Does testosterone make better athletes?

Testosterone has been in the news a lot these days. It’s always being marketed on the radio by “doctors” as a cure-all for aging, it’s pretty much required to take if you’re a Nike-sponsored track athlete or a Tour de France podium finisher, and now it’s even being used to determine the not-at-all dichotomous question of sex and gender.

Currently, the IAAF, or track & field’s international governing body, determines if a female can compete based on how much testosterone she has in her blood. This is a bad idea, both from a women’s equality perspective and a biological perspective.

Testosterone supplementation is also the most popular way for athletes to gain a competitive edge, from MMA fighters to distance runners. But it may not really make that much of a difference in terms of athletic performance (placebo effect, anyone?).

That’s because testosterone, the mayor of hormoneville and the most controversial of the four-ring steroid hormones, is a complicated little molecule.

There’s active and inactive forms, epi- forms and normal forms (epitestosterone is like pre-testosterone, for storage), and the delicate balance between testosterone, androgens, estrogens, and corticoids.


Look at this diagram. What a mess! And this is the high school chemistry version, not the upper division biochemistry diagram complete with hundreds of arrows, pathways, and enzymes.

That’s testosterone in the bottom left. Taking a testosterone injection will obviously increase testosterone, but it’s also going to mess with every other four-ring structure in this picture. That’s why you really shouldn’t take testosterone supplements in middle age to treat the medically ambiguous but excessively advertised “Low T” syndrome.

Our hormonal systems are incredibly dynamic. All those pathways in the diagram go whichever way the wind blows, physiologically speaking. They change from day to day, even minute to minute. Testosterone can spike to crazy high levels before a competition, sink to untraceable levels during competition, then land somewhere in between during recovery.

That makes testing difficult. There’s no standard level of testosterone in humans. Doping tests are sensitive to big spikes that are way outside of physiological ranges, but what’s high for one athlete may be low for another.

Many athletes, especially the endurance variety, are known to have lower than average resting “T” levels. We’re not sure why, but it probably has something to do with that diagram shifting more to the catabolic, or tissue breakdown side due to large amounts of training.

And there are some women that have naturally higher levels of testosterone. Does that make them better athletes? We have no idea. Thankfully the IAAF has been told to re-evaluate their testosterone love affair.

The biological passport is an attractive but still imperfect way of keeping an eye on testosterone.

So why do athletes take it then? There is clear evidence that testosterone supplementation builds strength and muscle mass over the long term in normal healthy men. But there’s absolutely zero evidence that taking testosterone on Friday will help during Saturday’s big race. Testosterone, and all steroid hormones, take many days to rebuild tissues.

And athletic performance is about more than muscles and hormones. According to Dr. Shalender Bhasin, chief of endocrinology, diabetes and nutrition at Boston Medical Center and author of the seminal study above, “the explanations of cause and effect between athletic performance and testosterone are very weak.”

The evidence just doesn’t add up.

Maybe coaches, athletes, and sports czars know more than the world’s finest hormone scientists, or maybe it’s all speculation and locker room talk. Either way, they’re not really helping their sports.

Photo credit: selligpau/wikimedia commons