The lower testosterone values in the study by Chandler et al. (8) occurred at the same time insulin concentrations were elevated, suggesting an interaction between these two anabolic hormones. Interestingly, the same inverse pattern of response between testosterone and insulin was also observed in this study. That is, when insulin concentrations were highest, testosterone concentrations were lowest, and when insulin concentrations were lowest, testosterone concentrations peaked. In support of our data and those of others (8), it has been shown that in adult men insulin is negatively correlated with both testosterone and SHGB (41, 46). Additionally, there may have been an increase in biologically active or free testosterone despite a lower total testosterone during supplementation. An indirect measure of the biologically active testosterone, the free-androgen index (total testosterone/SHGB), was not significantly different between supplement and placebo conditions. Thus, although total testosterone was lower at some time points during the supplement condition, it is very likely that the biologically active free testosterone was not different. Finally, it is possible that there was a greater clearance of circulating testosterone or a reduction in secretion after exercise and supplementation. The relative contributions of these mechanisms to circulating testosterone during intense exercise and dietary supplementation require further investigation.
Thanks for posting this. It is interesting.
I wonder if when consuming high GI carb (such as Surge) post WO, which acts to elevate insulin and deliver the glucose and aminos to the trained and recovering muscle, if T has a synergistic effect with the insulin in delivering those nutrients into the muscle cell and therefore, circulating T is reduced as it binds to the muscle receptors along with insulin binding to it’s receptors, so that each imparts an anabolic effect in the uptake of these nutrients post WO and triggers protein synthesis. I guess I’m speculating that sufficient T available to bind to muscle androgen receptors when in the presence of insulin, act synergistcally to increase protein synthesis more than either individually. The sum effect is greater than the individual sums of insulin and T?