In addition, during heavy strength and weight training, the adrenal glands release testosterone. The job of testosterone is to promote protein synthesis and support production of new red blood cells, which increase the body’s ability to utilize oxygen more effectively, which then leads to more efficient usage of glucose. Besides that, testosterone is one of the main hormonal communicators of the muscle tissue repair process. In other words, the elevated testosterone levels help you perform better during strenuous exercise, and thus cause bigger gains, which is why athletes love it so much.
An influential 21-week study by Ahtiainen J.P. et al. showed a correlation between T levels and the changes in isometric strength and muscle size, which means that both serum basal testosterone concentrations and training-induced acute testosterone responses are strongly associated with muscle and strength gains.
Exercise-Derived Testosterone and Muscle Growth
Furthermore, different types of training have specific effects on hormonal changes and studies have shown that some exercises cause the body to release more testosterone than others. Of course, we’re talking about heavy compound exercises, which have been found to elicit a higher testosterone release. Still, this doesn’t necessarily mean that it’s the acute bumps in T that lead to more muscle growth – could it be some other factor?
One big study by West et al. provides an answer to this question. The researchers wanted to know if the increased testosterone production derived from leg exercises would cause an increase in muscle gains, so they made 12 healthy young men train their biceps for 15 weeks on separate days and under different hormonal conditions. To stimulate low testosterone conditions, the subjects performed only arm curls.
To achieve high testosterone conditions, they performed arm curls followed immediately by a high volume of leg exercises (5×10 of leg presses and 3×12 of leg extension/leg curl supersets). But the most interesting part of the study was that each subject also served as his own control by exercising one arm under high testosterone conditions (arm curls followed by leg exercises) and the other arm on a different day under low testosterone conditions (only arm curls). Their line of reasoning was that if exercise-induced increases in testosterone production really leads to bigger muscle gains, there should be a discrepancy in the muscle size gained in each arm in favor of the arm that was trained under high testosterone conditions.
However, the results showed that although strength and muscle size increased in both arms, the increase wasn’t bigger in the arm that was trained under high testosterone conditions. But another study, conducted by Ronnestad, B.R. et al., had the opposite outcome. In this study, the subjects performed the high-volume leg exercises first, and the arm exercises second, and the result was a greater hypertrophy response in the biceps!
Could the order of the exercises be the key part of promoting bigger lean gains with the help of exercise-derived testosterone? We can’t say for sure. You’ve probably realized so far that science is complicated and messy and can rarely provide straight-forward answers and solutions, so let’s avoid getting our hopes too high.
That’s what Phillips et al. thought when they decided to investigate a bit deeper into the same data collected by Ronnestad and found that there were no significant changes in arm size. But to make matters even more bizzare, West et al. then looked at Phillip’s data from another perspective and claimed that the increases in lean body mass originally reported by Ronnestad were real but weren’t actually caused by testosterone levels but were directly associated with changes in cortisol, the much-hated stress hormone.
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