title: Testosterone, cortisol, and creatine kinase levels in male distance runners during reduced training.
abstract: The purpose of this study was to examine if reduced training would reestablish normal testosterone, cortisol, and creatine kinase (CK) levels in male distance runners. Ten male runners (mean +/- SE) age 32.0 +/- 2.6 yrs, body fat 9.6 +/- 1.0%, VO2max 61.8 +/- 1.1 ml/kg/min) were monitored during 4 weeks of normal training (baseline training, BT) and 3 weeks of reduced training (RT). During BT running distance averaged 81 +/- 5 km/week, 6 days/week. During RT the runners reduced weekly training volume by 70% of BT to 24 +/- 2 km/week and training frequency to 5 days/week. Weekly resting blood samples were obtained between 0600-0900 hrs after an overnight fast. During BT resting total testosterone levels averaged 5.10 +/- 0.21 ng/ml, which is within the low ranges previously reported in male distance runners. Testosterone levels were not affected by RT (avg of 5.38 +/- 0.31 ng/ml). Cortisol levels were in the high range of normal during BT (23.61 +/- 1.18 ug/dl) and were not altered with RT (avg of 23.14 +/- 1.56 ug/dl). Creatine kinase was elevated (168 +/- 15 U/L) during BT and was significantly reduced (P less than 0.001) at weeks 1-3 of RT (avg of 99 +/- 9 U/L). These results suggest that normally training male runners have low resting total testosterone levels and cortisol levels in the high-normal range. Resting testosterone and cortisol were not responsive to the training reduction. Creatine kinase appears to be sensitive to relative changes in training.
authors.affiliation: Human Performance Laboratory, Ball State University, Muncie, IN 47306.
authors.forename: J A
authors.initials: JA
authors.lastname: Houmard
authors.forename: D L
authors.initials: DL
authors.lastname: Costill
authors.forename: J B
authors.initials: JB
authors.lastname: Mitchell
authors.forename: S H
authors.initials: SH
authors.lastname: Park
authors.forename: W J
authors.initials: WJ
authors.lastname: Fink
authors.forename: J M
authors.initials: JM
authors.lastname: Burns
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000223:Adaptation, Psychological / Q000502:physiology; D000328:Adult; D003402:Creatine Kinase / Q000097:blood*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D010806:Physical Education and Training / Q000379:methods*; D010807:Physical Endurance / Q000502:physiology*; D012420:Running; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D003402:Creatine Kinase; D006854:Hydrocortisone