Sunday, September 12, 2010

60% More Testosterone by 10 x 5 Reps of Speed Squats at 70% of Body Weight

We all know that intense exercise is the way to trigger hormonal responses and muscle hypertrophy in the gym. Now a study by Fry & Lohnes (Fry. 2010) quantified this effect to +60% increase in testosterone. The scientists had four weight trained men perform 10 x 5 speed squats at 70% of system mass (1 RM +/- BW) with 2 min inter-set rest intervals. Five minutes upon completion of the workout blood was drawn and cortisol and testosterone levels were analyzed:
Post-exercise Tes exhibited a very large effect size (nmol x L-1 pre = 12.5 +/- 2.9, post = 20.0 +/- 3.9; Cohen's D = 1.27).
What is confusing, however, is that the scientists state that while cortisol did not change the cortisol/testosterone ratio would not be influenced, only to conclude:
The acute increase for Tes is in agreement with previous reports that high power activities can elicit a Tes response. High power resistance exercise protocols such as the one used in the present study produce acute increases of Tes. These results indicate that high power resistance exercise can contribute to an anabolic hormonal response with this type of training, and may partially explain the muscle hypertrophy observed in athletes who routinely employ high power resistance exercise.
This observation, on the other hand, makes sense only under the assumption that there was a significant effect on the testosterone/cortisol ratio.
Figure 1: Lactate and hormonal responses (X ± SD) before and after the high power resistance exercise and control sessions. * Different from pre (p < 0.05). The Cohen’s D value for total testosterone represents a very large effect size. (Fry. 2010. Fig. 3)
In view of the graphs in figure 1, the numbers are in fact put into perspective, because there is an increase in cortisol (fig.3 C) which compensates part of the anabolic response associated with the 60% increase in testosterone. In spite of all that, the study gives you another good reason to do your squats!