Moderate Exercise: Good for You and Good for Your Sperm

Male infertility is a significant problem in the U.S. According to the Centers for Disease Control and Prevention, 4.7 million men are affected by it and 40 percent of couples attempting conception fail because of it.

Genital defects, sperm transportation issues (motility), erection and ejaculatory failure, low sperm production or function issues, complications from surgery, and exposure to toxic agents are all factors that cause male infertility.

Fortunately about 70 percent of the problem is treatable through medical intervention and non-surgical options, but in about 25 percent of the cases, infertility could have been avoided with greater awareness of the lifestyle choices that can harm sperm.

One of those life style choices is exercise. However, not all exercise is created equal. A new study reveals a possible connection between moderate amounts of exercise and sperm motility (the sperms' ability to swim toward an egg). Researchers from Kuramoto Women's Clinic and the Department of Urology at Yamaguchi University in Japan presented their findings in October 2011 at the annual meeting of the American Society for Reproductive Medicine. They reported that men who don't exercise too strenuously have better sperm motility than those who over do it. Moderate exercisers are also better off than sedentary men.

In the study, 215 men attending an IVF clinic from April 2010 to April 2011 provided semen samples and information about their physical activity levels. The men who were divided into three groups—strenuous, moderate, and light exercisers—provided at least two semen samples. The semen was evaluated for volume, sperm concentration, and sperm motility. Age and body mass index were similar among the three groups of men.

The moderate-exercise group had the highest average sperm motility and the fewest men with less than 40 percent sperm motility (14.3 percent), while 31 percent of those in the light-exercise group and 27 percent of those in the strenuous-exercise group had less than 40 percent sperm motility.

"Exercise is a component of an overall healthy lifestyle which contributes to reproductive health," said Dolores Lamb, PhD, President-elect of ASRM in a press release. "This study which uses frequency, intensity, and duration to quantify the amount of exercise a subject gets, shows that a moderate exercise routine may be recommended to modestly improve semen parameters in men with no known conditions that impair their reproductive capacity,"

Strenuous exercise has been examined in other infertility studies. Men who run more than 100 miles a week have lower sperm counts and testosterone levels. Another recent study out of Boston University found that too much bike riding is also associated with male infertility. According to that study, men who ride more than five hours a week are twice as likely to have a low sperm count and impaired sperm motility. Trauma from the bike seat along with temperature increases in the scrotum during bike riding may explain the relationship between biking and semen health.

Experts recommend that male cyclists who are trying to conceive ride no more than 30 miles at a time—mainly to limit their time wearing tight bicycle shorts. Using a seat with a wide back—rather than a hard, narrow one is also recommended.




American Urological Association

American Society for Reproductive Medicine

National Institutes of Health

The Centers for Disease Control and Prevention