Forced swimming alters vaginal estrous cycles, body composition, and steroid levels without disrupting lordosis behavior or fertility in rats.
The purpose of the present studies was to examine how exercise affects reproductive physiology and behavior. In four separate experiments, exercise regimens of forced swimming or swimming plus running, were gradually increased in duration to a maximum of 2.5 hours. Vaginal cycles were monitored daily and after eight weeks animals were tested for sexual behavior, ability to breed, changes in body composition, circulating levels of estradiol, progesterone, and corticosterone. Total body lipids were lowered in animals that both ran and swam and parametrial fat pad weight was reduced in all exercising animals. Although exercise lowered circulating levels of ovarian steroids, elevated corticosterone levels and disrupted vaginal cycles, exercised animals exhibited normal sexual behavior and bred successfully. These data indicate that intense exercise can, under certain conditions, disrupt the mechanisms controlling vaginal cycles while the neuroendocrine mechanisms controlling sexual receptivity, ovulation, and fertility remain intact.
Psychology Department, Holy Cross College, Worcester, MA 01610.
J F
JF
Axelson
D000818:Animals; D001823:Body Composition; D003345:Corticosterone / Q000097:blood*; D004958:Estradiol / Q000097:blood*; D004971:Estrus; D005260:Female; D005298:Fertility; D005082:Physical Exertion; D011187:Posture; D011374:Progesterone / Q000097:blood*; D051381:Rats; D012726:Sexual Behavior, Animal; D013550:Swimming; D014621:Vagina / Q000502:physiology*
D011374:Progesterone; D004958:Estradiol; D003345:Corticosterone