Effects of caffeine consumption before resistance exercise on blood levels of testosterone and growth hormones in male athletes

Caffeine has the athletic performance-enhancing effects, but its effect on concentrations of anabolic hormones is unclear. Therefore, this research examines the short–term effect of caffeine consumption on anabolic hormones of growth (GH) and testosterone (TS) after performing resistance exercise (RE).

In this randomized double-blind, and placebo-controlled crossover study, 30 volunter men (mean age 21.72 ± 4.06, height 179.31 ± 5.08 centimeter, wight 77.31 ± 14.70 kilogram) who did resistance exercise consumed caffeine supplement (6 mg.k-1 of the body weight) and placebo (maltodextrine 6 mg.k-1 of the body weight) one hour before the RE, and the blood samples were taken before, after and 15 min after RE.

 Analysis of data showed that GH concerntration showed a significant difference between the conditions of caffeine and placebo immediately and and 15 minutes after RE (P<0.05), but no significant diference was found in TS concentration caffeine and placebo groups at any times.

In general, the present study indicated that caffeine (6 mg.k-1) leads to the significant increase in GH concentration after RE (85% of 1RM) in athletes, but, it had not any effect on the concentration of TS