Is Your Sperm A Couch Potato Too?

A paper published in the February 2013 edition of the British Journal of Sports Medicine reported the not-entirely-surprising conclusion that men who watch more TV tend to have lower sperm counts.

Harvard doctoral student and spokesman for the researchers Audrey Gaskins is quoted by the website Med Page Today as saying that men who watched the least television per week and engaged in the most physical activity had, in the Harvard story, the highest sperm counts, and men who watched the most television and engaged in the least physical activity had the lowest sperm counts.

Male Fertility Has Been a Public Health Concern for Several Decades

The Harvard study of activity and male fertility has been inspired by multiple observations that men's fertility has been on the decline all over the world since 1980, especially in the most advanced, industrialized countries. 

The most alarming studies of male fertility have come from the nation of Denmark, where, for genetic reasons, men tend to have unusually large testicles, and it is apparently relatively easy to recruit men to donate sperm samples for long-term research. (In the most recently published study, men received compensation of approximately €65 for each visit to the clinic.)

A team of researchers at the Rijkshospitalet medical center in Copenhagen collected semen samples from 4,687 men for 15 years, from 1996 to 2010.

Sperm Count Not the Only Problem in Male Fertility

These figures were actually better than averages in sperm samples collected at the hospital during World War II.

Just 23% of men in Denmark, which has some of the highest rates of male fertility in the world, are capable of becoming fathers in a 12-month period, even if their partners have no fertility issues.

Since medical scientists do not yet know how to enhance sperm quality in otherwise healthy men, they have to focus on sperm quantity. The Harvard study suggests that sperm quantity is greatly diminished in men whose lifestyle includes lots of hours in front of the TV, and couch potatoes are considerably less likely to impregnate their partners. The study makes an important point, as society continues to largely focus on women whenever fertility is discussed — but as women start taking folic acid and stop drinking alcohol, it now appears that men who want to become fathers should hit the gym.

Television Not the Only Lifestyle Choice Tied To Lower Male Fertility

Although the recently published Harvard study found that television viewing is highly predictive of problems in male fertility, physical inactivity is hardly the only confounder of men's abilities to become fathers.

Other lifestyle choices that interfere with a man's ability to conceive include:

• Obesity. Fat cells produce an enzyme that converts testosterone, the male sex hormone, to estrogen, the female sex hormone. Loss of testosterone reduces the rate at which new sperm cells are created in the testes, and also reduces sex drive.

• Marijuana use. Smoking pot affects male fertility, but not in the way you might expect. Men who smoke pot regularly may or may not engage in more frequent or more pleasurable sexual intercourse. However, not just the brain but also the sperm respond to the active chemicals in marijuana. In men who have a large percentage of inactive sperm, the sperm tend not to "bind" to the tetrahydrocannabinol (THC) in marijuana, whereas sperm tend to respond to THC in men who have higher counts of viable sperm. If a man's brain cannot respond to pot so he tends to smoke more and more, his sperm usually can't, either.
• Nutritional status. Certain nutrients are associated with higher counts of viable sperm in men 45 years of age and older. Specifically, vitamin C, vitamin E, folic acid, and zinc seem to protect sperm against DNA damage that would incapacitate them from fertilizing the egg.
• Drinking beer. Occasional consumption of beer, up to 1 or 2 beers per day, has little effect on a man's fertility, whatever effect it may have on a man's opportunities to engage in sexual intercourse. Binge drinking, however, damages DNA in sperm. This DNA damage may make sperm completely unviable, or it may create damaged sperm that are capable of fertilizing the egg, but DNA damage in the embryo causes spontaneous abortion or miscarriage.
• Smoking. A study at the University of Heidelberg in Germany found that 18% of men who smoke are infertile.
• Excessive bicycle use. Pressure on the testicles from bike seats is a common, and not always correctable, cause of male infertility.
• Wi-fi. At least one study have found that use of a computer connected to the Internet through a wi-fi connection leads to sperm fragmentation (sperm literally falling apart in semen), lower sperm count, and lower sperm motility. The problem seems to be most acute when a laptop is literally used on the man's lap.
• Steroid use. Use of excessive doses anabolic steroids, especially testosterone, can cause shrinkage of the testes and infertility.

Even greater than these unfortunately lifestyle choices, however, watching too much TV keeps a man from becoming a father. The problem is even worse when excessive TV viewing is combined with the lifestyle choices listed above.

The simplest solution to the problem of lower sperm counts? Spend more time in the boudoir than in the TV room--and don't spend time in front of the television in lieu of exercise or sexual intercourse.