You already know that caffeine can help keep you alert, increasing your focus and concentration when you need to finish that paper or get through that Monday 8:00 am meeting. (Of course, too much may keep you up at the wrong time, too.) Evidence continues to mount that it can also help you go the extra mile… literally.
It is well-established that caffeine enhances athletic performance, but the research is wide-ranging and sometimes contradictory. In an effort to consolidate the best evidence, the International Society of Sports Nutrition just released a position statement on caffeine and athletic performance.
Overall, caffeine is effective for improving athletic performance. The degree of improvement depends on several factors, including the duration, intensity and type of exercise, the condition of the athlete (higher-trained athletes tend to reap more benefits at higher levels of intensity and performance), and the previous caffeine habits of the user (non-habitual users may get a longer endurance boost at first). Caffeine can improve performance in endurance sports like running, swimming and cycling, consistent with its possible influence on the Central Nervous System and on muscles’ increased use of fat for energy. It also may help you recover from exercise. Why? When taken after exercise, caffeine may aid recovery by helping your liver and muscles re-synthesize glycogen. But monitor your overall caffeine intake if you take it both before and after exercise so as to avoid unwanted side effects
One likely cause is the same reason caffeine makes you alert- it acts on your brain and central nervous system (CNS). One study cited in the position statement noted that athletes using caffeine began exercise at a higher intensity than they did on placebo, but did not notice a difference in effort. Another possible explanation for caffeine’s benefit is that your muscles use more fat for energy and less glycogen (carbohydrate), which boosts endurance and delays your time to exhaustion.
For trained athletes, caffeine is beneficial for team sports that combine endurance with short bursts of high intensity, including soccer, hockey, and rugby. Besides increased endurance, studies have shown improvements in passing accuracy and ball control in trained soccer and rugby athletes taking caffeine, suggesting enhanced fine-motor skills. Research is limited and inconsistent with regard to caffeine and strength training or other exercise of high intensity and short duration. More studies are needed before recommendations can be made. One potential concern about caffeine and sports is that caffeine is normally (at rest) a diuretic, increasing urine volume and potentially causing dehydration. Proper hydration is obviously very important for athletic performance and overall health. During exercise, however, caffeine does not exhibit significant diuretic effects. Studies have not shown differences in fluid balance, urine volume or sweat rates during exercise for athletes on caffeine.
- Caffeine is more potent in capsule or powdered form than as part of a drink (like coffee, tea, or sports drinks). However, coffee and tea lovers need not worry, as all forms of caffeine are still effective, and coffee and tea also offer additional potential health benefits.
- The optimal window to consume caffeine is 30-60 minutes before exercise, although it has sometimes shown to improve performance as quickly as 15 minutes prior.
- Caffeine works at low-to-moderate doses (about 3-6 mg caffeine per kg of body weight) and does not provide greater benefit at higher doses (9 mg/kg). Here are the approximate dosage ranges for 3-6 mg/kg for approximate body weights:
- 120-lb person: 160-330 mg caffeine
- 150-lb person: 200-400 mg caffeine
- 180-lb person: 250-500 mg caffeine
- 210-lb person: 285-575 mg caffeine
Here is a reference list of the caffeine content of various drinks. Remember, even the low end of the range is sufficient, so 16 oz of home-brewed coffee is enough for most people. Not only are very high doses not beneficial, they can also cause harmful side effects. These include anxiety, nausea, vomiting, tremors, increased heart rate, and difficulty sleeping, the last of which should also be noted as being especially detrimental to athletic performance (not to mention your overall health).