Introduction:
Caffeine is one of the most commonly consumed stimulants in the world. Found in common beverages consumed daily by students, graduates, and office workers, such as coffee, tea, soda, pre-workout supplements, and many energy drinks to name a few, the consumption of caffeine has been a popular medium in a daily routine. Among teenagers and young athletes, caffeinated products are often consumed, believing that they provide more energy and improve athletic performance; however, there is a slight misconception as caffeine works mainly by affecting the central nervous system, where it can reduce feelings of tiredness and increase alertness. But, the important question is whether feeling more energized actually translates into measurable improvements in physical performance.
A study examined whether caffeine could improve strength, jumping ability, muscular endurance, agility, and aerobic endurance in adolescent athletes. The researchers were also interested in whether genetics affected how strongly caffeine worked. Specifically, they examined variations in a gene called CYP1A2, which helps produce an enzyme responsible for breaking down caffeine in the body. Some people metabolize caffeine differently because of variations in this gene. The researchers therefore wanted to determine both whether caffeine improves athletic performance in teenagers and whether those improvements depend on genetics.
Methods:
The study included 100 adolescent athletes with an average age of 15 ± 2 years. Participants consumed either caffeine (6 mg/kg of body weight) or a placebo about one hour before completing a series of physical tests: handgrip strength, vertical jump performance, agility, push-ups, sit-ups, and aerobic endurance using the Yo-Yo Intermittent Recovery Test. The Yo-Yo test measures how long an athlete can repeatedly run back and forth at increasing speeds before becoming exhausted. Researchers also examined participants' CYP1A2 gene variants, which can influence how quickly the body breaks down caffeine, to determine whether genetics changed caffeine's effect on athletic performance.
Results:
Caffeine improved some types of athletic performance, but was limited in pervasive improvement. For muscular endurance, participants completed an average of 37 ± 9 sit-ups after caffeine compared with 35 ± 8 after the placebo, representing a 5.7% increase. Participants also completed 26 ± 11 push-ups with caffeine compared with 24 ± 11 with the placebo, a 8.3% increase. Both differences were statistically significant (p < 0.05). In simple terms, the researchers found enough evidence to suggest that these differences were probably related to caffeine rather than simply random variation between testing sessions.
The largest practical improvement appeared in the Yo-Yo endurance test. After consuming caffeine, participants ran an average of 1,010 meters, compared with 903 meters after the placebo. Approximately 107 meters, or nearly 12%, suggesting that caffeine may have helped participants maintain repeated running efforts for longer before becoming exhausted; however, caffeine did not significantly improve several other performance measurements. Handgrip strength was 35.1 kg-force with caffeine versus 33.7 kg-force with the placebo. Countermovement jump height was 49.3 cm versus 47.9 cm, while spike-jump height was 54.2 cm versus 52.9 cm. Agility times were almost identical at 15.8 seconds with caffeine and 15.9 seconds with the placebo. For these measurements, the differences were not statistically significant (p > 0.05). Therefore, even though some caffeine averages were slightly higher, researchers could not confidently conclude that caffeine caused those differences.
Interestingly, the participants' CYP1A2 genotype did not significantly change the benefits of caffeine. Although these genetic differences can affect caffeine metabolism, the study found that when caffeine improved performance, the improvement occurred regardless of whether participants carried the AA, AC, or CC version examined by the researchers.
There are also important limitations: the caffeine dose used was 6 mg/kg, which would equal about 360 mg of caffeine for a 60-kg (132-lb) teenager. Therefore, this study should not be interpreted as evidence that teenagers should consume large amounts of caffeine or energy drinks. The experiment investigated the short-term effect of a controlled dose of caffeine on athletic performance, not whether regular caffeine consumption is healthy or safe for adolescents. A recent systematic review of caffeine research in adolescent athletes similarly concluded that evidence for performance benefits remains limited and uncertain overall and does not support routinely recommending caffeine for youth sports.
Another limitation is that performance was measured shortly after a single caffeine dose. The study does not tell us what happens when adolescents regularly consume caffeine, develop caffeine tolerance, combine caffeine with energy-drink ingredients, or experience side effects such as disrupted sleep.
Conclusion:
Overall, caffeine improved some types of athletic performance, especially muscular and aerobic endurance. Participants completed about 5.7% more sit-ups, 8.3% more push-ups, and nearly 12% more distance on the Yo-Yo endurance test, but caffeine did not significantly improve grip strength, jumping ability, or agility. These findings suggest that caffeine may help adolescent athletes exercise for longer rather than become immediately stronger or more explosive. However, the study used a relatively high, controlled dose of caffeine, so the results do not mean that teenagers should regularly consume caffeine or energy drinks. More research is needed to understand its long-term effects and safety in adolescents.
