title: Effect of endurance exercise on ovulation in the rat.
abstract: This study was designed to evaluate individual variation in ovarian responses to exercise. Rats ran on a treadmill (15% incline) at a rate of 26 m.min-1 for 90 min every day for 14-21 d; control rats were placed on a stationary treadmill for the same period of time. Based on daily vaginal cytology, 9 of 17 exercising rats had abnormal ( > 5 d) estrous cycles in the first cycle of training compared to only 2 of 19 controls. Throughout the training period, the length of estrous cycles of 8 of the 17 exercising rats were relatively unaffected; the mean length of completed cycles was 5.1% +/- 0.4 (SE) d. However, of those length of completed cycles was 5.1 +/- 0>4 (SE) d. However, of those thought to have ovulated based on vaginal cytology, fewer exercising than control rats had new corpora lutea on their ovaries. In exercising rats acyclic periods of up to 21 d were associated with serum progesterone levels similar to those of the diestrus phase of the estrous cycle (mean, 29 +/- 4 SE nmol.l-1). We conclude that treadmill running extends the period of progesterone secretion, delaying ovulation in a susceptible population of rats, and that vaginal cornification may not be an accurate indication of ovulation in these animals.
authors.affiliation: Department of Obstetrics and Gynecology, Northwestern University Medical School School, Chicago, IL 60611, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Chatterton
authors.forename: L
authors.initials: L
authors.lastname: Hrycyk
authors.forename: R C
authors.initials: RC
authors.lastname: Hickson
mesh_terms: D000818:Animals; D004971:Estrus / Q000502:physiology; D005260:Female; D010053:Ovary / Q000473:pathology; D010060:Ovulation / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D011374:Progesterone / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D011374:Progesterone