Newsflash: Exercise Is Good For You

A recent study in the journal Steroids has offered yet another reason to head outside and leave the couch behind. Researchers subjected mice to thirty minutes of treadmill running and then took samples of muscle tissue for analysis. They found that concentrations of the steroid hormones testosterone, DHT (dihydrotestosterone), and DHEA (dehydroepiandrosterone) were increased (compared to baseline) after exercise as well as expression of the enzyme 5alpha-reductase. In women, expression of the androgen receptor also increased.

Testosterone is usually thought of as the chemical basis of virility and the hormonal source of "male-ness". Though there's some truth to that claim, the reality is that masculinity is much more complex than a single chemical running through the blood. In fact, women have appreciable levels of testosterone, and those levels are responsible for regulating processes as disparate as libido, bone density, and muscle growth. Importantly, increased testosterone in muscle tissue is associated with strength and muscle increases.

The most important result of the study, though, may be the sex difference in expression of the androgen receptor. Testosterone, being a hormone, must bind to the androgen receptor to exert biological effects. Increased expression of the androgen receptor consequently results in more of the testosterone signal being propagated, which means stronger muscles and, likely, strong bones.

In short, yet more validation of a well-known fact -- that exercise makes you strong and healthy -- with a twist: the benefits for women may be even more substantial than those for men.