Longitudinal changes in the oxygen uptake kinetic response to heavy-intensity exercise in 14- to 16-year-old boys

This study examined longitudinal changes in the pulmonary oxygen uptake (pVO2) 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 pVO2 at the gas exchange threshold and peak pVO2(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 pVO2slow component (9 ± 5 vs. 13 ± 4%; p = .036, ω2 = 0.14) and the pVO2 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.}