This study examined longitudinal changes in the pulmonary oxygen uptake (pV̇O2) 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 pV̇O2 at the gas exchange threshold and peak pV̇O2 (Δ). Over the 2-yr period a significant increase in the phase II time constant (25 ± 5 vs. 30 ± 5 s; p = .002, ω2 = 0.34), the relative amplitude of the pV̇O2 slow component (9 ± 5 vs. 13 ± 4%; p = .036, ω2 = 0.14) and the pV̇O2 gain at end-exercise (11.6 ± 0.6 vs. 12.4 ± 0.7 mL·min−1·W−1; p < .001, ω2 = 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.
Breese, Williams, Barker, Welsman, and Armstrong are with the Children’s Health and Exercise Research Center, University of Exeter, Exeter, EX1 2LU, UK. Fawkner is with the School of Life Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, UK.