Recovery O2 and blood lactic acid: longitudinal analysis in boys aged 11 to 15 years.

Nineteen boys were tested annually from age 11 to 15 years. Recovery O2 (or O2 debt in l and ml X kg-1) and blood lactate ([La], mmol X l-1) were measured following supramaximal treadmill tests (20% grade) designed to stress the anaerobic energy systems maximally. The purpose was to describe the rate of development of anaerobic capacity (AnC) from pre-puberty to adolescence. AnC improved from age 11 to 15 years, as indicated by a tripling of recovery O2 (l), 80% increase in recovery O2 per kg and 45% in [La]. Changes were similar from year to year with average yearly increments in recovery O2 of 0.8 l or 9 ml X kg-1 and in [La] of 0.9 mmol X l-1. Individual data also were plotted in relation to age of peak height velocity (PHV, 12.9 +/- 1.2 years). Changes in the measures of AnC were not significantly different when related to biological rather than chronological age. Development of AnC did not show a growth function curve and was not closely correlated with size, nor was the development of AnC enhanced immediately following maturation. Thus, in this longitudinal study, recovery O2 and [La] as measures of AnC showed large increases from age 11 to 15 years, but the gains were similar year to year rather than related to size growth, per se, or hormonal influences at maturation postulated to induce qualitative changes in glycolytic potential of muscle.