Skill execution and sleep deprivation: effects of acute caffeine or creatine supplementation – a randomized placebo-controlled trial


Journal Title (Medline/Pubmed accepted abbreviation): J. Inl. Soc. Sports Nutr.
Year: 2011
Volume: 8
Number:2

Summary of Background and Research Design

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)

Treatments/Protocol: 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.)

Summary of research findings:
  • In the familiarization sessions, no difference was noted in performance through sessions 5-12. There was no more than a 5% variance in performance after adequate sleep and there was no more than 15% variance among individuals.
  • Creatine and caffeine both showed increased performance after sleep deprivation on both dominant and non-dominant passing sides. For the dominant side:
    • The average performance with sleep deprivation and a placebo was about 7.3 ± 0.6 (of 10 attempts) whereas without sleep deprivation and with placebo average performance was about 9.0 ± 0.5.
    • Either creatine or caffeine at any dose resulted in a statistically significant increase in performance after sleep deprivation compared to the placebo (p < 0.001). Average performance with sleep deprivation and 50 mg/kg creatine and either dose of caffeine was about 8.9 -9.0 ± about 0.6 (see manuscript for exact values for each treatment). Performance with the 100 mg/kg dose of creatine was higher, at about 9.4 ± 0.6, but these differences did not reach statistical significance.
    • The average performance for the placebo, 50 mg creatine/kg, and 1 and 5 mg/kg caffeine was about 9/10 for non-sleep deprived sessions whereas it was nearly 10/10 with 100 mg creatine/kg. With the standard deviation (± about 0.6) these differences were not statistically significant.
    • Caffeine nor creatine was able to increase performance past that of non-sleep deprivation, but there was no statistical difference between sleep deprivation and non-sleep deprivation with any of the treatments (except placebo). There was also no statistical difference when comparing non-sleep deprivation + placebo with sleep deprivation + either dose of caffeine or creatine.
  • For the non-dominant passing side, the trend was similar to the dominant side, though accuracy was down about 10%.
  • Testosterone levels were slightly higher for the non-sleep deprived athletes than the sleep deprived athletes (nonsignificant, p = 0.209). 100 mg/kg creatine elicited a somewhat greater testosterone response (nonsignificant, p=0.067) than the other treatments.
  • Caffeine at 5 mg/kg was correlated with a significantly higher level of salivary cortisol (p=0.001) compared to the placebo treatment.

Interpretation of findings/Key practice applications:

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).

Limitations:

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.
Google Tracking Google Plus Tracking Twitter Tracking