Hormonal secretion during nighttime sleep indicating stress of
daytime exercise.
Kern, Werner, Boris Perras, Reinhard Wodick, Horst L. Fehm, and Jan
Born.
Departments of Internal Medicine and Clinical Neuroendocrinology,
University of Luebeck, 23538 Luebeck, and Department of Physiology,
University of Ulm, 89081 Ulm, Germany
APStracts 2:0297A, 1995.
We tested the hypothesis, that long duration exercise (LDE) of
moderate intensity -but not LDE of low intensity- during the daytime
changes the typical temporal patterns of hormone release during
subsequent nocturnal sleep. Ten trained healthy men participated in a
balanced crossover study including 3 conditions: `no exercise', `LDE
of low intensity' (biking 40 km, 1800-2030 h) and `LDE of moderate
intensity' (biking 120-150 km, 1600-2030 h). During the subsequent
night somnopolygraphic sleep recordings were obtained (2300-0700 h),
and concentrations of cortisol, growth hormone (GH), and testosterone
were measured every 15 min. During the `no exercise' nights the
typical secretory patterns were present with peak concentrations of
GH but nadir concentrations of cortisol during the first half of
sleep, but increased cortisol levels and minimum GH levels during the
second part of sleep. Testosterone concentrations increased during
the second half of sleep. `LDE of moderate intensity' reduced REM
sleep (13.9% versus `no exercise': 16.9%; p<0.01). Levels of
testosterone decreased with increasing intensity of daytime exercise
(p<0.05). Moderate, but not low intensity LDE, decreased GH levels in
the first half (p<0.05) and increased GH levels in the second half
(p<0.005) of sleep. Also, LDE of moderate intensity but not LDE of
low intensity increased cortisol levels during the first half
(p<0.005) and decreased cortisol secretion during the second half
(p<0.05) of sleep. Results suggest that nocturnal profiles of GH and
cortisol concentrations may serve to indicate the disturbance of
normal anabolic functions of sleep due to daytime exercise.
Received 11 January 1994; accepted in final form 20 April 1995.
APS Manuscript Number A37-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.