By Dwayne N. Jackson, PhD
Many athletes regularly use caffeine to increase mental focus, combat fatigue and increase strength. We all know as little as one cup of coffee can help increase exercise intensity, and is especially helpful when you’re short on sleep. Science supports caffeine as an ergogenic aid, so most preworkout powders are understandably chock-full of this stimulant. You’ve no doubt read about the several research-backed benefits of preworkout caffeine ingestion, which include increased muscle building, strength, fat loss, recovery, and energy level. However, a new study shows caffeine has the power to do even more!
In a study recently published in the International Journal of Sport Nutrition and Exercise Metabolism, researchers have demonstrated preworkout caffeine can combat poor workout performance as a result of sleep deprivation. In this double-blind crossover study 16 professional rugby players received either caffeine (approximately 400 milligrams) or a placebo one hour before exercise. Based on the subjects’ reported sleeping habits, they were considered either sleep deprived (six or fewer hours per night) or nondeprived (eight or more hours per night). The subjects performed four sets each of bench presses, squats and rows at 85% of their 1RM. They were instructed to complete as may reps as they could for each set. Researchers measured testosterone and cortisol levels from saliva that was sampled at three times: before supplementation, preworkout and post-workout. As expected, sleep deprivation led to notable decreases in total workout load. However, sleep-deprived subjects who supplemented with caffeine performed at the same level as those who were well rested. Notably, well-rested athletes who received caffeine performed better than all other groups. Furthermore, caffeine ingestion boosted testosterone levels pre- and post-workout among well-rested subjects. Unfortunately there was also an increase in cortisol levels associated with caffeine ingestion, which was greatest among sleep-deprived subjects. Use caffeine in moderation!
THE DOC’S TAKE
This was a well-executed study on a relevant population. Only 50% of the group responded to caffeine supplementation; the others were deemed caffeine insensitive. Most intriguing were the hormonal data illustrating that caffeine boosts testosterone levels, whether you’re sleep deprived or not. In contrast, the finding that catabolic cortisol also went up with caffeine is disheartening but not overly surprising. However, there is hope for all of you who are caffeine enthusiasts — or even addicts! By digging a little deeper into the data and doing a little math, we’ve extrapolated that the researchers’ findings are in favor of a net anabolic effect of caffeine supplementation. Just remember this heightened anabolic effect is most apparent if you regularly get a good night’s sleep.
Cook C, Beaven CM, Kilduff LP, Drawer S. Acute caffeine ingestion increases voluntarily chosen resistance training load following limited sleep. Int J Sport Nutr Exerc Metab. 2012 Feb 15. [Epub ahead of print]