Which of the following is a common physical effect of steroid use?

Increased muscle mass is a well-documented effect of steroid use, particularly anabolic steroids. These substances promote protein synthesis within cells, leading to an increase in muscle size and strength. Steroids enhance the body's ability to recover from workouts, allowing for more intense training and faster gains in muscle mass. This interaction with the body's hormonal systems primarily targets the testosterone pathways, which are critical for muscle development.

In contrast, options related to decreased or stable muscle mass are not characteristic outcomes of steroid use. Steroid users typically seek to enhance their physical performance and appearance, and the primary effect is indeed the increase in muscle mass, making this choice accurate in the context of anabolic steroids' effects.