PROSPECTIVE EVALUATION OF RISK-FACTORS FOR EXERCISE-INDUCED HYPOGONADISM IN MALE RUNNERS

Exercise-induced hypogonadotropic hypogonadism is well recognized amon g female endurance athletes but is less commonly observed in male endu rance athletes. We have reported a well-characterized case of severe a cquired hypogonadotropic hypogonadism in a male distance runner with o steopenia, stress fracture, and sexual dysfunction. Using this case as an index, we hypothesized that the presence of 1 or more specific ris k factors would prospectively identify male endurance athletes with ex ercise-induced hypogonadotropic hypogonadism, These include a history of stress fracture, sexual dysfunction, or the initiation of endurance exercise before age 18 years. We studied 28 male endurance runners yo unger than 50 years who ran more than 40 miles per week. Of these runn ers, 15 had 1 or more of the above risk factors (group 1), and the rem aining 13 had none of the putative risk factors (group 2). A group of 10 sedentary control subjects was also studied (group 3). There was no difference between groups 1 and 2 in weekly training mileage. Group 1 was younger than group 2 (32+/-10 years versus 39+/-6 years, P<.05) a nd had a lower body mass index (22.4+/-1.9 kg per m(2) versus 23.9+/-2 .2 kg per m2, P<.05). By bioelectric impedance, preliminary data showe d that group 1 had a reduced body fat content (group 1, 14.5%+/-2.8%; group 2, 16.9%+/-2.0%; and group 3, 17.5%+/-4.1%; P<.05). Fasting morn ing concentrations of free testosterone (group 1, 45.3 +/- 26.4 pmol/l ; group 2, 88.8 +/- 24.3 pmol/l; and group 3, 69.1 +/-21.5 pmol/l) and luteinizing hormone (group 1, 1.7+/-0.7 IU per liter; group 2, 2.0+/- 1.1 IU per liter; and group 3, 1.9+/-0.6 IU per liter) did not differ among the groups (P>.05). One subject with primary hypogonadism was id entified in group 1. The presence of the aforementioned risk factors d oes not predict the occurrence of exercise-induced hypogonadotropic hy pogonadism among male endurance runners in this pilot study. A larger sample size or more discriminating risk factors (or both) may be neces sary to identify this uncommon but potentially debilitating condition.