TRT and Injury: Does One Lead to Another? – Pharma / TRT – COMMUNITY

Why are men reporting tendon injuries after getting on TRT? Isn’t testosterone supposed to make the body more resilient? Answers here.

Anabolic steroid users have long suspected a link between tendon injuries and steroid use. There are two general theories as to how this could occur:

Theory 1: Steroids cause the muscles to get bigger and stronger while the tendons comparatively remain the same, leading to eventual injury.

Theory 2: High doses combined with heavy lifting cause direct weakening or stiffening of the tendons, leading to injury.

However, researchers are unable to form any firm conclusions about testosterone and tendon injuries after a comprehensive review of the scientific literature (1).

This is where the plot thickens. Recent retrospective case-control studies reveal significantly higher odds of tendon injuries in those taking exogenous testosterone versus those who are not. Men taking testosterone were nearly five times more likely to suffer a distal biceps tendon injury within one year of initiating therapy (2).

Researchers found similar results when evaluating the odds of quad tendon injury. The ratio of injury was nearly six times greater in those taking testosterone (3).

Weird, right? You probably wouldn’t expect these results among doctor-prescribed TRT users if most steroid users weren’t reporting the same tendon problems.

Not so fast. There are reasons not to draw such a firm conclusion. Aside from more obvious limitations, like this type of study design doesn’t allow causation to be established, it’s important to note potential confounders. A confounder is a variable that may affect the outcome (tendon health) and has a relationship to the potential cause, like testosterone use in this case.

First, even though these studies also included women, the odds ratios for tendon injury were either indistinguishable between those taking testosterone and those not taking testosterone, or they were only slightly elevated in an older age group. (However, this wasn’t consistent and well within the range to be explained by several forms of research bias (4).)

If we aren’t seeing this across both sexes, it indicates a more complicated picture than simply testosterone equaling greater odds of tendon injury.

One weakness of these studies where researchers found an association (in men) between testosterone administration and tendon injury was the lack of consideration for concomitant medication use. In layman’s terms, that’s the use of other meds simultaneously.

Using aromatase inhibitors (AIs), despite being prudent and necessary for some, can also cause harmful changes to the integrity of tendons, making the users more prone to injury (5, 6). For those new to this topic, aromatase inhibitors prevent testosterone from converting to estrogen.

While probably underreported, AIs alone are known to cause tendon injuries. More recent in vitro research suggests testosterone and estrogen have an almost yin-and-yang relationship regarding tendon integrity and function (6). When estrogen isn’t present in sufficient concentrations, tendons may become more prone to injury.

This might also explain the association between anabolic steroid use and tendon injuries in those cases where endogenous testosterone is suppressed and no exogenous source of testosterone is present.

It also explains why women generally had no association between tendon injury and testosterone administration. They have much higher estrogen levels than men and rarely receive AIs as part of any TRT program. These medications are typically reserved for breast cancer treatment.

The evidence for TRT causing tendon injury isn’t as strong as some research has shown. I’d bet the association is due to AI use. If your clinician is administering an AI as part of your TRT, be sure he’s monitoring your estrogen levels and report any joint pain to him.