Reproductive hormone responses to resistance exercise.

To investigate if changes in circulating testosterone levels during isokinetic resistance exercise in women were similar to those during intense aerobic exercise and to examine concomitant changes in hemoconcentration, specific binding protein (sex hormone binding globulin-binding capacity), non-sex hormone binding globulin bound testosterone, luteinizing hormone, follicle-stimulating hormone, cortisol, and lactate, blood samples were obtained through an indwelling cannula at 30 and 15 min before exercise, after each of six exercises on upper and lower body muscle groups, and at 15 and 30 min after exercise in seven normal menstruating women. Investigations lasting approximately 60 min were performed in the early follicular phase beginning at 3.30 p.m. after two months of training with isokinetic ("Nautilus") equipment. Baseline testosterone and non-sex hormone binding globulin bound testosterone levels were significantly higher in subjects than in a control group. Increased total and non-sex hormone binding globulin bound testosterone was observed immediately prior to exercise with further increases late in exercise, then with proportional increases in cortisol and lactic acid. Sex hormone binding globulin-binding capacity increased before exercise. The testosterone increments exceeded hemoconcentration. Luteinizing hormone and follicle-stimulating hormone levels increased during exercise. The data suggest that origins of the exercise-associated testosterone increment are complex, resulting from hemoconcentration and specific gonadal and adrenal responses.