Attainment of maximal exercise criteria in boys and men

摘要

Background. This study tested the hypothesis that the occurrence of a VO_2 plateau at maximal exercise would be greater in men versus boys. Secondary indicators of maximal effort also were examined. Methods. Sixteen boys (10.7+-0.6 yrs) and 21 men (22.5+-2.0 yrs) performed a graded exercise test on a treadmill at a constant speed of 8.04 km·hr~(-1) with 2.5% increments in elevation. The men also performed a second test at 11.26 km·hr~(-1) with similar increases in slope. Results. At 8.04 km·hr~(-1), VO_2max was 52.3+-6.0 and 52.5+-5.1 ml·kg~(-1)·min~(-1) in boys and men, respectively (p>0.05). In the men, VO_2max (53.3+-5.4 ml·kg~(-1)·min~(-1)) was higher (p<0.05) in the faster protocol. The percentage of men achieving the criterion was nearly double the percentage of boys (23.8 vs 12.5%), although the difference was not significant. Age-specific criteria heart rate (HR) and respiratory exchange ratio (RER) were achieved in a similar manner; however, more men (100%) than boys (86.7%) achieved an age-specific blood lac-tate (BLa) criterion (p<0.05). Plateau achievement increased to 33.0% in the 11.26 km·hr~(-1) protocol, but was not significantly different from 8.04 km·hr~(-1). HR, RER and BLa criteria achievement were comparable. Conclusions. Maturation may influence the achievement of a plateau and BLa criteria, but not age-specific criteria for RER or HR.