title: Effects of intensified training and detraining on testicular function.
abstract: OBJECTIVE
  To examine the effects of an increased training load and period of detraining on testicular function in male distance runners.
  
  
  METHODS
  Multiple-group time-series design using a control group.
  
  
  METHODS
  University of Toledo and Toledo Hospital.
  
  
  METHODS
  Eight male runners and eight age-matched sedentary control subjects. Subjects were considered fit for participation after a physical and genital examination conducted by a physician.
  
  
  METHODS
  Subjects provided blood and semen samples every 2 weeks for 8 weeks. The training regimen for the runners consisted of 2 weeks at normal training (NT), 2 weeks at 143% of NT (IT1), 2 weeks at 186% of NT (IT2), and 2 weeks at 50% of NT (RT). These percentages represent increases in training distance (volume).
  
  
  METHODS
  Within the context of this investigation, the following hypothesis was developed: increases or decreases in training would not significantly alter sperm count, density, motility, or morphology, or concentrations of reproductive hormones or cortisol in runners.
  
  
  RESULTS
  There were no statistically significant differences observed between runners and control subjects for any of the reproductive hormones or cortisol. In addition, there was no significant treatment effect for sperm count, motility, or morphology. The sperm levels in two runners in this investigation dropped to oligospermatic levels after IT2; however, total sperm count increased in both runners after 2 weeks of RT.
  
  
  CONCLUSIONS
  Four weeks of increased training and 2 weeks of reduced training did not significantly affect the subjects in this investigation. It is possible that a particular level or degree of training must be surpassed before any clinical alterations are evident. Future longitudinal studies are necessary to identify the extent to which endurance training may alter reproductive hormones and testicular function.
authors.affiliation: University of Toledo, Ohio, USA.
authors.forename: H L
authors.initials: HL
authors.lastname: Hall
authors.forename: M G
authors.initials: MG
authors.lastname: Flynn
authors.forename: K K
authors.initials: KK
authors.lastname: Carroll
authors.forename: P G
authors.initials: PG
authors.lastname: Brolinson
authors.forename: S
authors.initials: S
authors.lastname: Shapiro
authors.forename: B A
authors.initials: BA
authors.lastname: Bushman
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D010907:Pituitary Hormones / Q000032:analysis; D012420:Running / Q000502:physiology*; D012661:Semen; D013076:Sperm Count; D013737:Testis / Q000502:physiology*; D013739:Testosterone / Q000032:analysis
chemical_list: D010907:Pituitary Hormones; D013739:Testosterone