Semen quality is a much-discussed subject among scientists these days. Data suggests sperm concentration has been declining in Western countries over the past couple of decades -- and reasons for the decline are debatable.
The lead author of a new study on the subject, Audrey Gaskins, has been studying the effects of diet and exercise on semen for several years as a doctoral candidate at the Harvard School of Public Health. Her latest research shows a lack of physical activity -- and too much time in front of the television -- may impact sperm count and concentration.
Previous studies have shown a link between physical activity and decreased levels of oxidative stress, Gaskins says. "Oxidative stress" is stress placed on the body as it tries to get rid of free radicals or repair the damage caused by them. Exercise may protect certain male cells from oxidative damage, Gaskins says, leading to increased sperm concentration.
Those findings led Gaskins to complete an observational study on young men's exercise and TV habits as they relate to semen quality. The results were published online Monday in the British Journal of Sports Medicine.
Gaskins and her colleagues asked 189 healthy men between the ages of 18 and 22 how often they exercised each week and how intensely they worked out. The study participants also recorded their TV watching habits.
Then at the clinic, semen samples were collected from each man. The semen was analyzed for sperm size and shape, motility, concentration and total sperm count.
The researchers also conducted a physical examination and looked at the men's diet, body weight, reproductive history, stress levels and smoking habits to rule out other potential causes of their findings.
The men who did moderate to vigorous exercise 15 hours or more per week had a significantly higher sperm concentration than those who worked out less than five hours a week. And the men who watched more than 20 hours of TV a week had almost half the sperm concentration as the men who watched zero hours a week.