February 5, 2013

expert reaction to new research into physical activity, TV watching and semen quality

A study in the British Journal of Sports Medicine found young men who watch TV for more than 20 hours a week have almost half the sperm count of men who watch very little TV, while men who do 15 or more hours of moderate to vigorous exercise every week have sperm counts that are 73% higher than those who exercise very little. A before the headlines analysis accompanied this roundup.

Dr Allan Pacey, Senior Lecturer in Andrology, University of Sheffield, said:

“This is an interesting paper which examines the role of sedentary lifestyle on male fertility by looking at semen quality in men who are physically active versus those who are not. The results are intriguing and suggest that men who do regular exercise have higher sperm counts than men who watch a lot of television.

“On the face of it, this seems like a well conducted study albeit with a relatively small number of participants. Having said that the authors appear to have used good methodology and have attempted to control for all of the obvious variables that might differ between the two groups of men (e.g. diet, smoking, BMI etc). Their conclusions are plausible, and I would agree that there is evidence to suggest that moderate exercise could change men’s physiology sufficiently to improve testicular health. Similarly, we already know that testicular heating through sedentary jobs or tight underwear can decrease sperm counts and so arguably the same effect might be seen in men who spend too many hours on the sofa watching television.

“However, it remains to be seen if coaxing a TV watching couch potato into doing some regular exercise could actually improve his sperm count. Or whether there exists an unknown fundamental difference between men who like exercise and those who do not which might account for the findings. This should be a relatively easy study to perform, but before all worried men hunt for their sports bag it’s important to note that other research suggests that doing too much exercise can be harmful to sperm production and this study did not examine the type and intensity of exercise their participants were undertaking.

“My advice would be everything in moderation – and that includes time in the gym as well as watching TV (or perhaps both at the same time!)”

‘Physical activity and television watching in relation to semen quality in young men’ by Gaskins et al., published in British Journal of Sports Medicine  on Monday 4 February 2013.