The Olympics may be providing a vibrant festival of sport for armchair fans the world over. But for men hoping to become a father at any point in the future, the games could spell problems ahead.
Researchers have found that watching more than five hours of TV a day can slash a man’s sperm count by a third.
Experts at Copenhagen University studied 1,200 healthy young men to see if a couch potato lifestyle affected their fertility.
The results, published in the American Journal of Epidemiology, showed binge-watchers had average sperm counts of 37 million per millilitre of fluid, compared to 52 million per millilitre among men who hardly ever watched TV.
They also had lower levels of the male hormone testosterone, which the body needs to produce sperm. But scientists found spending time sitting at a computer did not appear to have the same adverse effect.
This may be because those who watch too much TV are less likely to be doing much exercise or eating healthily, which are crucial habits for maintaining fertility.
The finding backs up a 2013 US study which found 15 hours of exercise a week could boost sperm quality.
Several studies over the last 20 years have pointed to a worrying decline in men’s sperm count. Some scientists blame high-fat junk food diets, while others say it is caused by traces of the contraceptive pill in drinking water. Another potential suspect is a chemical called BPA used in some plastics.
The latest investigation indicates the biggest factor may simply be men’s laziness and a love of TV. The Danish team screened young men signing up for military service between 2008 and 2012.
Each one was quizzed on their viewing habits and gave a sperm sample for testing.
Sperm counts range from 40 million to 300 million per millilitre of fluid. A low count is judged to be anything below 15 million.
The results showed TV addicts had sperm counts of nearly 30 per cent lower than those who had less sedentary lifestyles.
The findings follow a recent study which revealed watching too much TV raises the risk of dying from a blood clot on the lungs.
For every extra two hours of TV-watching per day, the risk of fatal pulmonary embolism was increased by 40 per cent.
And watching five or more hours made people more than twice as likely to die than those watching less than 2.5 hours. The researchers said in a report on the latest results: ‘Time spent watching television, but not time sitting in front of a computer, was associated with lower sperm counts.
‘Furthermore, decreases in testosterone were detected in men watching many hours of television.’
Nearly half of all UK adults admit to doing no cardio exercise at all, polls suggest, with a further 25 per cent confessing they merely did one hour a week or less.
That means only a mere quarter of grown-ups are running, swimming, going to the gym or playing sport for over an hour each week.
However, there are also risks associated with being more active, as taking part in some sports is said to harm fertility. For instance, too much time riding a bike or running in tight clothing may lower the sperm count.