Abstract

Performance and physiologic responses to relative endurance exercise were compared in 21 prepubescent boys (C, mean +/- SD, age = 10.2 +/- 0.28 yrs) and 21 adult men (A, age = 30.0 +/- 1.23 yrs). Relative endurance exercise consisted of pedaling a bicycle ergometer for 8 min at an initial power output of 103 +/- 1.0 VO2 max (mean +/- SE) for the C and 105 +/- 1.1 VO2 max forthe A. Standard open circuit spirometric techniques were used to measure VO2, and HR was monitored via a bipolar ECG. The physiologic (VO2 or HR) responses were graphed and a one-component exponential equation fit to the data. Few differences were evident in power output characteristics (RPM or total dropoff) between C and A. However, many C-A differences were evident in phy- siologic responses. C have a faster VO2 half-time (t 1/2) than that of As (C 17.2 +/- 0.74 s vs A 28.5 +/- 1.31 s). Also, the HR t 1/2 values (C 24.8 +/- 1.96 s vs A 41.0 +/- 2.94 s) indicate that C reached their asymptotic HR more qickly than A. Apparently, young C have quicker VO2 and HR responses to relative endurance exercise. Whether a threshold age exists where the Cs responses mature remains the subject of subsequent investigations. Verf.-Referat