Understanding Anabolic Steroids in Fitness Anabolic steroids are synthetic substances designed to mimic the effects of the male hormone testosterone. In fitness, they are often used to increase muscle mass and improve performance. However, their use is controversial due to the potential for side effects and health risks. This article will explore what anabolic steroids are, how they work, and the pros and cons of using them. What Are Anabolic Steroids?