Journal of Applied Physiology, Vol 63, Issue 3 1165-1173, Copyright © 1987 by American Physiological Society
Effect of exercise on the onset of puberty, gonadotropins, and ovarian inhibin
J. Pellerin-Massicotte, G. R. Brisson, C. St-Pierre, P. Rioux and D. Rajotte
Departement des Sciences Pures, Universite du Quebec a Rimouski, Canada.
Swimming 6 h/day from 11 days of age led to a significant delay of the
onset of puberty of female rats compared with the sedentary group. Rats who
were in contact with water but without the energy expenditure due to
exercise (paddlers) had their vaginal opening in a middle point between
control and exercising rats. Vaginal opening occurred at different ages but
at a same body weight. Exercise and stress led to a marked decrease of the
body weights between 19 and 40 days of age. Serum luteinizing hormone and
follicle-stimulating hormone were increased with the exercise program at 30
days of age, whereas no significant differences between groups in serum
gonadotropins were observed at 50 days of age. Only the anterior pituitary
luteinizing hormone content was increased by exercise in adult rats. Total
ovarian proteins were significantly reduced by stress and to a greater
degree by exercise. Ovarian inhibin activity is not modified by exercise at
30 days of age, whereas it increased significantly in the exercising group
at 50 days of age and to a lesser degree in paddlers. It is therefore
suggested that the onset of puberty in rats is dependent on a critical
weight and that exercise and stress can delay the onset of puberty. This
delay could be explained by a deficiency of hormonal maturational process
while exercising until sexual maturity alters the inhibin activity, which
suggests that inhibin could play a major role for the normal reproductive
function and this could possibly explain the menstrual disturbances in the
female athlete.
