Oxygen uptake during running as related to body mass in circumpubertal boys: a longitudinal study

SummaryTo investigate the effect of endurance training on physiological characteristics during circumpubertal growth, eight young runners (mean starting age 12 years) were studied every 6 months for 8 years. Four other boys served as untrained controls. Oxygen uptake ( $$\dot V$$ O2) and blood lactate concentrations were measured during submaximal and maximal treadmill running. The data were aligned with each individual's age of peak height velocity. The maximal oxygen uptake ( $$\dot V$$ O2max; ml · kg−1 · min−1) decreased with growth in the untrained group but remained almost constant in the training group. The oxygen cost of running at 15 km · h−1 ( $$\dot V$$ O215, ml · kg−1 · min−1) was persistently lower in the trained group but decreased similarly with age in both groups. The development of $$\dot V$$ O2max and $$\dot V$$ O215 (1 · min−1) was related to each individual's increase in body mass so that power functions were obtained. The mean body mass scaling factor was 0.78 (SEM 0.07) and 1.01 (SEM 0.04) for $$\dot V$$ O2max and 0.75 (SEM 0.09) and 0.75 (SEM 0.02) for $$\dot V$$ O215 in the untrained and trained groups, respectively. Therefore, expressed as ml · kg−0.75 · min−1, $$\dot V$$ O215 was unchanged in both groups and $$\dot V$$ O2max increased only in the trained group. The running velocity corresponding to 4 mmol · 1−1 of blood lactate (νla4) increased only in the trained group. Blood lactate concentration at exhaustion remained constant in both groups over the years studied. In conclusion, recent and the present findings would suggest that changes in the oxygen cost of running and $$\dot V$$ O2max (ml · kg−1 · min−1) during growth may mainly be due to an overestimation of the body mass dependency of $$\dot V$$ O02 during running. The $$\dot V$$ O2 determined during treadmill running may be better related to kg0.75 than to kg1.