Exercise and Androgen Receptor Increase
Research & Development
By the ProSource Product Analysis Team
Feb 26, 2013
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Increasing how your body responds to exercise training is like a chess match. You must balance factors related to your recovery, exercise bouts and nutrition to result in a situation that can facilitate positive improvements in how your body responds. For years, changes in testosterone and other hormones have been studied for their ability to impact changes in muscle. Researchers have clearly shown that various types of exercise, but in particular resistance exercise can favorably impact changes in testosterone and others hormones. When testosterone is increased
in conjunction with resistance exercise, improvements in strength, muscle mass result; other changes include increases in the androgen receptor, a key intracellular component linked to the expression of a number of genes found in muscle linked to strength and muscle changes. Increased expression of genes = increased components to build certain proteins = increased ability to develop strength and promote recovery = good things.
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Identifying optimal programs of exercise that maximize the increases in the androgen receptor would aid in promoting the expression of a number of genes which will positively impact many areas related to how your body responds to resistance exercise. Researchers from the University of Connecticut conducted an examination to accomplish this exact task (Spiering, Kraemer et al. 2009). In both situations, the researchers had young healthy males perform an intense bout of leg extension exercise (5 sets of 5 maximal repetitions with 3 minutes of rest). Previous studies have indicated that resistance exercise which is low volume and is combined with long periods of rest exert little to no impact on changes in testosterone; one of the many reasons why exercise bouts constructed in this manner are said to be better for improving strength
vs. promoting hypertrophy.
In one study condition, the study participants came into the lab and performed no exercise prior to completing the lower-body workout explained previously. The second study condition, however, had the participants first complete a high-volume, upper-body resistance workout with little to no rest between each set and exercise before completing the lower-body workout. In this second condition, the upper-body workout successfully increased blood levels of testosterone prior to completing the lower-body workout. In other words, one condition resulted in the leg workout being completed with low levels of testosterone before the workout began and in the other condition, the lower body workout began and was completed with elevated levels of testosterone
This allowed the researchers to ask and answer the question, "Do elevated levels of testosterone favorably promote adaptations inside the muscle?" Besides measuring testosterone levels in the blood, muscle biopsies were collected before, 10 minutes after completion of the lower body exercise bout and three hours after the lower body exercise bout. Changes in the androgen receptor, an important receptor found in muscle that testosterone binds to and cause the expression of a number of favorable genes related to positive strength and muscle changes, were analyzed in each of the collected muscle samples.
The authors determined that when a lower-body exercise bout was completed in an environment with elevated levels of testosterone (when the high-volume, low rest upper-body exercise session was completed beforehand) that the content of the androgen receptor was not decreased after three hours. In comparison when no exercise was completed beforehand, the content of the androgen receptor was decreased. The authors concluded that creating an environment that maximizes the interaction of testosterone with its receptor, the androgen receptor, will favorably impact muscle anabolism and recovery. Thus it appears that structuring your workout to improve muscle anabolism and recovery are two chess pieces worth moving where you want to move them.
Spiering, B. A., W. J. Kraemer, et al. (2009). "Elevated endogenous testosterone concentrations potentiate muscle androgen receptor responses to resistance exercise." J Steroid Biochem Mol Biol 114(3-5): 195-199.
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