From Ergo Log
Interval training doesn't lower the level of anabolic hormones in the body, but many studies show that it raises the production of cortisol – which is catabolic – although not as much as endurance training does. Biochemists at Taipei Physical Education College discovered that supplementation with 50 mg DHEA makes the hormonal response to interval training even better.
DHEA is a pro-hormone. Enzymes in the body convert it into androstenedione, estradiol and testosterone. Although DHEA trade is officially forbidden in the EU, the substance is readily available in Europe. In nearly all other countries DHEA is a legal supplement.
Sports scientists and endocrinologists have studied DHEA in detail, but most of the research has had disappointing results, for athletes at least. One is example is the study that researchers at Iowa State University published in 1999. [J Appl Physiol. 1999 Dec; 87(6): 2274-83.] In this study supplementation with 150 mg DHEA daily did not have a positive effect on the hormone balance of young men who did weight training, nor did it have an effect on body composition.
But the Taiwanese didn't give up there. They went on to study the effects of DHEA on eight young men in their early twenties and on eight men in their late forties. The men took 50 mg just before going to bed and the next day at eight o'clock in the morning they did an interval training session. This consisted of five short sprints (2 minutes in length) in which the men cycled at 100 percent of their maximal oxygen uptake. The men took one-minute rests between sprints.
Immediately before and after the interval training session the researchers analysed the men's blood. The researchers also repeated the experiment after the men had taken a placebo.
They saw that the interval training had no noticeable effect on the men's free testosterone level. But DHEA supplementation raised the testosterone level in all of the men.
The second figure above shows that DHEA had hardly any effect on the cortisol level.
But DHEA did have an effect on the free testosterone:cortisol ratio. This rose, which is good news. The higher the ratio, the more easily the body recovers from physical exertion and builds up muscle mass. At least, that's what you'd expect. Whether this actually happened in the test subjects the researchers didn't measure.
So interval training doesn't affect the concentration of free testosterone the Taiwanese write. "More importantly, we provide convincing evidence that oral DHEA administration can rapidly raise the free testosterone levels of middle-aged men to levels comparable to that of young men, and this increase is well maintained after acute high-intensity interval training."
Eur J Appl Physiol. 2013 Feb 17. [Epub ahead of print].