Anabolic steroids therapy in athletes increases the production of a nitrogenous compound called Creatine Phosphate (CP). CP promotes the storage of certain enzymes in a muscle cell including ATP (Adenosine Triphosphate). ATP is used by the body for muscle contractions. This enzyme breaks down to ADP (Adenosine Diphosphate) which is the fuel used to make muscles move. As more Creatine Phosphate is available, the conversion of ATP to ADP is enhanced meaning that strength will increase. Incidentally, this is the effect that is thought to be facilitated through creatine monohydrate supplementation -- making this a supplement of significant interest as of late. Oxandrolone, an oral anabolic steroid, is thought to significantly increase CP production by the muscle. This is likely the reason many athletes find Anavar to increase strength even when mass may not increase (60).
Anabolic steroids lead to an increase in the body’s actual blood volume. Two to three weeks into a steroid cycle, blood volume increases by 10% to 20%. Athletes who have used steroids, refer to this as the "steroid pump" or a condition that develops during resistance training whereby, a muscle develops a much larger, more vascular appearance. This "steroid pump" is actually a side effect of the increase in blood volume specifically the red blood cells -- the oxygen carrying component of blood. The increase leads to greater blood flow to the working muscles during training periods. Besides the obvious desirable appearance of an enlarged muscle, the muscle becomes stronger as well. Obviously, this increases training intensity and is a stimulus for new growth. The second benefit to athletes relates to oxygen efficiency with increased RBC (red blood cell) volume. This reported increase in blood volume is the major benefit of steroids to endurance athletes. After the steroid therapy is discontinued, extra plasma volume returns to the normal level, leaving behind an increased RBC count. This increased hemoglobin concentration can increase maximum aerobic capacity. A similar beneficial effect can be achieved through a process known as blood doping. Blood doping involves the reinfusion of blood into an athlete prior to athletic competition. An athletes blood is removed, cooled to increase oxagenation, and then injected back into the athlete (6).