The Effects of Caffeine on Performance in Sports
Dr Larry W. McDaniel Ed.D., Kyle McIntire, Carmyn Streitz, Allen Jackson, MS. Laura Gaudet Ph.D. discuss critical issues related to the effects of caffeine on athlete's performance.
Athletes who use caffeine before exercising or competition may be helping themselves more than they think. Caffeine is classified as a stimulant and is the most common drug used in the world. Caffeine has the same effects that amphetamines and cocaine have, just to a lesser degree. Caffeine crosses the membranes of all the body's tissues. It can wield effects on the central nervous system and the peripheral tissues that result in physiological effects. Studies have shown that caffeine can help an athlete perform better in a variety of different activities. It is a powerful ergogenic aid that is beneficial for athletic performance and training. Caffeine has been shown to increase speed and power output, improve the length an athlete can train, and assist the athlete in resisting fatigue. Caffeine has also been proven to stimulate the brain, which contributes to an athlete's clearer thinking and ability to concentrate harder on the task at hand. Studies have shown that up to 25% of athletes ages 11-18 years old have used caffeine to improve their athletic performances. Because of caffeine's effect on the body and its ability to increase an athlete's performance Olympic Committees have debated on whether caffeine should be tested before the Olympic Games.
The purpose of this paper is to explore caffeine's effect on athletic performance. An additional focus will be to search for information related to the benefits of caffeine that may improve, performance.
Need for Study
"Caffeine is classified as a stimulant and is performance-enhancing (Jenkinson & Harbert, 2008, pg. 3)". Caffeine is the most commonly used drug. In general, society would not approve of an athlete using a steroid drug or a stimulant, but no one reacts negatively to athletes drinking coffee, tea, energy drinks, or pop. Caffeine is appearing in many other products, including energy drinks and bars, sports gel, alcoholic beverages, and diet aids.
Figure 1 shows a comparison of caffeinated drinks, many of which are used by athletes before a competition.
The American Alliance for Health stated that there are three ways that caffeine may provide ergogenic effects. "First, the metabolic theory suggests that caffeine provides improved endurance due to increased utilization of fat as fuel and a sparing effect on carbohydrate utilization. Secondly, caffeine may increase the calcium content of skeletal muscle and enhance the strength of muscle contraction. Lastly, caffeine has a direct effect on the central nervous system as a stimulant, and this can help with fatigue, increased alertness, and increased muscle recruitment (Powers M, 2004, pg. 4)".
Many athletes have used caffeine before competitions for years, but it wasn't until recently that caffeine has been discovered to aid an athlete's performance. "Results of studies reported over the last five years strongly indicate that caffeine effectively increases athletic performances in endurance events (Sinclair & Geiger, 2000, pg. 2)". Athletes ranging from long-distance runners to those participating in strength and power competitions benefit from caffeine consumption. "Persons were able to complete a cycling time trial significantly faster after caffeine ingestion, and 2,000-meter rowing time was reduced by 1.2% after caffeine ingestion (Jenkinson & Harbert, 2008, pg. 3)". Figure 2, found in Appendix 1, shows the effects that caffeine has on endurance performance. Caffeine is a common substance found in the diets of many athletes; therefore, it is essential to study the impact on the athletes' body. "Caffeine operates using the same mechanisms that amphetamines and cocaine use to stimulate the brain; however, the effects are milder. Because it crosses the membranes of all tissues in the body (Powers M, 2004, pg. 4)".
Caffeine is a powerful ergogenic aid that may be beneficial in training and athletic performance. "It can exert its effects on both the central nervous system and the peripheral tissues, resulting in several physiological effects that might improve performance (Powers M, 2004, pg. 4)". Caffeine has been shown to increase speed and power. It also allows athletes to train longer. Caffeine stimulates the brain, which contributes to clearer thinking and higher concentration. Studies have shown that caffeine does not directly improve maximal oxygen capacity but assists in the process of resisting fatigue. "Although the effectiveness of caffeine as a means of masking fatigue has been explored since the early 1900s, the use of this ergogenic aid became popular following widely publicized research indicating improved endurance performance (Applegate & Grivetti, 1997, pg. 6)". Like all drugs, caffeine use has some side effects. No evidence states that caffeine leads to dehydration, ion imbalance, or any other adverse effects.
Summary of Findings
"Caffeine is the most widely ingested psychoactive drug in the world (Sinclair & Geiger, 2000, pg. 1)". Caffeine can lead to dependence, tolerance, drug craving, and withdrawal symptoms when it is used chronically. However, it is still a legal substance used in sports. This stimulant is known to assist athletes in training harder and longer. "Drug use among athletes to achieve athletic benefit starts at a very young age. Of 11 to 18-year-old students surveyed, 35% believed caffeine could enhance performance, and 25% used caffeine to increase athletic performance (Sinclair & Geiger, 2000, pg. 2)".
The stimulant caffeine affects the brain, which contributes to clearer thinking and higher concentration. The purpose of this study was to investigate the effects caffeine has on athletic performance. An article published in the American Alliance for Health, Physical Education, and Recreation (2004) stated that "There appear to be three primary mechanisms by which caffeine might provide an ergogenic effect. First, the metabolic theory suggests that caffeine provides improved endurance due to increased utilization of fat as a fuel and a sparing effect on carbohydrate utilization. Secondly, caffeine may increase the calcium content of skeletal muscle and enhance the strength of muscle contraction. Finally, caffeine has direct effects on the central nervous system as a stimulant which may alter the perception of fatigue, increase alertness, and increase muscle recruitment. An endurance athlete may be more likely to consider using the first mechanism. In contrast, the latter two would more likely be used by athletes participating in strength and power competitions and events requiring arousal and alertness (Powers M, 2004, pg. 4)".
Caffeine may be absorbed in several different ways and can be administered orally, through injections administered either subcutaneously or intramuscularly, or by suppositories. "The actions of caffeine throughout the body correlate positively with caffeine levels, and the levels are governed by caffeine absorption, metabolism and excretion. Caffeine is absorbed efficiently through the gastrointestinal tract after oral administration with about 100% bioavailability (Sinclair & Geiger, 2000, pg. 2)".
Speed/Power in Long-Term Exercise
There have been few studies conducted to evaluate the effects caffeine has on speed or endurance event. Early studies found improvements in activities such as repeated jumping, bench stepping, cycling, and treadmill tests. Researchers have studied elite skiers on a 20-23 km course at both high and low altitude. The ingestion of caffeine resulted in faster performance times at the halfway mark and the finish line. The total time was about 55-67 minutes, while caffeine resulted in times of 33 and 101 seconds faster for low and high altitudes.
Another study explained an individual who performed 2 hours of cycle exercise after caffeine ingestion. The caffeinated athletes generated 7.3% greater total power output. Skilled cyclists were told to perform, as quickly as possible, a set amount of work that was estimated to take about an hour. After exercising to exhaustion, seven endurance cyclists were given either a straight carbohydrate drink or one laced with the equivalent of six cups of coffee. "While it's been established that carbohydrates and caffeine improve a variety of athletic performances, this is the first study that has revealed that combining caffeine with carbohydrates after you have exercised can help your muscles refuel more rapidly (Caffeine Aids Athlete Recovery, 2008, pg. 1)". When the solution contained caffeine, the power output improvement was higher.
Endurance in Short-Term, Intense Exercise
Endurance in short, intense exercise is difficult to measure, therefore has received less attention. One study showed that exercise resulted in rapid exhaustion within 6 minutes, and caffeine did not affect. Two other studies demonstrated participants exercising for 15 to 20 minutes had a small increase in endurance (0.3 to 0.5 minutes) after consuming caffeine. Caffeine either has positive effects or causes no significant improvement to short-term, intense exercise.
Power in Short-Term, Intense Exercise
The ability to perform at high-intensity has been examined in several studies. In an additional study, participants simulated a 1500m run, and coffee ingestion produced a 4.2 seconds improvement in running speed. Dr Collomp studied swimmers who swam 100m freestyle. Caffeine ingestion significantly improved the meantime of highly trained simmers by about 1 second, while untrained athletes showed no improvement. When activities of shorter duration are examined, the results are more inconsistent, probably because the potential gain is small and difficult to measure. These areas are not well studied, but it appears exercise lasting at least 60 seconds proves caffeine as an ergogenic aid and no studies are showing negative effects.
It has been found that caffeine results in glycogen sparing. Professor John Hawley, Head of RMIT's Exercise Metabolism Group, found that athletes who had caffeine with their meal after exercise had 66% more glycogen in their muscles 4 hours later (Caffeine Aids Athlete Recovery, 2008). Glycogen is the body's preferred fuel for muscles when exercising. Hawley Stated, "If you have 66% more fuel for the next day's training or competition, there's no question you will be able to go further and faster (Caffeine Aids Athlete Recovery, 2008, pg. 1)". Many experiments are lasting less than 30 minutes in which caffeine is beneficial when glycogen does not appear to be limiting.
Caffeine is a complex substance that is found in many organic compounds and is consumed by humans in coffee, tea, and chocolate. Caffeine is the most commonly used drug in the world. Food industries are adding caffeine to a wide variety of foods and drinks. Caffeine is found in many 'natural health products' and many over-the-counter drugs. The effect caffeine has on the body ranges from various adenosine receptors in several types of body tissues.
Caffeine is ergogenic in most if not all aerobic exercises. Studies have shown that as an ergogenic aid caffeine enhances endurance-type exercises such as running, swimming, cycling, and tennis. Studies have shown that caffeine also provides benefits in anaerobic activities such as resistance training. Olympic committees are debating whether or not caffeine should be tested before the Olympic Games because of its ergogenic effects. "Glucose recovery slows drastically after 3-4 hours, so recovery rates after 4 hours are excellent proxies for glycogen storage 24 hours after exercise. If you have 66% more fuel for the next day's training or competition, there's no question you will be able to go further and faster (Caffeine Aids Athlete Recovery, 2008, pg. 1)".
So far, there has been little evidence demonstrating that the administration of caffeine substances before or after exercise produces a negative effect. One article stated, "The mechanisms involved in the actions of these compounds are varied and complex and extend well beyond the traditional explanation of sparing of muscle glycogen to involve fundamental aspects of muscle contractility probably." Many scientists have conducted several tests and experiments to determine caffeine's effects and will continue researching caffeine as an ergogenic aid.
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About the Authors
Larry W. McDaniel Ed.D. is an Associate Professor of Exercise Science at Dakota State University Madison, SD. USA. Dr McDaniel was a First Team All-American football player (USA Football), a Hall of Fame Athlete, and Hall of Fame Wrestling Coach.
Allen Jackson, M. Ed. is an Assistant Professor of Physical Education and Health at Chadron State College in Chadron, Nebraska (USA) who is well known for his presentations and publications at international conferences focusing on Leadership, Curriculum, and Health.
Laura Gaudet, Ph.D. is a Professor and Chair of the Department of Counselling, Psychology, and Social Work at Chadron State College, Chadron NE.
Dr Gaudet is well known for her publications and presentations at international conferences focusing on various topics in the field of psychology.
Kyle McIntire & Carmyn Streitz Dakota State University are outstanding athletes and students of Exercise Science.