Guys, anybody need a boost off the couch in the wake of the Super Bowl? Here you go: A new study from researchers at the Harvard School of Public Health suggests that turning off your TV and getting back into playing sports rather than just watching them could be good for your sperm quality.
The study, just out online in the British Journal of Sports Medicine, surveyed 189 college-age men at the University of Rochester about their exercise and TV habits, along with health-related questions about diet, smoking and stress. It also analyzed their semen quality.
Lead author Audrey Gaskins, a Harvard doctoral student, sums up the results: “Men who were in the top category of physical activity, which translated into 15 hours or more per week, had 73 percent higher sperm counts than those who exercised for less than five hours a week.”
“Then we looked at TV-watching and found that the men who watched the most TV — more than 20 hours per week — had 44% lower sperm counts compared to men who watched almost no TV. Our results show that modifiable lifestyle factors — physical activity and TV watching — could have a big impact on sperm count.”
Research over the last several years has suggested that semen quality has been declining in most Western countries. Gaskins says the new study's motivation was to determine whether sedentary lifestyles might explain that decline. It controlled for several other factors that might have been at work, including stress levels, smoking and diet.
The findings sketched out "a linear trend" among the men, she said; the more they exercised, and the less television they watched, the higher the quality of their sperm tended to be.
Interestingly, the results did not echo previous studies that found a drop-off in sperm quality among elite athletes, particularly cyclists. "There is some evidence to suggest that different types of activities affect sperm quality differently," she said.
What might cause sperm quality differences between sportsmen and couch potatoes? One hypothesis, Gaskins said, is that physical activity reduces oxidative stress levels that can lower sperm counts.
"In terms of TV-watching," she said, "ours is the first study to look at this and find significant results. Comparable studies on sedentary behavior have asked how many hours you sit at work, the main hypothesis being that when men are in a sitting position, it makes the scrotal environment too warm for appropriate spermatogenesis. So that's one hypothesis but not everyone fully believes that. There could be other factors at play."
Take-home message? "We found that two potentially modifiable lifestyle factors — physical activity and TV watching — could have a big impact on sperm count. So it's definitely something to consider if you're having trouble conceiving or even thinking about it."
From the Harvard School of Public Health press release:
Mild exercise did not affect sperm quality.
“The majority of the previous studies on physical activity and semen quality had focused on professional marathon runners and cyclists, who reach physical activity levels that most people in the world cannot match. We were able to examine a range of physical activity that is more relevant to men in the general population,” said Jorge Chavarro, senior author of the study and assistant professor of nutrition and epidemiology at HSPH.
The authors caution that, while a reduced sperm count has been linked to lower fertility, it does not necessarily preclude men from fathering a child.
My idle thought: So might there be an evolutionary reason why jocks reign in high school? Does their physical prowess send a message of high potency to potential mates? Readers, thoughts?
This program aired on February 4, 2013. The audio for this program is not available.