Clasey, J. L., Weltman, J. Y., Nass, R., Pezzoli, S. S., Weltman, A., Thorner, M. O., & Hartman, M. L. (1998). Effect of a single bout of exercise on 4-hr and 24-hr growth hormone (GH) release in young and older subjects. Medicine and Science in Sports and Exercise, 30(5), Supplement abstract 602.

Changes in growth hormone (GH) and cortisol after heavy resistance training were observed in young adults (M = 4; F = 5) and older adults (M = 5; F = 5). Serum GH was measured every 10 minutes for 24 hours after completion of exercise. Both groups of Ss were assessed post-exercise and after non-exercise.

It was found that:

• increases in GH were similar after 4 hours and independent of age;
• after 24 hours GH was similar between the exercise and no-exercise conditions; and
• after 24 hours, GH was lower for the older Ss than the younger Ss.

Implication. The effects of exercise on GH secretion last for at least 4 hours but are dissipated within 24 hours.

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