The oxygen uptake kinetic response to moderate intensity exercise in overweight and non-overweight children (original) (raw)
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2010
This study examined longitudinal changes in the pulmonary oxygen uptake (pVO 2 ) kinetic response to heavy-intensity exercise in 14-16 yr old boys. Fourteen healthy boys (age 14.1 ± 0.2 yr) completed exercise testing on two occasions with a 2-yr interval. Each participant completed a minimum of three 'step' exercise transitions, from unloaded pedalling to a constant work rate corresponding to 40% of the difference between the pVO 2 at the gas exchange threshold and peak pVO 2 (40% Δ). Over the 2-yr period a significant increase in the phase II time constant (25 ± 5 vs. 30 ± 5 s; p = .002, ω 2 = 0.34), the relative amplitude of the pVO 2 slow component (9 ± 5 vs. 13 ± 4%; p = .036, ω 2 = 0.14) and the pVO 2 gain at end-exercise (11.6 ± 0.6 vs. 12.4 ± 0.7 mL·min -1 ·W -1 ; p < .001, ω 2 = 0.42) were observed. These data indicate that the control of oxidative phosphorylation in response to heavy-intensity cycling exercise is age-dependent in teenage boys.
European Journal of Applied Physiology, 2011
The influence of training status on the oxygen uptake ( \( \dot{V}{\text{O}}_{ 2} \) ) response to heavy intensity exercise in pubertal girls has not previously been investigated. We hypothesised that whilst training status-related adaptations would be evident in the \( \dot{V}{\text{O}}_{ 2} \) , heart rate (HR) and deoxyhaemoglobin ([HHb]) kinetics of pubertal swimmers during both lower and upper body exercise, they would be more pronounced during upper body exercise. Eight swim-trained (T; 14.2 ± 0.7 years) and eight untrained (UT; 14.5 ± 1.3 years) girls completed a number of constant-work-rate transitions on cycle and upper body ergometers at 40% of the difference between the gas exchange threshold and peak \( \dot{V}{\text{O}}_{ 2} \) . The phase II \( \dot{V}{\text{O}}_{ 2} \) time constant (τ) was significantly shorter in the trained girls during both cycle (T: 21 ± 6 vs. UT: 35 ± 11 s; P P \( \dot{V}{\text{O}}_{ 2} \) slow component was not influenced by training status. The [HHb] τ was significantly shorter in the trained girls during both cycle (T: 12 ± 2 vs. UT: 20 ± 6 s; P P P \( \dot{V}{\text{O}}_{ 2} \) kinetics in the trained girls and that differences are evident in both lower and upper body exercise.
Pediatric exercise science, 2010
This study examined longitudinal changes in the pulmonary oxygen uptake (pVO(2)) kinetic response to heavy-intensity exercise in 14-16 yr old boys. Fourteen healthy boys (age 14.1 +/- 0.2 yr) completed exercise testing on two occasions with a 2-yr interval. Each participant completed a minimum of three 'step' exercise transitions, from unloaded pedalling to a constant work rate corresponding to 40% of the difference between the pVO(2) at the gas exchange threshold and peak pVO(2) (40% Delta). Over the 2-yr period a significant increase in the phase II time constant (25 +/- 5 vs. 30 +/- 5 s; p = .002, omega(2) = 0.34), the relative amplitude of the pVO(2) slow component (9 +/- 5 vs. 13 +/- 4%; p = .036, omega(2) = 0.14) and the pVO(2) gain at end-exercise (11.6 +/- 0.6 vs. 12.4 +/- 0.7 mL x min(-1) x W(-1); p < .001, omega(2) = 0.42) were observed. These data indicate that the control of oxidative phosphorylation in response to heavy-intensity cycling exercise is age-depen...
Kinetics of oxygen uptake at the onset of exercise in boys and men
Journal of applied physiology (Bethesda, Md. : 1985), 1998
The objective of this study was to compare the O2 uptake (VO2) kinetics at the onset of heavy exercise in boys and men. Nine boys, aged 9-12 yr, and 8 men, aged 19-27 yr, performed a continuous incremental cycling task to determine peak VO2 (VO2 peak). On 2 other days, subjects performed each day four cycling tasks at 80 rpm, each consisting of 2 min of unloaded cycling followed twice by cycling at 50% VO2 peak for 3.5 min, once by cycling at 100% VO2 peak for 2 min, and once by cycling at 130% VO2 peak for 75 s. O2 deficit was not significantly different between boys and men (respectively, 50% VO2 peak task: 6.6 +/- 11.1 vs. 5.5 +/- 7.3 ml . min-1 . kg-1; 100% VO2 peak task: 28.5 +/- 8.1 vs. 31.8 +/- 6.3 ml . min-1 . kg-1; and 130% VO2 peak task: 30.1 +/- 5.7 vs. 35.8 +/- 5.3 ml . min-1 . kg-1). To assess the kinetics, phase I was excluded from analysis. Phase II VO2 kinetics could be described in all cases by a monoexponential function. ANOVA revealed no differences in time consta...
Respiratory physiology & neurobiology, 2012
This study tested the hypothesis that pulmonary VO₂ kinetics would be slowed during 'work-to-work' exercise in adults but not in children. Eight boys (mean age=12.5 ± 0.5 years) and nine men completed very heavy step transitions initiated from either 'unloaded' pedalling (U→VH) or unloaded-to-moderate cycling (i.e. U→M to M→VH). The phase II τ was significantly (p<0.05) lengthened in M→VH compared to U→M and U→VH in boys (30 ± 5 vs. 19 ± 5 vs. 21 ± 5 s) and men (49 ± 14 vs. 30 ± 5 vs. 34 ± 8 s). In U→VH, a greater relative VO₂ slow component temporally coincided with an increased linear iEMG slope in men compared boys (VO₂ slow component: 16 ± 3 vs. 11 ± 4%; iEMG slope: 0.19 ± 0.24 vs. -0.06 ± 0.14%, p<0.05). These results suggest that an age-linked modulation of VO₂ kinetics might be influenced by alterations in muscle fibre recruitment following the onset of exercise.
Oxygen-Uptake Efficiency Slope as a Determinant of Fitness in Overweight Adolescents
Medicine & Science in Sports & Exercise, 2007
Purpose-Peak oxygen uptake (VȮ 2peak ) is frequently difficult to assess in overweight individuals; therefore, submaximal measures that predict VȮ 2peak are proposed as substitutes. Oxygen uptake efficiency slope (OUES) has been suggested as a submaximal measurement of cardiorespiratory fitness that is independent of exercise intensity. There are few data examining its value as a predictor of VȮ 2peak in severely overweight adolescents.
2011
This study tested the hypothesis that pulmonary 2 O V kinetics would be slowed during 'work-to-work' exercise in adults but not in children. Eight boys (mean age = 12.5 ± 0.5 yr) and nine men completed very heavy step transitions initiated from either 'unloaded' pedalling (U→VH) or unloaded-to-moderate cycling (i.e. U→M to M→VH). The phase II τ was significantly (p<0.05) lengthened in M→VH compared to U→M and U→VH in boys (30 ± 5 vs. 19 ± 5 vs. 21 ± 5 s) and men (49 ± 14 vs. 30 ± 5 vs. 34 ± 8 s). In U→VH, a greater relative 2 O V slow component temporally coincided with an increased linear iEMG slope in men compared boys (2 O V slow component: 16 ± 3 vs. 11 ± 4%; iEMG slope: 0.19 ± 0.24 vs.-0.06 ± 0.14%, p<0.05). These results suggest that an agelinked modulation of 2 O V kinetics might be influenced by alterations in muscle fibre recruitment following the onset of exercise.
Clinical Physiology and Functional Imaging, 2007
Aims: Limited research has investigated the most appropriate oxygen uptake ( _ VO 2 ) data averaging method to obtain reliable and valid maximal oxygen uptake ( _ VO 2max ) values. This study investigated the effect of the _ VO 2 time-averaging interval on the reproducibility of _ VO 2max . Methods and results: Twenty-two competitive distance runners (six female) performed two identical incremental treadmill tests to their limit of exercise tolerance separated by at least 48 h. Commencing at 7 km h )1 , running speed was increased by 1 km h )1 per minute for five stages and 0AE5 km h )1 thereafter. Breath-by-breath _ VO 2 data collected during each incremental test were time-averaged over 10-, 15-, 20-, 30-and 60-s and the highest averaged _ VO 2 value was regarded as _ VO 2max for each time-averaging interval. The _ VO 2max values derived from different _ VO 2 timeaveraging intervals were significantly different for the first (F ¼ 39AE6; P<0AE001) and second (F ¼ 68AE9; P<0AE001) incremental test. There was a tendency for _ VO 2max to significantly increase as the time-averaging interval became shorter. The reproducibility of _ VO 2max was similar for all five _ VO 2 time-averages, with no significant differences between the within-subject variance (F ¼ 0AE4; P ¼ 0AE6). Conclusion: The results of this study suggests that the reproducibility of _ VO 2max is not affected by the length of the _ VO 2 time-average interval. However, _ VO 2max was significantly altered by changing the _ VO 2 time-averaging interval between 10 and 60 s. Consistency in the _ VO 2 time-averaging interval is therefore an important methodological consideration for repeated determinations of _ VO 2max .