The effects of anabolic steroids on rat tendon. An ultrastructural, biomechanical, and biochemical analysis.

Forty-eight male rats were randomly separated into four groups: a control group, a group treated with anabolic steroids, a group treated with daily exercise, and a group treated with both steroids and exercise. At 6 weeks, biomechanical, ultrastructural, and biochemical testing was performed on the Achilles tendons of half of the rats in each group. The remaining rats continued in the experimental protocol, but steroid administration was discontinued. Similar testing was then performed on the remaining rats at 12 weeks. Testing showed anabolic steroids produced a stiffer tendon that absorbs less energy and fails with less elongation; tendon strength was unaffected. Effects were entirely reversible on discontinuation of the steroids. Light microscopic analysis revealed no changes in the appearance of the fibrils. No change in fibril diameter or shape was noted on electron microscopic analysis. Biochemical testing revealed no change in qualitative immunofluorescence staining with Type III collagen or fibronectin. Abuse of anabolic steroids is a widespread problem among competitive athletes; consequently, complications after their use are seen with increasing frequency. Knowledge of the effects of these drugs on tendon and the musculotendinous unit may prove helpful in counseling athletes who use anabolic steroids.