The purpose was to examine selected physiological responses of endurance-trained male wheelchair athletes in different Paralympic racing classes (T2, n = 3; T3, n = 8; T4, n = 7) during a 10-km treadmill time trial (TM:10-km). Peak oxygen uptake (V̇O2 peak) was determined, and a TM:10-km was completed on a motorized treadmill. From this, % V̇O2peak utilized and the relationship between V̇O2peak and TM:10-km were established. During the TM:10-km, the following dependent variables were examined: propulsion speed, oxygen uptake, respiratory exchange ratio, and heart rate. The results showed athletes utilize a high % V̇O2peak (78.4 –13.6%) during the TM:10-km. There was a moderate correlation (r = -.57, p < .01) between VO2peak and TM:10-km. No physiological differences were found between the paraplegic racing classes (T3, T4), which suggests that there is some justification in amalgamating these racing classes for endurance events.
Ian G. Campbell, Clyde Williams and Henryk K.A. Lakomy
Monique Mendelson, Anne-Sophie Michallet, Julia Tonini, Anne Favre-Juvin, Michel Guinot, Bernard Wuyam and Patrice Flore
To examine the role of ventilatory constraint on cardiorespiratory fitness in obese adolescents.
Thirty obese adolescents performed a maximal incremental cycling exercise and were divided into 2 groups based on maximal oxygen uptake (VO2peak): those presenting low (L; n = 15; VO2peak: 72.9 ± 8.6% predicted) or normal (N; n = 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.
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.
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.
Saul R. Bloxham, Joanne R. Welsman and Neil Armstrong
This study examined ergometer-specific relationships between short-term power and peak oxygen uptake (peak VO2) in children. Boys (n = 28) and girls (n = 28) age 11-12 years completed two incremental tests to exhaustion on a cycle ergometer and motorized treadmill for the determination of peak VO2. In addition, they completed two 30 s “all-out” sprint tests, one on a cycle ergometer and one on a nonmotorized treadmill for the assessment of peak power (PP) and mean power (MP). Relationships between peak VO2 and shortterm power measures were examined by sex for cycle- and treadmill-derived data using simple per-body-mass ratios and sample-specific allometric exponents to control for body size differences. From correlational analyses on scaled data, sex differences in responses were shown. In boys, PP and MP were unrelated to peak VO2 for cycle-derived measures but significantly related (r = 0.58 PP; r = 0.69 MP) for treadmill values. PP and MP were significantly related to peak VO2 for both modes of exercise in girls (r = .41−.68). In all but one case, correlation coefficients based on mass-related data were higher than those based on allometrically adjusted data.
Danette M. Rogers, Kenneth R. Turley, Kathleen I. Kujawa, Kevin M. Harper and Jack H. Wilmore
This study was designed to examine the relationship between oxygen consumption and both body surface area and body mass in children to determine what allometric scaling factors from these variables provide appropriate means of expressing data for this population. These scaling factors were then compared to exponents based on theoretical and animal models to determine if the same relationships were present. Forty-two children (21 boys and 21 girls) 7 to 9 years of age participated in maximal and submaximal treadmill testing. The submaximal V̇O2 to body size relationship proved to be a more appropriate factor to use when scaling V̇O2 than the relationship seen between body size and V̇O2max. Therefore, in this population of children, V̇O2 relative to body surface area or body mass to the power 0.67, demonstrated submaximally, provided a more appropriate means of data expression both statistically and physiologically than the traditional expression of V̇O2 relative to body mass (ml·kg−1·min−1).
Amanda J. Visek, Erin A. Olson and Loretta DiPietro
Little is known about factors affecting adherence to highly-structured and supervised exercise programs in older people.
Healthy, inactive older (≥65 y) women (N = 30) were randomized into a 1) higher- (ATH—80% VO2peak); 2) moderate- (ATM—65% VO2peak) intensity aerobic; or 3) lower-intensity resistance (RTL; 50% VO2peak) group. All 3 groups exercised 4 days·week-1 for an average of 45 to 70 min·session-1 over 9 months. Adherence (%) was defined as the proportion of prescribed sessions (N = 144) in which subjects achieved their 1) prescribed heart rate (intensity adherence) and 2) their prescribed duration (duration adherence). Primary determinants of adherence included prescribed intensity (METs) and prescribed duration (min), as well as age, body composition, VO2peak, and exercise self-efficacy score.
Intensity adherence was nearly 100% for all 3 groups, while duration adherence was 95%, 91%, and 85% in the RTL, ATH, and ATM groups, respectively. Prescribed exercise duration was the strongest determinant of duration adherence (r = −0.72; P < .0001), independent of prescribed METs, age, VO2peak, and body composition.
Due to competing lifestyle demands, exercise intensity may be less of a factor in adherence among older women than is exercise duration.
Bo Fernhall and Garth T. Tymeson
This study evaluated the concurrent validity of the 300-yard and the 1.5-mile run with a group of mildly mentally retarded (MR) adults. The subjects, 15 healthy MR adults (M age = 29.5 + 5.6 yrs, M IQ = 60), underwent a maximal treadmill test utilizing a walking protocol, with heart rate and oxygen consumption data collected every minute. They also completed a 300-yard and a 1.5-mile run. The order of testing was counterbalanced. The results indicated that these subjects exhibited very poor cardiovascular fitness levels, with a mean V̇O2max of 28.1 ml•kg-1•min-1 and mean run times of 98.9 sec and 21.1 min for the 300-yard and the 1.5-mile runs, respectively. The correlation between V̇O2max and the 1.5-mile run was –.88, and the correlation for the 300-yard run and V̇O2max was –.71. However, partial correlations indicated that when the effect of height and weight were held constant, only the correlation between V̇O2max and the 1.5-mile run remained significant whereas that between V̇O2max and the 300-yard run dropped. Consequently, the 1.5-mile run appears to be a valid indicator of cardiovascular fitness for these adults with MR, but the 300 yard run is not.
Thomas Losnegard, Martin Andersen, Matt Spencer and Jostein Hallén
To investigate the effects of an active and a passive recovery protocol on physiological responses and performance between 2 heats in sprint cross-country skiing.
Ten elite male skiers (22 ± 3 y, 184 ± 4 cm, 79 ± 7 kg) undertook 2 experimental test sessions that both consisted of 2 heats with 25 min between start of the first and second heats. The heats were conducted as an 800-m time trial (6°, >3.5 m/s, ~205 s) and included measurements of oxygen uptake (VO2) and accumulated oxygen deficit. The active recovery trial involved 2 min standing/walking, 16 min jogging (58% ± 5% of VO2peak), and 3 min standing/walking. The passive recovery trial involved 15 min sitting, 3 min walk/jog (~ 30% of VO2peak), and 3 min standing/walking. Blood lactate concentration and heart rate were monitored throughout the recovery periods.
The increased 800-m time between heat 1 and heat 2 was trivial after active recovery (effect size [ES] = 0.1, P = .64) and small after passive recovery (ES = 0.4, P = .14). The 1.2% ± 2.1% (mean ± 90% CL) difference between protocols was not significant (ES = 0.3, P = .3). In heat 2, peak and average VO2 was increased after the active recovery protocol.
Neither passive recovery nor running at ~58% of VO2peak between 2 heats changed performance significantly.
Andrew M. Murray, Joong Hyun Ryu, John Sproule, Anthony P. Turner, Phil Graham-Smith and Marco Cardinale
Running performance is influenced by the interaction of biomechanical and physiological factors. Miniaturized accelerometers worn by athletes can be used to quantify mechanical aspects of running and as a noninvasive tool to assess training status and progression. The aim of this study was to define and validate a method to assess running regularity and allow the estimation of an individual’s oxygen uptake (V̇O2) and/or blood lactate—[La]b—based on data collected with accelerometers and heart rate.
Male adolescent endurance athletes completed an incremental submaximal aerobic stage test where V̇O2 and [La]b were measured. The test was terminated when [La]b concentration at the end of the stage exceeded 4 mmol/L. Two wireless triaxial accelerometers were placed on participants’ right shank and lower back throughout the test. The root mean square (RMS) and sample entropy (SampEn) were calculated for the vertical, mediolateral, and anteroposterior components of acceleration.
There were significant positive correlations of acceleration and entropy variables with [La]b and V̇O2, with moderate to high coefficients (r = .43–.87). RMS of the shank acceleration was the most highly related with both physiological variables. When the accelerometer was attached on the trunk, SampEn of the vertical acceleration had the strongest relationship with V̇O2 (r = .76, P < .01).
The described method analyzing running complexity may allow an assessment of gait variability, which noninvasively tracks V̇O2 and/or [La]b, allowing monitoring of fatigue or training readiness for trained adolescent individuals.
Renee E. Magnan, Bethany M. Kwan, Joseph T. Ciccolo, Burke Gurney, Christine M. Mermier and Angela D. Bryan
Maximal oxygen uptake (VO2max), an assessment of cardiorespiratory fitness, is regularly used as the primary outcome in exercise interventions. Many criteria have been suggested for validating such tests—most commonly, a plateau in oxygen consumption. The current study investigated the proportion of inactive individuals who reached a plateau in oxygen uptake and who achieved a valid test as assessed by secondary criteria (RERmax ≥ 1.1; RPEmax ≥ 18; age predicted HRmax ±10bpm), and the correlates of a successful plateau or achievement of secondary criteria during a VO2max session.
Participants (n = 240) were inactive individuals who completed VO2max assessments using an incremental treadmill test. We explored physical, behavioral, and motivational factors as predictors of meeting criteria for meeting a valid test.
Approximately 59% of the sample achieved plateau using absolute (increase of VO2 of 150ml O2 or less) and 37% achieved plateau using relative (increase of VO2 of 1.5ml/kg O2 or less) criteria. Being male, having a higher BMI, a greater waist-to-hip ratio, and increased self-efficacy were associated with lower odds of achieving an absolute plateau, whereas none of these factors predicted odds of achieving relative plateau.
Findings raise questions about the validity of commonly used criteria with less active populations.
Kenneth H. Pitetti, Bo Fernhall, Nancy Stubbs and Louis V. Stadler Jr.
The purpose of this study was to determine if a step test could be feasible, reliable, and valid for youths with educable (EMR) or trainable (TMR) mental retardation. Thirteen males and 11 females (age M = 14.7 ± 2.7 yr) with EMR or TMR participated in this study. Three step tests were employed using one platform height and stepping frequencies of 13, 15, and 17 ascents/min for 3 min. Recovery HR was used to estimate VO2peak. Though significant, correlations between the recovery HR and VO2peak for the 15 (r = −0.48) and 17 (r = −0.46) ascents/min were not high enough to be considered valid indicators of VO2peak. The large standard errors of the estimate and total errors suggested systematic errors of prediction. Furthermore, the measured VO2peak was significantly different from the estimated values at all step rates (p < .05). The step-test was relatively feasible, but was not a valid test of VO2peak in this population.