title: The effect of sustained exercise on follicular phase levels of 17 beta-estradiol in recreational athletes.
abstract: OBJECTIVE
  Our purpose was to test the hypothesis that sustained exercise elevates circulating levels of 17 beta-estradiol in an intensity-dependent manner.
  
  
  METHODS
  Blood samples were obtained in the follicular phase of the menstrual cycle from 75 female recreational athletes before and immediately after 20 minutes of aerobics or running at their usual exercise intensity.
  
  
  RESULTS
  The levels of 17 beta-estradiol rose after exercise 97% of the time. At exercise intensities between 50% and 88% of maximum capacity there was a direct linear relationship (r = 0.57) between exercise intensity and magnitude of increase in estradiol levels. A similar relationship was not present for cortisol.
  
  
  CONCLUSIONS
  Sustained exercise produces an intensity-dependent increase in the levels of 17 beta-estradiol that probably reflects decreased hepatic clearance caused by the fall in splanchnic blood flow. Thus the magnitude of the increase in the level of 17 beta-estradiol can be used as a rough index of the exercise-induced decrease in splanchnic blood flow.
authors.affiliation: Department of Reproductive Biology, Case Western Reserve University, Cleveland, OH.
authors.forename: J F
authors.initials: JF
authors.lastname: Clapp
authors.forename: E L
authors.initials: EL
authors.lastname: Capeless
authors.forename: K D
authors.initials: KD
authors.lastname: Little
mesh_terms: D000328:Adult; D004958:Estradiol / Q000097:blood*; D015444:Exercise; D005260:Female; D005498:Follicular Phase; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D010101:Oxygen Consumption; D011998:Recreation; D013177:Sports; D013997:Time Factors
chemical_list: D004958:Estradiol; D006854:Hydrocortisone