by Jeff S. Volek, Ph.D., R.D.
Caffeine has been described as the World’s most popular drug. That’s right, technically caffeine is considered a drug since it stimulates the brain and has mood-altering and metabolic effects. But it’s also considered a nutrient found naturally in coffee, tea and chocolate. What can you reasonably expect from ingesting caffeine? The answer may surprise you. Here’s a sampling of research findings to give you a sense of what caffeine intake does to the body. Caffeine improves endurance performance
Going back more than 3 decades, studies consistently show that caffeine ingested before endurance exercise causes a modest performance enhancement. For example, in one recent study caffeine ingested one hour before exercise resulted in a 5% improvement in endurance performance. The performance boost was evident when caffeine was given as a supplement or coffee, suggesting the
source of caffeine is not important. Caffeine improves high intensity and strength performance
Caffeine is not just for endurance athletes. Australian researchers examined the effects of ingesting caffeine or placebo 1 hour before 60 minutes of cycle sprints with short rest periods. The dose of caffeine was 6 mg/kg body weight (about 450 mg based on a 165 pound person), which is equal to about 2-3 cups of brewed coffee. Compared to placebo, caffeine intake resulted in a 7-8% increase in peak power and total work.
In another study, moderately trained men completed as many bench press repetitions as possible with a load equal to 60% of their one repetition maximum. Subjects consumed 5 mg/kg body weight of caffeine (about 375 mg) or placebo 1 hour before exercise. Subjects completed 20.4 reps after placebo and 22.4 reps after caffeine. Participants also reported that they felt more vigorous and less fatigued in the caffeine condition. Caffeine reduces muscle soreness
In another study, subjects performed 4 sets of 10 bicep curls followed by a fifth set to exhaustion. Subjects consumed 5 mg/kg body weight of caffeine (about 375 mg) or a placebo one hour before the test. Subjects performed 18 reps after caffeine compared to only 12 reps after placebo. Despite completing more work during the caffeine trial, muscle soreness 2 and 3 days after exercise was significantly reduced compared to placebo. Caffeine was also associated with a significantly lower rating of perceived exertion during exercise. Reduces exercise pain perception
A common finding in many caffeine and exercise studies is the perception that exercise
is easier when taking caffeine, which was confirmed in a recent experiment designed to show the effects of caffeine on perceived pain during a task that elicited discomfort. Healthy college students performed a grip task that consisted of holding on to a metal block with their arm extended. They were instructed to resist dropping the weight. During one trial they chewed gum containing caffeine and during another identical trial they were provided gum with no caffeine. Subjects were able to hold on to the metal for an average of about 100 seconds, during which time they rated the level of pain to be significantly less during the caffeine (3.5) versus the placebo (4.8) trial (0 = no pain, 5 = moderate pain, 10 = worst possible pain). Caffeine mildly speeds caloric and fat burning at rest and during exercise
Several studies have shown that caffeine ingestion mildly increases caloric expenditure (aka, thermogenesis) on the order of about 10% for the few hours after ingestion. What’s more interesting is that caffeine intake specifically doubles fat turnover and increases fat burning by 24%. Caffeine intake also increases the use of fat during exercise, an effect that is associated with significant sparing of muscle glycogen and improved endurance performance. Less weight gain over 12 years
In a massive study that followed nearly 60,000 adults over a 12 year period, it was found that people who increased their caffeine intake the most had less weight gain than those who decreased caffeine intake, even after adjusting for energy intake. The effects were small, but are consistent with the known metabolic effects of caffeine. Used appropriately, caffeine is safe
In large systemic reviews, moderate coffee consumption is associated with reduced risk of type-2 diabetes9 and heart failure.10 There is also no evidence that moderate caffeine ingestion before exercise leads to dehydration, ion imbalance, or any other serious adverse effects.
A large range of caffeine doses have been studied, but most positive effects can be achieved with 100-200 mg, or less if combined with green tea. Effects vary from person to person so you may need to find the right dose that works for you. Caffeine levels peak 30–120 minutes after ingestion and thus it makes sense to consume it 30 to 60 minutes before exercise. Since caffeine is a stimulant, don’t use it before going to bed. Caffeine does result in a physical dependency, but not an addiction. Thus, if you are a regular caffeine user and you miss your morning cup of coffee, it is completely normal to experience mild withdrawal symptoms like headache and drowsiness. If you have high blood pressure, heart abnormalities, sleep disorders or any other medical condition, or if you are under the age of 18, you should check with your physician before using caffeine.