Sunday, June 22, 2008

Caffeine and Testosterone--Is There a Connection?

Does caffeine raise testosterone? Can it be true? Is all my coffee drinking as of late increasing my testosterone levels too! Well, it looks like it may be true, but hold on their Tex as the effect is ameliorated (canceled) by an increase in cortisol (a muscle munching hormones a Dr. Lowery likes to say). Looks like the end result is probably nothing to write home about--drat. The high end is a pretty high dose of caffeine too with a 800 mg does used in the study and a standard (not Starbucks mongo sized version) coming in at about 120 mg caffeine per serving as a comparison. Be sure to check out my other ramblings on caffeine HERE.
Here is the study

Dose effect of caffeine on testosterone and cortisol responses to resistance exercise.

Int J Sport Nutr Exerc Metab. 2008 Apr;18(2):131-41.

Beaven CM, Hopkins WG, Hansen KT, Wood MR, Cronin JB, Lowe TE.

Horticulture and Food Research Institute of New Zealand, Hamilton, New Zealand.

INTRODUCTION: Interest in the use of caffeine as an ergogenic aid has increased since the International Olympic Committee lifted the partial ban on its use. Caffeine has beneficial effects on various aspects of athletic performance, but its effects on training have been neglected.

PURPOSE: To investigate the acute effect of caffeine on the exercise-associated increases in testosterone and cortisol in a double-blind crossover study.

METHODS: Twenty-four professional rugby-league players ingested caffeine doses of 0, 200, 400, and 800 mg in random order 1 hr before a resistance-exercise session. Saliva was sampled at the time of caffeine ingestion, at 15-min intervals throughout each session, and 15 and 30 min after the session. Data were log-transformed to estimate percent effects with mixed modeling, and effects were standardized to assess magnitudes.

RESULTS: Testosterone concentration showed a small increase of 15% (90% confidence limits, +/- 19%) during exercise. Caffeine raised this concentration in a dose-dependent manner by a further small 21% (+/- 24%) at the highest dose. The 800-mg dose also produced a moderate 52% (+/- 44%) increase in cortisol. The effect of caffeine on the testosterone:cortisol ratio was a small decline (14%; +/- 21%).

CONCLUSION: Caffeine has some potential to benefit training outcomes via the anabolic effects of the increase in testosterone concentration, but this benefit might be counteracted by the opposing catabolic effects of the increase in cortisol and resultant decline in the testosterone:cortisol ratio.

Publication Types: Randomized Controlled Trial
PMID: 18458357 [PubMed - indexed for MEDLINE