Dr. Dwayne Jackson

The Vital Science Blog

Starting Living Your Best

A cup of mojo

Many athletes regularly use caffeine to increase mental focus, combat fatigue, and increase strength. We all know that as little as one cup of coffee can help increase exercise intensity, especially when we have had suboptimal periods of sleep. Science supports caffeine as an ergogenic aid; thus, it stands to reason why most pre-workout powders are chock-full of this stimulant.


In a 2012 study published in the International Journal of Sport Nutrition and Exercise Metabolism researchers have shown that pre-workout caffeine can overcome poor workout performance due to sleep deprivation. In this double-blind crossover study, 16 professional rugby players received either caffeine (approximately 400mg) or a placebo 1 hour prior to exercise. Based on the subjects reported sleeping habits, they were considered either sleep deprived (6 hours or less per night) or non-deprived (8 hours or more per night). The subjects performed 4 sets each of bench press, squats, and rows at 85% of their predetermined 1 RM and were instructed to carry out as may reps as they could for each set. Testosterone and cortisol were measured from saliva that was sampled before supplementation, pre-workout, and post-workout. As expected, sleep deprivation led to significant decreases in total workout load; however, sleep deprived subjects who took caffeine performed as well as those who were well rested. Notably, non-deprived individuals who received caffeine performed better than all groups. Most remarkably, caffeine ingestion boosted testosterone levels pre- and post-workout in non-deprived subjects; however, there was an increase in cortisol levels associated with caffeine ingestion, which was greatest in sleep-deprived subjects. 


This was a well-executed study on a relevant population. It should be noted that 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! Although the finding that catabolic cortisol also went up with caffeine is disheartening (but not surprising), there is light at the end of the tunnel. By digging a little deeper into the data (and doing a little math) it is apparent that their findings are in favor of a net anabolic effect of caffeine supplementation. Just remember that this heightened anabolic effect is only notable if you get a good nights sleep!     


ACTION POINT: To reap the anabolic and energizing benefits of pre-workout caffeine, get 8-hours sleep per night and take 200-400 mg caffeine 30minutes before training.  



Cook C1, Beaven CM, Kilduff LP, Drawer S. Acute caffeine ingestion’s increase of voluntarily chosen resistance-training load after limited sleep. Int J Sport Nutr Exerc Metab. 2012 Jun;22(3):157-64.

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