Exercise Might Boost Men's Sperm Counts
Meanwhile, other research saw no fertility effects from caffeine, alcohol
By Dennis Thompson
MONDAY, Oct. 14 (HealthDay News) -- Exercise may boost a man's sperm count, and therefore may improve a couple's chances of conception, according to a new study.
In particular, men who lift weights or spend time working or exercising outdoors tended to have a higher-than-average sperm concentration in their semen, said study co-author Audrey Gaskins, a doctoral student at the Harvard School of Public Health.
"Men engaging in exercise for seven hours or more per week, essentially one hour a day, had 48 percent higher concentrations than men who were engaging in less than one hour per week," Gaskins said.
The study will be presented this week at the joint meeting of the International Federation of Fertility Societies and the American Society for Reproductive Medicine, held in Boston.
Meanwhile, two other studies being released at the meeting found that neither coffee nor alcohol affects a man's ability to conceive, contradicting concerns raised by earlier research.
"Even though caffeine and alcohol are generally considered a risk factor for decreased fertility, we saw no evidence of that," said co-author Dr. Jorge Chavarro, an assistant professor of nutrition and epidemiology at the Harvard School of Public Health.
The exercise study focused on the male partners of couples who sought treatment at the Massachusetts General Hospital Fertility Center between 2006 and 2012. Ultimately, 137 men provided semen samples and filled out questionnaires regarding their regular levels of physical activity.
"When we looked overall, we found that men who engaged in levels of moderate to vigorous activity had higher levels of sperm concentration," Gaskins said.
Further, the researchers found that particular types of pursuits boosted sperm counts more than others. "Outdoor activities and weightlifting seemed to be driving the association between moderate to vigorous activity and sperm concentration," Gaskins said.
Men who spent more than an hour and a half each week engaging in physical activity outdoors had a 42 percent higher sperm concentration than those who spent no time outdoors, she said.
Weightlifters who spent two or more hours a week pumping iron had a 25 percent increase in sperm count compared to men who did not lift weights.
"Weightlifting has been shown to increase testosterone levels and improve insulin sensitivity," Gaskins said. "Both of those have been related to higher sperm concentrations."
Gaskins speculated that outdoor exposure to sunlight might boost fertility by increasing men's levels of vitamin D.
The researchers found that one form of outdoor exercise actually can decrease male fertility, however. Men who rode a bicycle for more than an hour and a half each week had 34 percent lower sperm concentrations than men who did not bike.
Pressure placed against the scrotum by a bike seat or the increased scrotal temperatures caused by such pressure are possible explanations for this decrease in fertility, Gaskins said.