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Int J Sports Med 1981; 02(4): 240-244
DOI: 10.1055/s-2008-1034617
© Georg Thieme Verlag Stuttgart · New York

Transient Oxygen Uptake and Heart Rate Responses at the Onset of Relative Endurance Exercise in Prepubertal Boys and Adult Men*

S. P. Sady
  • School of Health, Physical Education and Recreation, The University of Nebraska at Omaha, Omaha, Nebraska 68182, USA
* This research was conducted at the Physical Performance Research Laboratory of the Department of Physical Education. The University of Michigan.
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Publication History

Publication Date:
14 March 2008 (online)

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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% V̇O2max (mean ± SE) for the C and 105 ± 1.1% V̇O2max for the A (P > 0.05). Standard open circuit Spirometrie techniques were used to measure V̇O2, and HR was monitored via a bipolar ECG. The physiologic (V̇O2 or HR) responses were graphed and a one-component exponential equation fit to the data. Few differences (P > 0.05) were evident in power output characteristics (RPM or total% dropoff) between C and A. However, many C-A differences were evident in physiologic responses. C have a faster V̇O2 half-time (t1/2) than that of As (C 17.2 ± 0.74 s vs A 28.5 ± 1.31 s, P < 0.05). Also, the HR 11/2 values (C 24.8 ± 1.96 s vs A 41.0 ± 2.94 s, P < 0.05) indicate that C reached their asymptotic HR more quickly than A. Apparently, young C have quicker V̇O2 and HR responses to relative endurance exercise. Whether a threshold age exists where the Cs responses “mature” remains the subject of subsequent investigations.

Key words

relative endurance - supramaximal - heart rate - oxygen consumption - kinetics

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