The study, which was published in the Journal of the International Society of Sports Nutrition last week, was conducted by Spanish researchers. The researchers are associated with several Spanish universities.
Test included elite, recreational athletes
For test subjects the researchers recruited eight boxers in the country’s national sports program who had been competing for at least two years. They also enlisted 10 ‘trained-recreational’ athletes. The recreational athletes were all students in a sports science program who had been weight training steadily for at least the previous 18 months. All were required to be able to bench press their body weight and perform a squat with 1.5 times their body weight on the bar.
For the caffeine dose the researchers chose 6 mg/kg, which is on the high end of the experimental range. That equates to about 490 mg of caffeine for a 180 lb man, or about 5 average strength cups of brewed coffee.
The test subjects were given the caffeine dosage or a placebo via softgels prepared for the purpose. Then after a 60 minute run-in period they completed profile of mood states (POM) and subjective vitality scale (SVS) questionnaires.
The subjects then did a Wingate test on a cycling ergometer. They were urged to attain maximum power output as rapidly as possible and hold that level throughout the 30 second test. The load was set at 7.5% of the subject’s body weight. After the cycling session the participants were asked to score their rating of perceived effort (RPE) for their leg muscles, their breathing and to give a ‘global’ RPE score.
Caffeine boosted power in both groups, but mood effects differed
The researchers found that their observations of the effect of caffeine matches those of many other studies. “In line with prior work, studies have shown that CAFF supplementation produces an increase in peak and average power and that this effect is not conditioned by the performance level of the athlete,” they wrote.
The found that caffeine helped the boxers reach peak power output on the cycling ergometer almost 10% faster than placebo. For the recreational group, the boost was a whopping 22.5%. The intervention also boosted average power and peak power. One unusual finding was that the recreation group actually developed more power than did the elite athletes, which might reflect the fact that boxers do aerobic exercise with their legs but little strength training per se.
Interestingly, though, the intervention differed in its effects on mood states. For the boxers, the caffeine increased levels of tension prior to exercise, while the recreational athletes showed no statistically significant differences in the mood parameters that were measured.
“Supplementation led to considerable improvements in factors contributing to mood state such as tension, vigor and vitality perception, but only in the elite athletes,” the authors wrote.
Why this is the case proved impossible to parse out in such a small scale and short term study. The authors noted that other studies have postulated that an increase in tension has been shown to be associated with improved performance on Wingate tests, and elite athletes may be accustomed to amping themselves up, so to speak, before a physical task. This may have accounted for the differences between the groups in this regard.
Another limitation of the study was that the researchers were not able to account for any possible caffeine habituation among the participants.
Source: Journal of the International Society of Sports Nutrition
17, Article number: 2 (2020)
Effects of caffeine supplementation on physical performance and mood dimensions in elite and trained-recreational athletes
Authors: Jodra P, et al.
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