Longitudinal Changes in the Oxygen Uptake Kinetic Response to Heavy-Intensity Exercise in 14- to 16-Year-Old Boys

<jats:p>This study examined longitudinal changes in the pulmonary oxygen uptake (<jats:italic>pV̇O</jats:italic><jats:sub>2</jats:sub>) 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 <jats:italic>pV̇O</jats:italic><jats:sub>2</jats:sub> at the gas exchange threshold and peak <jats:italic>pV̇O</jats:italic><jats:sub>2</jats:sub> (40% Δ). Over the 2-yr period a significant increase in the phase II time constant (25 ± 5 vs. 30 ± 5 s; <jats:italic>p</jats:italic> = .002, ω<jats:sup>2</jats:sup> = 0.34), the relative amplitude of the <jats:italic>pV̇O</jats:italic><jats:sub>2</jats:sub> slow component (9 ± 5 vs. 13 ± 4%; <jats:italic>p</jats:italic> = .036, ω<jats:sup>2</jats:sup> = 0.14) and the <jats:italic>pV̇O</jats:italic><jats:sub>2</jats:sub> gain at end-exercise (11.6 ± 0.6 vs. 12.4 ± 0.7 mL·min<jats:sup>−1</jats:sup>·W<jats:sup>−1</jats:sup>; <jats:italic>p</jats:italic> &lt; .001, ω<jats:sup>2</jats:sup> = 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.</jats:p>