and disability. Study 1 included 18 persons with mild MS and 18 controls and indicated that the O(2) cost of walking was significantly higher in MS than controls and that disability was significantly associated with the O(2) cost of slow, moderate, and fast treadmill walking. Study 2 included 24 persons with mild MS and indicated that disability was significantly correlated with O(2) cost of comfortable, fast, and slow over-ground walking. We provide evidence that the O(2) cost of walking is an indicator of walking dysfunction in mildly disabled persons with MS and should be considered in clinical research and practice.

Aims: We tested the hypothesis that high cardiorespiratory fitness (fitness) is associated with lower levels of arterial stiffness in 1035 (age 52 ± 6 years) men with and without the metabolic syndrome., Methods: Arterial stiffness was derived from brachial-ankle pulse wave velocity (baPWV). Fitness was directly measured by peak oxygen uptake during a standard treadmill test., Results: Men with the metabolic syndrome (n = 168) had significantly higher baPWV than men without the metabolic syndrome (1424 ± 175 cm/s vs. 1333 ± 150 cm/s, p < 0.05). When separated according to quartiles of fitness, men with and without the metabolic syndrome in the highest quartile of fitness had significantly lower baPWV compared to men in the lowest quartile of fitness (p < 0.05). Fitness was inversely correlated with baPWV in men with (p = -0.29, p < 0.05) and without the metabolic syndrome (p = -0.22, p < 0.05). There was no differences in baPWV levels between fit men with the metabolic syndrome and unfit men without the metabolic syndrome (fit/MetS; 1366 ± 140 vs. unfit/no MetS; 1401 ± 194 cm/s, p = 0.81)., Conclusions: These results demonstrate that high fitness is inversely associated with arterial stiffness in men with and without the metabolic syndrome. Increased arterial stiffness in the metabolic syndrome is attenuated by high fitness., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Persons with Down syndrome (DS) have diminished submaximal and peak work capacity. This study evaluated the dynamic response of oxygen uptake at onset and recovery (VO(2) kinetics) of constant-load exercise (moderate intensity 45% VO(2peak)) in adults with DS. A total of 27 healthy participants aged 18-50 years performed graded treadmill exercise to assess peak VO(2): 14 with DS (9 males and 5 females) and 13 controls without disabilities (9 males and 4 females). Subjects also performed constant-load exercise tests at 45% VO(2peak) to determine VO(2) on-transient and VO(2) off-transient responses. Peak VO(2) was lower in participants with DS as compared to controls (DS 30.2 ± 7.1; controls 46.1 ± 9.6 mL kg(-1) min(-1), P < 0.05). In contrast, at 45% VO(2peak), the time constants for the VO(2) on-transients (DS 34.6 ± 9.1; controls 37.6 ± 9.0 s) and VO(2) off-transients (DS 36.5 ± 12.3; controls 37.7 ± 7.0 s) were not significantly different between the groups. Additionally, there were no differences between on-transient and off-transient time constants in participants with DS or controls. These data demonstrate that the VO(2) kinetics at onset and recovery of moderate intensity exercise is similar between adults with DS and controls. Therefore, the submaximal exercise performance of these individuals is not affected by slowed VO(2) kinetics.

Objective: To determine whether the oxygen uptake (VO2) during walking at different speeds in people with multiple sclerosis is underestimated by available prediction equations and whether such underestimation relates to the validity of their assumptions., Design: Cross-sectional comparison., Subjects: Eighteen adults with MS and 18 adults without MS., Methods: VO2 was measured at rest and during treadmill walking at 2.0, 3.0 and 4.0 mph with open-circuit spirometry. The actual VO2 was compared with that estimated by both the American College of Sports Medicine and the van der Walt and Wyndham equations., Results: The differences between the actual VO2 and that estimated by both equations were significantly higher than zero across speeds for both groups (p < 0.001). The underestimation increased with increasing speed (p < 0.001) for both groups and was greater for participants with MS than those without MS (p < 0.011). The inaccurate prediction by the American College of Sports Medicine formula was associated with an underestimation of the net VO2 per meter (p < 0.001), and this was higher for participants with MS (p < 0.007)., Conclusion: Rehabilitation and exercise professionals should recognize that the American College of Sports Medicine and the van der Walt and Wyndham equations underestimate VO2 during treadmill walking in individuals with and without MS.

Background: The 12-item multiple sclerosis walking scale (MSWS-12) has been validated against self-report and clinical markers, but has not been validated with a physiological marker of locomotor impairment., Objective: This study further validates the MSWS-12 based on its correlation with the oxygen cost (O(2) cost) of walking as a physiological marker of locomotor impairment in persons with multiple sclerosis (MS)., Methods: Participants (N=24) with MS completed the MSWS-12 and then wore a portable metabolic unit for measuring the O(2) cost of walking during three 6-min walk (6MW) tests. The first 6MW test involved the participant's comfortable walking speed (CWS), whereas the second and third 6MW tests were undertaken above (faster walking speed, FWS) and below (slower walking speed, SWS) the participant's CWS (i.e., +/-5mph CWS)., Results: MSWS-12 scores correlated strongly with O(2) cost of walking during the 6MW tests undertaken at CWS (r=.641, p=.001), FWS (r=.616, p=.001), and SWS (r=.639, p=.001)., Interpretation: We provide evidence that further confirms the validity of the MSWS-12 as a measure of the impact of MS on walking., (Copyright 2010 Elsevier B.V. All rights reserved.)

Objective: Obesity has been proposed to negatively impact cardiac function in overweight (OW) individuals. The relationship between diastolic dysfunction and oxygen uptake (Vo(2)) kinetics is equivocal. This exploratory investigation evaluated the relationship between resting left ventricular function and Vo(2) kinetics during cycle ergometry in OW and non-overweight (NO) children and adolescents., Research Methods and Procedures: Fourteen OW (>85 percentile for BMI for age and gender) children, 10 boys and 4 girls (age, 11.7 +/- 1.9 years; body mass, 80.6 +/- 45.5 kg) and 10 NO children (4 boys, 6 girls) volunteered to participate in the study (age, 12.5 +/- 2.1 years; body mass, 45.8 +/- 13.8 kg). Resting cardiovascular structure and function were assessed using spectral Doppler echocardiography. All subjects underwent two sub-maximal exercise stages on a cycle ergometer (3 minutes unloaded and 5 minutes at 50 W, both at a cadence of 50 rpm). Respiratory data were measured on a breath-by-breath basis at both workloads and the mean response time (MRT) was calculated., Results: Analysis of the MRT data demonstrated that there were no significant differences between OW and NO (OW, 52.6 +/- 11.7 seconds vs. NO, 45.6 +/- 7.4 seconds). Significant correlations (p < 0.05) were obtained between MRT Vo(2) and echocardiographic-derived mitral valve inflow pressure half-time (r = 0.55) and between MRT Vo(2), and mitral valve inflow deceleration time (r = 0.55)., Discussion: The evidence from this research suggests a possible link between left ventricular diastolic function at rest and oxygen uptake kinetics during sub-maximal exercise in OW and NO children and adolescents.

The purpose of this study was to document the physiological changes that occur in a natural bodybuilder during prolonged contest preparation for a proqualifying contest. During the 26-week preparation, the athlete undertook a calorically restrictive diet with 2 days of elevated carbohydrate intake per week, increased cardiovascular (CV) training, and attempted to maintain resistance-training load. The athlete was weighed twice a week and body composition was measured monthly by DXA. At baseline and every 2 weeks following CV structure and function was measured using a combination of ultrasound, applanation tonometry, and heart rate variability (HRV). Cardiorespiratory performance was measured by VO2peak at baseline, 13 weeks, and 26 weeks. Body weight (88.6 to 73.3 Kg, R² = .99) and percent body fat (17.5 to 7.4%) were reduced during preparation. CV measurements including blood pressure (128/61 to 113/54mmHg), brachial pulse wave velocity (7.9 to 5.8m/s), and measures of wave reflection all improved. Indexed cardiac output was reduced (2.5 to 1.8L/m²) primarily due to a reduction in resting heart rate (71 to 44bpm), and despite an increase in ejection faction (57.9 to 63.9%). Assessment of HRV found a shift in the ratio of low to high frequency (209.2 to 30.9%). Absolute VO2 was minimally reduced despite weight loss resulting in an increase in relative VO2 (41.9 to 47.7ml/Kg). In general, this prolonged contest preparation technique helped the athlete to improve body composition and resulted in positive CV changes, suggesting that this method of contest preparation appears to be effective in natural male bodybuilders. [ABSTRACT FROM AUTHOR]

This study examined whether 20-m shuttle-run performance, sex, body mass index (BMI), age, height, and weight are associated with peak oxygen uptake (VC^peak) in youth with Down syndrome (DS; n = 53; 25 women, age 8-20 years) and whether these variables can be used to develop an equation to predict VO2pcak- BMI, 20-m shuttle-run performance, and sex were significantly associated with VOipeak in youth with DS, whereas age, height, and weight were not. A regression model included only shuttle-run performance as a significant predictor of VO^pcaki however, the developed prediction equation had low individual predictability. Therefore, 20-m shuttle-run performance alone does not provide valid prediction of VC>2peak in youth with DS. Sex, BMI, age, height, and weight do not improve the prediction of VO2peak- [ABSTRACT FROM AUTHOR]

Firefighters’ self-contained breathing apparatus (SCBA) protects the respiratory system during firefighting but increases the physiological burden. Extended duration SCBA (>30 min) have increased air supply, potentially increasing the duration of firefighting work cycles. To examine the effects of SCBA configuration and work cycle (length and rest), 30 firefighters completed seven trials using different SCBA and one or two bouts of simulated firefighting following work cycles common in the United States. Heart rate, core temperature, oxygen consumption, work output and self-reported perceptions were recorded during all activities. Varying SCBA resulted in few differences in these parameters. However, during a second bout, work output significantly declined while heart rates and core temperatures were elevated relative to a single bout. Thirty seven per cent of the subjects were unable to complete the second bout in at least one of the two-bout conditions. These firefighters had lower fitness and higher body mass than those who completed all assigned tasks. Practitioner Summary: The effects of extended duration SCBA and work/rest cycles on physiological parameters and work output have not been examined. Cylinder size had minimal effects, but extended work cycles with no rest resulted in increased physiological strain and decreased work output. This effect was more pronounced in firefighters with lower fitness. [ABSTRACT FROM PUBLISHER]

A standard exercise protocol that allows comparisons across various ergonomic studies would be of great value for researchers investigating the physical and physiological strains of firefighting and possible interventions for reducing the demands. We compared the pattern of cardiorespiratory changes from 21 firefighters during simulated firefighting activities using a newly developed firefighting activity station (FAS) and treadmill walking both performed within an identical laboratory setting. Data on cardiorespiratory parameters and core temperature were collected continuously using a portable metabolic unit and a wireless ingestible temperature probe. Repeated measures ANOVA indicated distinct patterns of change in cardiorespiratory parameters and heart rate between conditions. The pattern consisted of alternating periods of peaks and nadirs in the FAS that were qualitatively and quantitatively similar to live fire activities, whereas the same parameters increased logarithmically in the treadmill condition. Core temperature increased in a similarly for both conditions, although more rapidly in the FAS. Practitioner Summary:The firefighting activity station (FAS) yields a pattern of cardiorespiratory responses qualitatively and quantitatively similar to live fire activities, significantly different than treadmill walking. The FAS can be performed in a laboratory/clinic, providing a potentially standardised protocol for testing interventions to improve health and safety and conducting return to duty decisions. [ABSTRACT FROM PUBLISHER]

Background: The study and application of exercise in multiple sclerosis (MS) often requires cardiopulmonary exercise testing (CPET) to provide a comprehensive assessment of exercise tolerance and responses, including an evaluation of the pulmonary, cardiovascular, and skeletal muscle systems. Research on CPET in persons with MS has considerable limitations, including small sample sizes, often without controls; not reporting outcomes across disability status; and different modalities of exercise testing across studies. Although some key outcome variables of CPET have been studied in persons with MS, additional calculated variables have not been directly studied. Objective: The objective of this study was to provide a comprehensive examination of outcome variables from CPET among persons with MS and healthy controls. Methods: We included data from 162 persons with MS and 80 healthy controls who underwent CPET on a leg ergometer and satisfied criteria for valid testing for measuring oxygen uptake ( VO), carbon dioxide production ( VCO), ventilation (VE), respiratory exchange ratio, work rate, and heart rate (HR). Calculated variables [i.e. ventilatory anaerobic threshold ( VO/ VCO), VE/ VCO slope, VO/power slope, VO/HR slope, and oxygen uptake efficiency slope] were processed using standard guidelines. We examined differences in the CPET variables between groups (e.g. MS vs. controls and categories of mild, moderate, and severe disability status) using analysis of covariance (ANCOVA), controlling for age, sex, body mass index, and disease duration. Results: Overall, persons with MS demonstrate alterations in outcomes from CPET compared with controls, and these are generally exacerbated with increasing disability. Conclusion: Our results provide novel information for the evaluation of CPET in MS for developing exercise prescriptions and documenting adaptations with exercise training based on the comprehensive variables obtained during CPET. [ABSTRACT FROM AUTHOR]

For decades, research to quantify the effects of firefighting activities and personal protective equipment on physiology and biomechanics has been conducted in a variety of testing environments. It is unknown if these different environments provide similar information and comparable responses. A novel Firefighting Activities Station, which simulates four common fireground tasks, is presented for use with an environmental chamber in a controlled laboratory setting. Nineteen firefighters completed three different exercise protocols following common research practices. Simulated firefighting activities conducted in an environmental chamber or live-fire structures elicited similar physiological responses (max heart rate: 190.1 vs 188.0 bpm, core temperature response: 0.047°C/min vs 0.043°C/min) and accelerometry counts. However, the response to a treadmill protocol commonly used in laboratory settings resulted in significantly lower heart rate (178.4 vs 188.0 bpm), core temperature response (0.037°C/min vs 0.043°C/min) and physical activity counts compared with firefighting activities in the burn building. Practitioner Summary: We introduce a new approach for simulating realistic firefighting activities in a controlled laboratory environment for ergonomics assessment of fire service equipment and personnel. Physiological responses to this proposed protocol more closely replicate those from live-fire activities than a traditional treadmill protocol and are simple to replicate and standardise. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the acute effect of cigarette smoking on cardiac autonomic function in young adult smokers during dynamic exercise. Fourteen healthy young smokers (21.4 ± 3.4 years) performed peak and submaximal exercise protocols under control and smoking conditions. Resting and submaximal beat-to-beat R-R series were recorded and spectrally decomposed using the fast Fourier transformation. Smoking resulted in a significant decrease in work time, [Vdot]O2peak and peak O2 pulse (P < 0.05). Heart rate increased at rest and during submaximal exercise after smoking (P < 0.05). The raw high frequency and low frequency power were significantly reduced by smoking, both at rest and during exercise (P < 0.05). The low to high frequency ratio was higher after smoking (P < 0.05). The normalised low frequency power was also significantly increased by smoking, but only at rest (P < 0.05). These data demonstrate that the tachycardic effect elicited by smoking is accompanied by acute changes in heart rate spectral components both at rest and during exercise. Therefore, the cardiac autonomic control is altered by smoking not only at rest, but also during exercise, resulting in reduced vagal modulation and increased sympathetic dominance. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate walking economy in response to steady-state locomotion in adult males with Down syndrome (DS) and in healthy controls. Twelve participants with DS (34.5 +/- 7.0 years) and 11 non-disabled controls (34.3 +/- 8.7 years) performed submaximal (0% grade, 2.5 km h(-1) for 8 min) and maximal treadmill tests with metabolic and heart-rate measurements. For submaximal walking, submaximal oxygen uptake (VO(2)) (9.1 vs. 9.5 mL kg(-1) min(-1)), net VO(2) (5.9 vs. 5.4 mL kg(-1) min(-1)) were not different between the groups (P > 0.05). However, oxygen-pulse (6.6 vs. 8.6 mL/beat) was lower and relative work intensity (44.6 vs. 19.9% of max) was higher in individuals with DS compared to controls (P < 0.05). Findings indicate similar walking economy between groups. Nevertheless, participants with DS exercised at lower submaximal oxygen-pulse and higher percentage of VO(2peak). Therefore, despite similar walking economy, participants with DS have lower cardiorespiratory function than controls for a given steady-state treadmill speed. [ABSTRACT FROM AUTHOR]

Obesity and type 2 diabetes (T2D) are associated with abnormal cardiovascular autonomic function and increased risk for cardiac complications, especially after exercise. Since improvements at rest are not always observed after training, we investigated changes in resting and post-exercise autonomic function in obese women with and without T2D after16-week of walking training. Heart rate (HR) variability (HRV) and baroreflex sensitivity (BRS) were measured at rest and 20 min after a 20 min bout of treadmill exercise at 65% VO(2) peak in obese women with (n = 8) and without T2D (n = 12) before and after training. HRV was analyzed by frequency-domain [high- (HF) power and low-frequency (LF)] and BRS by the sequence method. Exercise training induced similar significant changes in VO(2) peak, resting systolic blood pressure (SBP) and post-exercise autonomic function in both groups. Training increased VO(2 )peak (6%; P < 0.01) and decreased resting SBP (8%; P < 0.001). Increased post-exercise HR recovery (5%; P < 0.001), HF power (14%; P < 0.05), LF power (14%; P < 0.05) and BRS (86%; P < 0.001) were also observed. Resting autonomic function and post-exercise SBP were not altered after training. In conclusion, endurance training reduced blood pressure without changes in HRV and BRS at rest, but training increased HRV and BRS during the recovery of acute endurance exercise indicating an improved post-exercise autonomic modulation of HR, which was similar in obese women with and without T2D. [ABSTRACT FROM AUTHOR]

To determine vasodilatory responsiveness we measured forearm blood flow (FBF) following reactive hyperemia (RH), prior to and following a bout of maximal aerobic exercise in endurance- (n=14) and resistance-trained men (n=10). Both groups were similar in height, body mass, and percentage body fat. Using strain-gauge plethysmography, resting FBF was higher in the resistance-trained group [4.82 (0.84) vs 3.33 (1.17) ml min(-1) 100 ml(-1) of tissue; P<0.05]. However, the resistance-trained group had a 17%-29% lower pre-exercise FBF response to RH for the first 45 s (P<0.05). Following the maximal exercise bout there were no group differences in FBF. Post-exercise FBF was higher compared to pre-exercise values in both the endurance- (P<0.001) and resistance- (P<0.01) trained groups. Endurance-trained men appear to have a greater peak vasodilatory capacity compared to resistance-trained men, and acute maximal exercise increased the vasodilatory capacity in both groups. Acute exercise also equalized the peak vasodilatory response between the endurance- and resistance-trained groups, suggesting the potential for flow-mediated vasodilatation was similar for both groups. [ABSTRACT FROM AUTHOR]

Introduction: Multiple sclerosis (MS) is an immune-mediated, neurological disease that results in physiological deconditioning with increasing disability. High-intensity interval training (HIIT) exercise has induced significant improvements in physiological conditioning in healthy and clinical populations and might be appropriate for persons with MS who have mobility disability. The feasibility and acute effects of HIIT using recumbent stepping in persons with MS who have mobility disability are relatively unknown. Methods: The physiological effects of single sessions of HIIT and continuous (CON), steady-state aerobic exercise using recumbent stepping were compared in 20 persons with MS with mobility disability (i.e., Expanded Disability Status Scale of 4.0–6.5). The HIIT bout included 10 cycles of 1-min intervals at the work rate associated with 90% peak aerobic capacity (V˙O2peak) followed by 1-min recovery intervals at 15 W, totaling 20 min in length. The CON bout consisted of 20 min at the work rate associated with 50% to 60% V˙O2peak. Physiological (i.e., power output, oxygen consumption, carbon dioxide expiration, respiratory exchange ratio, ventilation, HR, and core temperature) and perceptual (i.e., ratings of perceived exertion) measures were collected across the acute sessions. Results: There were statistically significant condition–time interactions for all physiological measures and ratings of perceived exertion expressing differential patterns of change over time for HIIT versus CON (P < 0.05). The main effect of condition was significant for all physiological outcomes, except core temperature, with the HIIT condition inducing significantly higher values than CON (P < 0.05). Conclusions: High-intensity interval training exercise taxes the cardiorespiratory system significantly more than CON, yet without deleterious effects on core temperature in persons with MS. This has important implications for informing an evidence-based exercise prescription that is appropriate for improving physiological conditioning in persons with MS who have mobility disabilities. [ABSTRACT FROM AUTHOR]

Introduction: Individuals with intellectual disabilities (ID) are often sedentary and have low fitness levels. Current knowledge supports the existence of physiological barriers resulting in low fitness and exercise intolerance in individuals with Down syndrome, which might be applicable to other ID etiologies. If physiological barriers exist in ID, this would require adaptation of the physical activity guidelines. Purpose: The aim of this study was to assess differences in cardiopulmonary profiles, including maximal oxygen uptake, during a cardiopulmonary exercise test in individuals with ID without Down syndrome and healthy controls. Methods: Participants performed an incremental cardiopulmonary exercise test on a treadmill until exhaustion. Outcomes were peak heart rate (HRpeak), absolute peak oxygen uptake (V˙O2peak), relative V˙O2peak, peak minute ventilation, peak CO2 expenditure, oxygen uptake efficiency slope, V ˙E/V˙CO2 slope, absolute O2 pulse, relative O2 pulse, difference from predicted HRpeak, HR reserve, RERpeak, ventilatory threshold (VT), and VT as a percentage of V˙O2peak. Differences between groups were analyzed with Student's t -tests and multiple linear regression after adjusting for potential confounders (sex, age, body mass index, and activity level). Results: Individuals with ID had worse outcomes on all of the cardiopulmonary outcomes, except for VT expressed as a percentage of V˙O2peak and V ˙E/V˙CO2 slope (P < 0.05). Having ID was an independent predictor of reduced physiologic function during exercise (P < 0.05). Conclusion: These results demonstrate that individuals with ID present exercise intolerance potentially related to lower HRpeak and impairments in ventilatory function, and these results also suggest the possibility of peripheral muscle hypoperfusion. Existing physical activity guidelines likely underestimate the actual intensity of activity performed by individuals with ID and need to be adapted. [ABSTRACT FROM AUTHOR]

African Americans (AA) have increased carotid artery intima-media thickness and decreased vascular function compared with their Caucasian (CA) peers. Aerobic exercise prevents and potentially reverses arterial dysfunction. Purpose: The purpose of this study was to examine the effect of 8 wk of moderate- to high-intensity aerobic training in young healthy sedentary AA and CA men and women. Methods: Sixty-four healthy volunteers (men, 28; women, 36) with mean age 24 yr underwent measures of arterial structure, function, and blood pressure (BP) variables at baseline, after the 4-wk control period, and 8 wk after training. Results: There was a significant increase in VO2peaj; among both groups after exercise training. Brachial systolic BP decreased significantly after the control period in both groups but not after exercise training. Carotid pulse pressure decreased significantly in both groups after exercise training as compared with that in baseline. There was no change in any of the other BP variables. AA had higher intima-media thickness at baseline and after the control period but it significantly decreased after exercise training compared with that of CA. AA had significantly lower baseline forearm blood flow and reactive hyperemia compared with those of CA, but exercise training had no effect on these variables. There was no significant difference in arterial stiffness (central pulse wave velocity) and wave-reflection (augmentation index) between the two groups at any time point. Conclusions: This is the first study to show that 8 wk of aerobic exercise training causes significant improvement in the arterial structure in young, healthy AA, making it comparable with the CA and with minimal effects on BP variables. [ABSTRACT FROM AUTHOR]

The article presents a study on the relationship between metabolic rate and activity count rate in individuals with and without Down Syndrome (DS). It describes the methodology of the study in which metabolic rate was measured in 18 DS patients using a portable spirometry and a uniaxial accelerometer was used for measuring the activity count rate. The study reveals alterations in metabolic rate and activity count rare during overground walking and lower predictability of metabolic rate in DS patients as compared to individuals without DS.