Caffeine is gaining approval as a safe performance-enhancing aid in sports and daily life. New research shows it will improve reaction time, delay fatigue, and lower feelings of pain.
The new study in the journal Nutrition and Metabolism tested the effect of a pre-workout supplement containing 300 mg of caffeine, 6 g of BCAAs, and vitamins B6 and B12. The BCAAs were included because they improve protein synthesis and have a protective effect on the muscle from damage due to loaded exercise. Vitamin B6 was included because it plays an important role in the metabolic pathways required for exercises, and B12 assists with DNA synthesis and training capacity.
Results showed that the supplement improved alertness, perceived energy, focus, various measures of reaction time, and muscular endurance. The participants felt less fatigue and lower rating of perceived exertion (RPE) from taking the caffeine supplement compared to the placebo. Because caffeine acts as a painkiller, it can reduce the muscle pain experienced with heavy training.
Researchers suggest that caffeine improves athletic performance by blocking the action of adenosine receptors on the cells. Less sensation of pain increases neurotransmitter release and motor firing rate, which is why reaction time and focus improve. The benefit of increased motor firing rate is more efficient muscle contractions, which is the reason other studies have found caffeine can allow you to lift more weight.
The caffeine supplement also delayed fatigue and increased energy in the reaction time tests—participants actually performed better as they progressed through the series of tests. Around 95 minutes into the exercise, the placebo group’s performance dropped off significantly, whereas the supplement group reacted faster in the final stages of the test.
Of interest, a recent study in the Journal of the International Society of Sports Nutrition found that if you have a certain gene polymorphism, or genetic variety, you will be more sensitive to caffeine. This study showed that people who had a genetic variation called CYP1A2 experienced significantly greater performance benefits from ingesting 6 mg per kg of bodyweight of caffeine.