Journal Title (Medline/Pubmed accepted abbreviation): J. Inl. Soc. Sports Nutr.
Background:Sleep deprivation can cause a lack of energy and cognitive performance, thereby impacting the ability to perform skills that require high coordination and/or focus. Caffeine has been established to be able to partly compensate for sleep deprivation in regards to physical performance. Recently, because of the brain’s creatine requirements, creatine has been proposed to do the same.
Hypothesis: When sleep deprived, rugby athletes will be able to pass more accurately while running when they have consumed low to moderate doses of caffeine or creatine vs. a placebo.
Subjects:10 professional rugby backs, age 20 ± 0.5
Experimental design:randomized, single-blinded (athletes were blinded to the treatment)
The players were first familiarized with a rugby-specific passing-while-running skill (3 wks, 12 sessions total). They sprinted 20 m and, at 10 m, passed a rugby ball left or right (alternating) through a 1.5 m diameter hoop 10 m away from them. For trials with adequate sleep, the players were required to get 7-9 hrs of sleep on the 2 nights proceeding the trial. For trials where they were sleep deprived, they got 3-5 hrs of sleep the night before, but at least 7 hrs of sleep 2 nights before the trial. Sleep logs were kept by subjects to ascertain the amount of sleep the night before the test. The article did not mention potential factors contributing to sleep deprivation. However, subjects did obstain from alcohol for at least 48 hours prior to any testing and caffeine-containing drinks for at least 24 h before testing. Subjects had not used creatine supplements for at least 3 months preceding the study.
At 10:00 am, before their 11:30 am trial, subjects consumed:
- a placebo (5 mg/kg body weight of sucrose),
- creatine (50 or 100 mg/kg = 3.5 or 7 g for a 154 lb person, 5 or 10 g for a 220 lb person), or
- caffeine (1 or 5 mg/kg body weight = 70 or 350 mg for a 154 lb person, 100 or 500 mg for a 220 lb person).
Participants completed 10 sessions total- 5 sleep deprived and 5 not, with placebo and the 4 treatments so that each combination was performed once.
Performance was measured by number of times the ball went through the hoop. Saliva samples were also acquired immediately before the trial for measure of testosterone and cortisol. (Cortisol is associated with arousal but also stress.)
Creatine and caffeine appear to at least partly compensate for sleep deprivation in performance of the rugby ball-passing task. It also appears that 1 mg/kg bodyweight of caffeine is sufficient for performance enhancement (80 mg caffeine for a 176 lb person = 1 cup of instant coffee or 6-8 oz. of a commercial energy drink). Creatine at 100 mg/kg bodyweight had the largest effect on performance and appeared to increase accuracy slightly in non-sleep deprived athletes as well (though differences were not significantly different).
Because caffeine in the bloodstream peaks 30-90 min after ingestion, the 90 min separation between ingestion and test in this study may have been too long to reap optimal benefits from the caffeine treatment. These athletes were not regular caffeine consumers, so they may have shown a higher sensitivity to the caffeine. It would be interesting to see if caffeine and creatine have additive effects in regard to sleep deprivation and physical or cognitive performance.