Even healthy men could improve their sperm quality by spending less time in front of the tube.
Studies show that the quality of sperm, measured in concentration of sperm and sperm count, is declining in Western countries, with some suggesting a drop of up to 38% in concentration. Numerous factors could explain the trend, from lower levels of physical activity to exposure to environmental chemicals. But the downward dip in sperm quality matches up with increased TV viewing, so researchers from the Harvard School of Public Health (HSPH) decided to investigate the relationship between TV viewing, physical activity and semen quality.
The scientists analyzed the semen quality of 189 relatively healthy New York men aged 18 to 22, who were asked about how often and how intensely they exercised, as well as the amount of time they spent watching TV, videos or DVDs. The men were all normal weight and height, and the majority did not smoke.
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Reporting in the British Journal of Sports Medicine the researchers found that on average, the men spent from five to 14 hours exercising and four to 20 hours a week in front of the TV.
Men who spent 20 or more hours a week in front of the TV had a sperm count that was on average 44% lower than that of men who spent less time watching TV. And those who were the most physically active also enjoyed a 73% higher sperm count than those who were more sedentary. Being more active and watching less TV were associated with a higher sperm count and sperm concentration for the young men overall.
The connection between TV viewing and sperm count could be a marker for other factors that distinguish those who spend more time in front of the screen than those who don’t. For example, the TV watchers are likely to be more sedentary, and therefore have less healthy diets than those who spend less time in front of the TV. Those who don’t watch hours of television are also more likely to be physically active, and regular exercise has been linked to healthy sperm counts in previous studies.
And then there is the physical explanation for why spending too much time on the couch can lower sperm counts: it’s possible that increased scrotal temperatures from remaining in the sitting position too long can contribute to poorer-quality sperm.
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Lower sperm counts don’t necessarily mean a man is less fertile, but staying active may help to keep sperm healthy. “We know very little about how lifestyle may impact semen quality and male fertility in general, so identifying two potentially modifiable factors that appear to have such a big impact on sperm counts is truly exciting,” says study author Audrey Gaskins of HSPH Department of Nutrition.