Neary J. P. Ph.D.; Wheeler, G. D. Ph.D.; Maclean, I. M.Sc.; Cumming, D. C. M.B.Ch.B.; Quinney, H. A. Ph.D.Clinical Journal of Sport Medicine: July 1994 Editorial: PDF Only Free Abstract Abstract: To examine the effects of endurance cycle training on urinary free cortisol (C) and serum testosterone (T), 27 male club-level cyclists [mean of the sample maximum oxygen consumption (XVo2max) = 3.95 ± 0.30 L/min] progressively trained to an intensity of 85% Vo2max for 60 min/session four times weekly for 7 weeks. Venous blood and a 24-h urine sample were collected each week and analyzed for hemoglobin (Hb), hematocrit (Hct), serum T, and urinary C. With training, Vo2max was significantly increased (p < 0.05) to 4.42 ± 0.30 L/min without significant changes from initial Hb (15.6 g/dl) or Hct (46%). Mean serum T levels were initially at the low end of the normal range (11.3 ± 0.67 nM) and did not change significantly with training (10.0 ± 0.88 nM). Urinary C levels were significantly (p < 0.05) greater than values in eight sedentary control subjects (74.8 ± 10.4 nmol/day) and increased further with training from 111.4 ± 8.6 to 210.5 ± 15.9 nmol/day. The T/C ratio was significantly decreased from 10.2 (10-2) to 4.8 (10-2) by the end of training. These results suggest that strenuous endurance cycle training alters the ratio of anabolic to catabolic hormones. With further investigation, urinary C may become a useful indicator of exercise training stress. © Lippincott-Raven Publishers.