For years scientific consensus was that using anabolic steroids would decrease the number of androgen receptors. That’s a problem because testosterone must interact with cellular androgen receptors to activate anabolic processes in cells. The less receptor activity, the less testosterone-cellular activity.
Scientists surmised that using large doses of anabolic steroids would eventually result in a downregulation of androgen receptors, rendering the steroids useless. Later studies, however, proved that hypothesis to be incorrect. In fact, steroids provided an opposite effect: They opened up additional androgen receptors.
That led to the now accepted dose-response relationship of steroids: Larger doses of steroids provide more anabolic effects than lower doses. In fact, the initial studies that used low doses of steroids did see a drop in androgen receptor activity, since androgen receptors are saturated by normal blood testosterone. Those findings explain why athletes use such comparatively large doses of various anabolic steroids. It works.
What about the testosterone that the body naturally makes? Various studies show that all things being equal, having naturally higher testosterone predisposes a trainee to making faster gains in muscle size and strength. There’s some controversy, however, about the effects of exercise on testosterone release. Some studies show that exercise results in higher counts of testosterone, while others show little or no effect. Still other studies show that intense training paradoxically lowers androgen-receptor density. So the question is, Can lifting weights both increase testosterone and maintain androgen receptor density and activity?
A recent study examined the issue. Seven healthy men, average age 27, did five sets of five maximal reps of leg extensions on two occasions separated by one to three weeks. One trial involved a rest protocol, which was called “low testosterone,” while the other featured a high-volume, upper-body resistance workout designed to increase circulating testosterone. Blood tests were done at regular intervals during the training to measure blood testosterone. To check the effects of the training on androgen receptors, biopsies were taken from the subjects’ front-thigh muscles.
Only the high-test workout boosted testosterone above resting values, 12 percent more than the low testosterone trial. Muscle androgen receptors declined during the low-testosterone trial by 43 percent but remained stable during the high testosterone workout. The transient increase in testosterone during the high-testosterone workout worked in only three hours to maintain androgen receptor content. So training in a manner that leads to greater testosterone release will likewise maintain androgen receptor activity, which maximizes the anabolic training effect. Such training involves at least three sets per exercise, featuring short rest periods between sets and working larger muscle groups, such as thighs and back. IM
Spiering, B.A., et al. (2008). Influence of endogenous testosterone concentrations on muscle androgen receptor responses to resistance exercise. J Str Cond Res. 22:31.