Influence of exercise intensity and gender on pulmonary O2 uptake (VO2) off‐kinetics in adolescents

Abstract

After exercise, VO2 does not return immediately to its baseline level but it remains elevated to restore metabolic processes to resting condition. The behavior of the off-transient VO2 kinetic response to exercise of various intensities has been well characterized in adult subjects; however, the time profile of the off-transient response has not been studied systematically and characterized in children. The present study investigated the influence of exercise intensity and gender on the off-transient kinetics of pulmonary oxygen uptake in adolescents. Twenty-one (9 males, 12 females) healthy adolescents (14–17 year old) performed square-wave transitions on a cycle ergometer from 20 W to constant work rates of moderate (M), heavy (H), or very heavy (VH) intensity. Mono- and double-exponential models were used to characterize the off-transient kinetic response. A mono-exponential fit provided good characterization of the off-responses at all intensities. The time constant of the fundamental component (τ1) was independent of sex at all intensities averaging M: 55±8 vs. 56±16 s, H: 66±8 vs. 58±5 s, and VH: 72±6 vs. 72±12 s (P > 0.05) in females and males, respectively. The functional gains of the fundamental phase (G= ΔVO2/ΔWR) were not statistically different (P > 0.05) between sexes averaging M: 11.4±0.2, H: 12.4±0.1, and VH: 11.2±0.5 ml·min−1·W−1 in both males and females. Based on our sample size, we conclude that the kinetic response of the fundamental (fast-component) phase of exerciseVO2 recovery in adolescents seems to be independent of the preceding exercise intensity, as well as gender. Supported by NIH, GM-66309-01