title: Effect of fatiguing bicycle exercise on thyroid hormone and testosterone levels in sedentary males supplemented with oral zinc.
abstract: OBJECTIVE
  The aim of this study was to determine how exercise affects thyroid hormones and testosterone levels in sedentary men receiving oral zinc for 4 weeks.
  
  
  METHODS
  The study included 10 volunteers (mean age, 19.47+/-1.7 years) who did not exercise. All subjects received supplements of oral zinc sulfate (3 mg/kg/day) for 4 weeks and their normal diets. The thyroid hormone and testosterone levels of all subjects were determined at rest and after bicycle exercise before and after zinc supplementation.
  
  
  RESULTS
  TT3, TT4, FT3, and total and free testosterone levels decreased after exercise compared to resting levels before supplementation (p<0.01). Both the resting and fatigue hormone values were higher after 4 weeks of supplementation than the resting and fatigue values before supplementation (p<0.05).
  
  
  CONCLUSIONS
  The results indicate that exercise decreases thyroid hormones and testosterone in sedentary men; however, zinc supplementation prevents this decrease. Administration of a physiologic dose of zinc can be beneficial to performance.
authors.affiliation: School of Physical Education and Sports, Selcuk University, Konya, Turkey. kmkilic@yahoo.com.tr
authors.forename: Mehmet
authors.initials: M
authors.lastname: Kilic
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D019587:Dietary Supplements; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D005221:Fatigue / Q000097:blood*; D006801:Humans; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D013739:Testosterone / Q000097:blood*; D013963:Thyroid Hormones / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014131:Trace Elements / Q000008:administration & dosage; D014284:Triiodothyronine / Q000097:blood; D015032:Zinc / Q000008:administration & dosage / Q000502:physiology*
chemical_list: D013963:Thyroid Hormones; D014131:Trace Elements; D014284:Triiodothyronine; D013739:Testosterone; D015032:Zinc; D013974:Thyroxine