Background Cross-sectional studies examining training effects on development of performance variables have been confounded by growth and development changes. In order to examine the relative contribution of training, there was a need to collect ‘growth’ data longitudinally.

Aims and objectives The purpose of this study was to examine age- and maturity-associated variation in longitudinal physiological characteristics development in elite and non-elite adolescent males.

Methods Longitudinal measures of peak VO₂, submaximal VO₂, and power output in 11 elite, (13.7–17.8 years), and five non-elite males (13.1–17.6 years), over 2 or 3 consecutive years were examined. Maturity was assessed using Tanner’s (1962) indices of secondary sexual characteristics.

Results Sum of skinfolds remained the same in the elite group yet increased in the non-elite. Peak VO₂ was greater in the elite males by 9.1 ml/kg/min, with no change in age. Oxygen uptake at 10.6 km/h declined by 1.2 ml/kg/min per year in each group. Percentage peak VO₂ at the same running speed was l2% lower in the elite and declined by 1.3% each year in both groups. Blood lactate concentration was 1.5 mmol/l lower in the elite males compared to the non-elite, however there was no decline with age. Peak and mean power output increased disproportionately in the elite group, with percentage fatigue increasing similarly.

Conclusion Body fatness increases across adolescence in the untrained male. Peak VO₂ remains stable throughout adolescence but is characteristically higher in elites either as a result of strenuous training or genetic endowment. Running economy improves with age in both elite and non-elite but does not appear to be related to training status. Short-term power output shows a disproportionate increase with age in the elite male athlete compared to the untrained contemporary, which may have been influenced by differences in body composition between groups.