title: Longitudinal changes in reproductive hormones and menstrual cyclicity in cynomolgus monkeys during strenuous exercise training: abrupt transition to exercise-induced amenorrhea.
abstract: Cross-sectional studies of exercise-induced reproductive dysfunction have documented a high proportion of menstrual cycle disturbances in women involved in strenuous exercise training. However, longitudinal studies have been needed to examine individual susceptibility to exercise-induced reproductive dysfunction and to elucidate the progression of changes in reproductive function that occur with strenuous exercise training. Using the female cynomolgus monkey (Macaca fascicularis), we documented changes in menstrual cyclicity and patterns of LH, FSH, estradiol, and progesterone secretion as the animals developed exercise-induced amenorrhea. As monkeys gradually increased running to 12.3 +/- 0.9 km/day, body weight did not change significantly although food intake remained constant. The time spent training until amenorrhea developed varied widely among animals (7-24 months; mean = 14.3 +/- 2.2 months) and was not correlated with initial body weight, training distance, or food intake. Consistent changes in function of the reproductive axis occurred abruptly, one to two menstrual cycles before the development of amenorrhea. These included significant declines in plasma reproductive hormone concentrations, an increase in follicular phase length, and a decrease in luteal phase progesterone secretion. These data document a high level of interindividual variability in the development of exercise-induced reproductive dysfunction, delineate the progression of changes in reproductive hormone secretion that occur with exercise training, and illustrate an abrupt transition from normal cyclicity to an amenorrheic state in exercising individuals, that is not necessarily associated with weight loss.
authors.affiliation: Department of Psychiatry, University of Pittsburgh, Pennsylvania 15213, USA.
authors.forename: N I
authors.initials: NI
authors.lastname: Williams
authors.forename: A L
authors.initials: AL
authors.lastname: Caston-Balderrama
authors.forename: D L
authors.initials: DL
authors.lastname: Helmreich
authors.forename: D B
authors.initials: DB
authors.lastname: Parfitt
authors.forename: C
authors.initials: C
authors.lastname: Nosbisch
authors.forename: J L
authors.initials: JL
authors.lastname: Cameron
mesh_terms: D000568:Amenorrhea / Q000209:etiology*; D000818:Animals; D004032:Diet; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005498:Follicular Phase; D008137:Longitudinal Studies; D008183:Luteal Phase; D007986:Luteinizing Hormone / Q000097:blood; D008252:Macaca fascicularis; D008597:Menstrual Cycle; D010060:Ovulation; D005082:Physical Exertion; D011374:Progesterone / Q000097:blood; D012098:Reproduction
chemical_list: D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone