SCIENTISTS have proven that women who exercise intensively can suffer infertility problems, and new research shows exercise may impair men’s reproductive hormones as well.

A series of new studies suggests that endurance training lowers levels of the major male sex hormone, testosterone, by as much as one third, says Iowa State University exercise physiologist Anthony Hackney.

The changes may be significant enough to alter fertility but more troublesome are the potential long term effects of such hormonal disruptions on athletic boys who still are developing physically.

“What worries me is the adolescent athlete,” says Hackney, an assistant professor of physical education.

A number of studies, including one of 5,000 American women, have documented that regular intensive exercise can disrupt the female menstrual cycle and impair fertility, but little research has been conducted on the effect of activity on male reproductive systems.

Men Hackney studied had been involved in training for more than 10 years, and they exercised an average of six times a week for more than an hour each session.

Because he did not measure sperm counts, Hackney cannot yet say if the changes definitely impair male fertility, although one study several years ago showed that some trained athletes had deficient sperm levels. The levels of testosterone Hackney found in some of his study subjects are low enough to alter sperm count, he says.

His work and that of others who have studied women athletes suggest that the impact of exercise on both sexes is very similar.

Article extracted from this publication >> March 18, 1988