Athletes thrive on testosterone. They use it to build muscle, psychologically prepare themselves for their workouts, and minimize body fat. Athletes who use anabolic steroids sometimes take drugs such as Nolvadex to prevent the conversion of testosterone into estrogen. Many young men take erection-promoting drugs, such as Viagra and Cialis, to help them improve sexual performance.
A study from the University of Rome showed that Cialis not only puts lead in your pencil, but can also increase testosterone levels. Researchers found that fat cells exposed to Cialis converted less testosterone to estrogen. This effect could be responsible for some of the metabolic benefits of Cialis and similar drugs. (Journal Sexual Medicine, published online January 2011)