If you end a strength training session with a high reps set so that your muscles produce extra lactic acid [structural formula shown below], it’s likely to increase your natural testosterone production. We, the ever-alert compilers of this web magazine, deduce this from a Taiwanese cell study published in 2001 in the Journal of Cellular Biochemistry. The study shows that lactic acid increases testosterone production through the Leydig cells.


Strength training raises testosterone levels. The researchers wanted to know more about how this works, so they focused on the Leydig cells in the testes. These are the cells that convert cholesterol into testosterone under the influence of LH and FSH.



The researchers added increasing concentrations of lactic acid to the rats’ Leydig cells that they had put into test tubes. By way of comparison they also exposed the cells to LH. The figure below shows that the Leydig cells produce more male hormone, the higher the concentration of lactic acid, but that LH does not have as great a stimulatory effect as lactic acid.

Lactic acid is the key – and here's why

The researchers write that they did trials with higher concentrations than those shown in the figure. But then the effect was reversed, and testosterone production went down.

The researchers also exposed the cells to substances like forskolin, which stimulates cAMP. CAMP is a second messenger, a molecule that passes on signals from activated receptors to the cells. This effect more or less disappeared, which led the researchers to conclude that lactic acid works in the same way as cAMP does.

Lactic acid is the key – and here's why

In other experiments the Taiwanese discovered that lactic acid is active mainly in the first phases of testosterone biosynthesis. Lactic acid has little effect if you give Leydig cells testosterone precursors like androstenedione and progesterone. But lactic acid does increase the production of StAR protein. This is a protein that brings cholesterol into cells, where it is converted into steroid hormones.

The Taiwanese study is interesting for natural athletes who want to optimise their muscle building. The more your strength training stimulates testosterone production, the better your muscle bulk and power results will be.


J Cell Biochem. 2001 Jun 26-Jul 25;83(1):147-54.