Testosterone is an androgenic and anabolic steroid secreted by the testes in men. Women also secrete some through the ovaries, and some is also produced by the adrenal glands. Testosterone is primarily a male hormone, and thus men produce about 40 to 60 percent more than women. The anabolic effects of steroids are associated with muscle development and lean body mass. In sports and bodybuilding, anabolic steroid use is common, in an effort to increase muscle mass and strength.
Muscle Protein Synthesis
Bodybuilders often attempt to increase muscle mass beyond what the normal human body is capable of. The development of muscle in your body is somewhat limited due to a combination of your unique genetic disposition and the demands you put on your body. You can change the demands you put on your body by participating in a weight-training program, but there is a wall that you cannot pass genetically, unless you increase the testosterone in your body. The term "anabolic" refers to a building up of organs or tissues in the body. According to Steroid.com, by increasing "free" testosterone in the body with the use of anabolic steroids, bodybuilders increase muscle protein production, and by doing so increase the amount of muscle in their bodies beyond their genetic limitations.
Cortisol
Cortisol is a hormone that breaks muscle tissue down. As new muscle tissue is produced, old tissue is cannibalized. According to Bodybuilding.com, cortisol is categorized as catabolic, as it has the opposite effect as testosterone, insulin and growth hormone in that it breaks down tissue rather than building it up. The use of testosterone has been associated with limiting this process, by preventing cortisol from tearing down muscle tissue as effectively. This results in more muscle mass over time, and this is another perceived benefit to bodybuilders.
Red Blood Cells
Red blood cells transport oxygen to working muscles, removing lactic acid buildup as you exercise. The ability to overload the muscle is necessary in order to cause your body to rebuild and form new muscle tissue. If you can improve your training by increasing how hard you can push yourself, then you will end up with more overload, and thus more muscle tissue. According to an article in "Bio-Medicine" entitled, "Testosterone Replacement Improves Muscle Strength, Function in HIV-Infected Women," from 2006, a group of women taking testosterone supplementation showed significant improvements in muscle strength and function compared with measurements taken before the study. It is believed that testosterone increases red blood cell concentration, allowing you to push yourself harder in your workouts, thus resulting in greater improvements in muscle mass over time.
References
- BioMedicine: Testosterone replacement improves muscle strength, function in HIV-infected women
- MayoClinic.com: Testosterone therapy: Key to male vitality?
- JCEM Endo Journals: Testosterone Replacement Increases Fat-Free Mass and Muscle Size in Hypogonadal Men
- BodyBuilding.com: The Implications of Cortisol Release
