Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "
Animal study: CLA + endurance training = more testosterone
Indeed, the Italians did not do an experiment with real live humans; instead they used male mice. On the other hand, the Italians used a product that can be found everywhere: Tonalin FFA. This contains a mixture of equal parts of the CLA isomers cis-9,trans-11 and trans-10,cis-12, whose structural formulas are shown below.
If you put testes cells in a test tube, then they'll produce more testosterone if you expose them to CLAs. This effect is shown below. It's not massive, but the Italians' results indicate that the increase in testosterone is considerably higher in organisms that engage in physical exertion.
The researchers got half of their mice to run five days a week. At the start of the experiment the mice ran 15 minutes each day; at the end of the experiment after six weeks, the mice ran 60 minutes a day. Throughout the period the researchers also stepped up the speed at which the mice ran from 3.2 to 4.8 metres per minute.
Half of the mice were given a daily dose of CLAs [CLA-TR] orally just before they exercised, the other half got nothing [PLA=TR].
One group of mice did not run: this was the control group. Half of the animals in the control group were given CLAs [CLA=SED]; the other half were given nothing [PLA-SED].
The combination of training and CLA supplementation boosted the amount of the enzyme CYP17A1 in the testes of the mice.
The figure above illustrates the part of the biosynthesis of testosterone where CYP17A1 plays an important role. The enzyme converts progesterone into androstenedione, a direct precursor of testosterone.
The Italians also discovered that CLA supplementation led to an improvement in performance. It boosted the increase in the mice's leg-muscle mass, boosted the increase in strength in the mice's legs and also helped the mice to run greater distances. The researchers speculate that these effects may well be the result of increased testosterone synthesis.
"Because of the endogenous effect of CLA supplementation on testosterone production, this food supplement, in association with physical activity, may be used as an ergogenic aid in different fields of interest, including in sport science to enhance the positive effect of training on muscle mass and performance, in cachexia and anti-aging therapy to reduce the muscle wasting, and in human reproductive medicine to help aid in spontaneous conception or to increase the chance of conception with assisted reproductive treatment", the researchers conclude.
They note though that mice are not men. "Because this study was performed in mice, the results reveal its limitation on species generalisation", they write. "Thus, future research in other animal models and humans are needed to confirm these findings."
The study was not financed by the supplements industry.