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Studies Show Coffee Before a Workout May Increase Your Endurance

Coffee is ingrained in many people’s early morning routines because they rely on its mildly stimulating effect to get them going for the day. In addition to keeping people from crawling back to bed and eluding their responsibilities in the morning, the world’s favorite hot beverage can also help people power through long grueling workouts, according to new research published in the International Journal of Sport Nutrition and Exercise Metabolism.

Although endurance athletes commonly ingest caffeine in the form of powder or tablets as a means to enhance training intensity and competitive performance, conflicting evidence exists regarding the efficacy of coffee — a popular source of caffeine — in improving athletic performance. Unsure of coffee’s effect on performance, researchers conducted a meta-analysis review to evaluate how pre-exercise coffee impacts endurance performance.

“There’s a perception that coffee won’t give you the same benefits as pure caffeine,” study lead author Simon Higgins said in a statement. “New research could mean that athletes could have a cup of coffee versus taking a pill.”

Caffeine, the most popular psychoactive substance among people of all age groups and cultural backgrounds, is typically used to boost the central nervous system for cognitive or physical endeavors. The stimulant is produced by a variety of beans, leaves, and fruits, but is most commonly consumed in the form of coffee, according to the National Council on Strength and Fitness (NCSF).

For the study, Higgins and his colleagues reviewed nine randomized control trials that specifically used coffee to improve endurance. During the trials, study participants either cycled or ran after drinking coffee. They then exercised vigorously, and the results were measured.

Researchers from five studies found significant improvements in endurance performance. They found between 3 and 7 milligrams per kilogram of body weight of caffeine from coffee increased endurance performance by an average of 24 percent. The amount of caffeine in a cup of coffee can vary from 75 milligrams to more than 150, depending on the variety and how it’s roasted and brewed. Americans consume about 27 ounces of coffee each day, Medical News Today reported.

“This is helpful for athletes because coffee is a naturally occurring compound,” Higgins said. “There’s the potential that getting your caffeine by drinking coffee has similar endurance benefits as taking caffeine pills.”

Previous studies have linked coffee to many health benefits, including a reduced risk of dying from cardiovascular disease, an extended lifespan, and a lower risk of developing type 2 diabetes.

Higgins said the endurance effects of coffee as a source of caffeine could be just as advantageous as taking caffeine in the form of powder or tablets.

“While there is a lack of high-quality research on coffee as a source of caffeine, there is an abundance of research on pure caffeine,” he said. “It’s surprising how little we know about caffeine from coffee when its endurance effects could be just as beneficial as pure caffeine.”

Nevertheless, before any recommendations can be given to athletes, more research will be needed to determine how different the effects of caffeine from coffee are against those from pure caffeine — especially since the amount of caffeine in a cup of coffee can vary.

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Give Your Workout a Rush

Half of Americans start their day with coffee, and according to recent study, working out after downing a cup of java may offer a weight-loss advantage.

The Spanish study, published in the International Journal of Sport Nutrition and Exercise Metabolism, found that trained athletes who took in caffeine pre-exercise burned about 15% more calories for three hours, post-exercise, compared to those who ingested a placebo. The dose that triggered the effect was 4.5 mg of caffeine per kilogram of body weight. For 150-pound woman, that’s roughly 300 mg of caffeine, the amount in about 12 ounces of brewed coffee, a quantity you may already be sipping each morning.

If you’ve always thought of coffee as a vice—one you’re simply not willing to give up—you’ll be happy to know that it’s actually a secret superfood. And if you exercise, caffeine can offer even more functional benefits for your workouts.

The Skinny on Caffeine

“Caffeine is a stimulant that acts on the central nervous system, the heart, and possibly the ‘center’ that controls blood pressure,” all of which play a vital role in helping your mind and body push harder in a workout, says Heidi Skolnik, M.S., a sports nutritionist and owner of Nutrition Conditioning, Inc. “It can also increase the release of feel-good neurotransmitters like dopamine, which effects pain receptors and mood” while you’re working out.

In other words, you’ll actually enjoy getting sweaty and it will feel easier when you’re powering through those last few reps. Plus, researchers found that when people caffeinated before a workout, they ate 72 fewer calories later in the day and had an easier time keeping cravings in check. Not a bad deal.

Here are six more reasons to enjoy it as part of an active lifestyle:

(1) Improved Circulation

Recent Japanese research studied the effects of coffee on circulation in people who were not regular coffee drinkers. Each participant drank a 5-ounce cup of either regular or decaffeinated coffee. Afterward, scientists gauged finger blood flow, a measure of how well the body’s smaller blood vessels work.

Those who downed “regular” (caffeinated) coffee experienced a 30% increase in blood flow over a 75-minute period, compared to those who drank the “unleaded” (decaf) version. Better circulation, better workout—your muscles need oxygen!

(2) Less Pain

Scientists at the University of Illinois found that consuming the caffeine equivalent of two to three cups of coffee one hour before a 30-minute bout of high-intensity exercise reduced perceived muscle pain. The conclusion: caffeine may help you push just a little bit harder during strength-training workouts, resulting in better improvements in muscle strength and/or endurance.

(3) Cognitive Performance

A study of 68 Navy Seal trainees—published in the journal Psychopharmacology—found that caffeine, in a dose-dependent manner, mitigated many adverse effects of exposure to multiple stressors. Caffeine (200 and 300 mg) significantly improved visual vigilance, choice reaction time, repeated acquisition, self reported fatigue and sleepiness, with the greatest effects on tests of vigilance, reaction time, and alertness. Marksmanship, a task that requires fine motor coordination and steadiness, was not affected by caffeine. The greatest effects of caffeine were present 1 h post-administration, but significant effects persisted for 8 h.

Even in the most adverse circumstances, moderate doses of caffeine can improve cognitive function, including vigilance, learning, memory, and mood state. When cognitive performance is critical and must be maintained during exposure to severe stress, administration of caffeine may provide a significant advantage. A dose of 200 mg appears to be optimal under such conditions.

(4) Burn More Fat

Caffeine stimulates the nervous system, which sends direct signals to the fat cells to tell them to break down fat. Another thing that caffeine does is to increase our blood levels of the hormone Epinephrine, which is also known as Adrenaline. Epinephrine travels through the blood, to the fat tissues and send signals to break down fats and release them into the blood.

This is how caffeine helps to mobilize fat from the fat tissues, making it available for use as free fatty acids in the blood.

(5) Muscle Preservation

In an animal study, sports scientists at Coventry University found that caffeine helped offset the loss of muscle strength that occurs with aging. The protective effects were seen in both the diaphragm, the primary muscle used for breathing, as well as skeletal muscle. The results indicate that in moderation, caffeine may help preserve overall fitness and reduce the risk of age-related injuries.

(6) More Muscle Fuel

A recent study published in the Journal of Applied Physiology found that a little caffeine post-exercise may also be beneficial, particularly for endurance athletes who perform day after day.

The research found that compared to consuming carbohydrates alone, a caffeine/carb combo resulted in a 66% increase in muscle glycogen four hours after intense, glycogen-depleting exercise. Glycogen, the form of carbohydrate that gets stockpiled in muscle, serves as a vital energy “piggy bank” during exercise, to power strength moves, and fuel endurance.

Moral of the story: caffeine makes your workout more fun and helps you push a little bit harder during your workouts and burning more fat. Cheers to that!

 


The effects of caffeine on upper and lower body strength

A recent Journal of Strength and Conditioning Research study evaluated the impact of caffeine on muscle mass. The reasoning behind the new study, is that caffeine’s impact on musculature may reach significance only in large muscle groups or when used over time. In long efforts like endurance training, caffeine is unanimously an ergogenic aid. However, in power and strength trials the effects are less clear.

If caffeine’s primary area of influence is the nervous system, then it stands to reason that muscles with a larger number of motor units will be more influenced by it.

The authors addressed this question and hoped to clear up some of the past confusion in the research.

Study Design

Sixteen recreationally trained young men participated in this study. They were chosen in part because none of them were heavy habitual caffeine consumers. On average they consumed 300mg of caffeine or less each day, which amounts to a couple cups of coffee.

During the test, each of the subjects consumed 6mg of caffeine per kilogram of bodyweight.For a 200lb man this would be about 540mg of caffeine. On a different occasion, they consumed a placebo instead. The order of the tests was randomized. Thirty minutes after caffeine ingestion, the maximum voluntary contraction of each participant was recorded for the quads, calves, biceps, and wrist flexors.

Results

Caffeine significantly improved peak torque for all of the muscle groups in the upper and lower body. Although the motor unit recruitment didn’t appear to be significant in the prior study mentioned above, in this new study it seemed to work even for the biceps and wrist flexors, which were the smallest of the studied muscles. There was a trend towards larger muscles gaining a greater benefit from the caffeine, but it did not reach significance.

The results for improvement when using caffeine over placebo were as follows, in order from largest muscle group to smallest.

  • Quads: 13.7%
  • Calves: 11.2%
  • Biceps: 9.1%
  • Wrist Flexors: 6.3%

Whatever the exact cause of the improvement in strength performance from caffeine ingestion, a small difference adds up the more muscle fibers you use.

References:

  1. Tomas Timmins, et. al., “Effect of Caffeine Ingestion on Maximal Voluntary Contraction Strength in Upper and Lower Body Muscle Groups,” Journal of Strength and Conditioning Research 2014, DOI: 10.1519/JSC.0000000000000447

 


The Effects of Caffeine on Performance in Sports

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 affects that amphetamines and cocaine have, just in 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 has been shown to be a powerful ergogenic aid that is beneficial in 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 athlete’s ages 11-18 years old have used caffeine in effort to increase 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.

Purpose

The purpose of this paper is to explore caffeine’s affect on athletic performance. An additional focus will be to search for information related to the benefits of caffeine that may improvement performance.

Need For Study

“Caffeine is classified as a stimulant and is performance enhancing (Jenkinson & Harbert, 2008, pg. 3)[7]“. 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 a number of 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. Screen Shot 2016-07-14 at 2.30.45 PM

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 an 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)[9]“.

Many athletes have used caffeine prior to 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)[10]“. 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 percent after caffeine ingestion (Jenkinson & Harbert, 2008, pg. 3)[7]“. Figure 2, found in Appendix 1, shows the effects that caffeine has on the endurance performance. Caffeine is a common substance found in the diets of many athletes therefore it is important to study the effects 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)[9]“.

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 a number of physiological effects that might improve performance (Powers M, 2004, pg. 4)[9]“. 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 greater concentration. Studies have shown that caffeine doesn’t 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)[2]“. Like all drugs, caffeine use has some side effects. There is no evidence that 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)[10]“. 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 to train harder and longer. “Drug use among athletes for the purpose of achieving athletic benefit starts at a very young age. Of 11-18 year-old students surveyed, 35% believed caffeine could enhance performance and 25% used caffeine in an effort to increase athletic performance (Sinclair & Geiger, 2000, pg. 2)[10]“.

The stimulant caffeine affects the brain which contributes to clearer thinking and greater 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 an 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, while 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)[9]“.

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)[10]“.

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 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’ve exercised can actually help your muscles refuel more rapidly (Caffeine Aids Athlete Recovery, 2008, pg. 1)[4]“. When the solution contained caffeine the power output improvement was greater.

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 had no effect. 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 second improvement in running speed. Dr. Collomp studied swimmers who swam 100m freestyle. Caffeine ingestion significantly improved the mean time 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 improvement 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 there are no studies showing negative effects.

Muscle Glycogen

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)[4]. 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’ll be able to go further and faster (Caffeine Aids Athlete Recovery, 2008, pg. 1)[4]“. There are many experiments lasting less than 30 minutes in which caffeine has been shown to be beneficial when glycogen does not appear to be limiting.

Conclusion

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 a number of ‘natural health products’ and in many over-the-counter drugs. The affect 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 provide benefits in anaerobic activities such as resistance training. Olympic committees are debating whether or not caffeine should be tested prior to 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’ll be able to go further and faster (Caffeine Aids Athlete Recovery, 2008, pg. 1)[4]“.

So far there has been little evidence demonstrating that the administration of caffeine substances prior to or after exercise produces a negative effect. One article stated, “The mechanisms involved in actions of these compounds are varied and complex and extend well beyond the traditional explanation of sparing of muscle glycogen to probably involve fundamental aspects of muscle contractility.” Many scientists have conducted a number of tests and experiments to determine caffeine’s effects and will continue researching caffeine as an ergogenic aid.

References

  1. ANTONIO, J. (2004) Caffeine: The Forgotten Ergogenic Aid. Strength and Conditioning Journal, 26 (6), p. 50-51
  2. APPLEGATE, E. & GRIVETTI, L. (1997) Search for the competitive edge: A History of dietary fads and supplements. The Journal of Nutrition: 1996 ASNS Symposium Proceedings, 127 (5), p. 869-873
  3. BEAVEN, C. et al. (2008) Dose Effect of Caffeine on Testosterone and Cortisol Responses to Resistance Exercise. International Journal of Sport Nutrition & Exercise Metabolism, 18 (2), p. 131-141
  4. Caffeine Aids Athlete Recovery (2008) Australasian Science 1 Sep. 2008: ProQuest Education Journals. ProQuest. Karl E. Mundt Library, Madison, SD. 29 Jan. 2009 http://www.proquest.com/
  5. CLARK, N. (2005) Caffeine and Performance. Palaestra 1 Oct. 2005: 46. Research Library. ProQuest. Karl E. Mundt Library, Madison
  6. GRAHAM, T. (2001) Caffeine and Exercise: Metabolism, Endurance and Performance. Sports Medicine 31 (11), p. 785-807.
  7. JENKINSON, D. & HARBERT, A. (2008). Supplements and Sports. American Family Physician, 78 (9), p. 1039-1046.
  8. McNAUGHTON, L. et al. (2008). The effects of caffeine ingestion on time trial cycling performance. Journal of Sports Medicine and Physical Fitness, 48 (3), p. 320-325.
  9. POWERS, M. (2004) “Safety, Efficacy, and Legal Issues Related to DIETARY SUPPLEMENTS”, Strategies, 18 (1), p. 30-34.
  10. SINCLAIR, C. & GEIGER, J. (2000) Caffeine use in sports: A pharmacological review. Journal of Sports Medicine and Physical Fitness, 40 (1), p. 71-79.
  11. WALLACE, S. (2006) A Comparison of Caffeinated Drinks [Photograph] [WWW] Available from: http://biolife.files.wordpress.com/2008/04/caffeinated-drink-comparison.jpg [Accessed December 4,2009]

Click here to view this study online.

 


Strength activity from caffeine consumption

It is anecdotally reported that many strength athletes use caffeine to increase their performance. It is not clear whether the perception of improvement is related to maximum strength or power or to the rate of fatigue. This is an area where there is a distinct paucity of quality work. There have been studies[85-87] with humans that suggested that caffeine enhances myoneural function and contractility. Supinski et al.[87] reported that caffeine increased diaphragm contractility by 48%. Lopes et al.,[88] who studied the adductor pollicis in a small group (n = 5), stimulated the ulnar nerve at 10 to 100Hz and found no difference in maximum tension following ingestion of caffeine 500mg.

However, during low frequency stimulation there was an increase in submaximal tension – the frequency-force curve was shifted to the left. Kalmar and Cafarelli[89] performed a detailed study recently and found that caffeine increased maximal voluntary activation: maximal voluntary contraction (MVC) increased 3.5% and the time to fatigue at 50% MVC improved by 26%. They proposed that caffeine altered neural function at supraspinal and/or excitation-contraction sites, but not at the level of the spinal cord or neuromuscular junction. In 1989, Tarnopolsky et al.[90] measured a number of neuromuscular factors in endurance athletes before and after a 90-minute treadmill run. When the athletes had consumed caffeine, there were no measurable effects on MVC, peak twitch torque, motor unit activation, or half relaxation time. However, the investigators recently[61] revisited the issue with more sensitive methods. During 2 minutes of tetanic stimulation, caffeine ingestion resulted in increased force development during low, but not during high frequency stimulation. The researchers concluded that the enhanced contractility was caused by local actions on the muscle itself and probably involved excitationcontraction mechanisms (possibly calcium release via the ryanodine receptor).

This aspect of study is in its infancy, but is promising. It suggests that caffeine has direct actions on muscle and that these are independent of metabolic issues. Such studies not only reveal insight regarding possible beneficial effects of caffeine for strength athletes, but also give valuable information regarding possible sites of fatigue and mechanisms of caffeine action.


Speed / power in long-term endurance

Rarely have studies been conducted to evaluate the impact of caffeine on speed or performance in an endurance event (see table III). The author, having failed in attempting this because of factors including small sample sizes and changing environmental conditions, can appreciate the difficulties in conducting a quality study of this sort. Early studies[11,12,78-80] frequently found improvements in activities such as repeated jumping and bench stepping, as well as cycle and treadmill tests. These studies were frequently conducted with small groups and with protocol designs that are not acceptable today.

Cohen et al.[43] failed to show a benefit of caffeine ingestion in a small group who ran 21km in a hot, humid environment. In contrast, Berglund and Hemmingsson[44] found that caffeine did increase the speed of high quality, cross-country skiers in a competitive setting. This study has been criticized because the investigators normalized their data in a complex way. However, any field test is difficult, and skiing is a particularly thankless challenge given how snow conditions can change moment to moment, let alone day to day. To the author’s knowledge, this is the only investigation of caffeine ingestion to use elite athletes and to simulate a competition. The researchers studied elite skiers on a 20 to 23km course, both at low and high altitude. They found that, both at the halfway mark and finish, caffeine ingestion resulted in faster performance times. The total time was about 55 to 67 minutes and caffeine resulted in the halfway times being 33 and 101 seconds faster for low and high altitude, respectively. Similarly, finishing times were 59 and 152 seconds faster [all results were significant except for the finish time at low altitude (p < 0.10)].

Ivy et al.[42] had individuals perform 2 hours of cycle exercise and, after caffeine ingestion, the participants generated a 7.3% greater total power output. Similarly, MacIntosh and Wright[45] found that caffeine ingestion reduced the time for completion of a 1500m swim by 23 seconds. In perhaps the most controlled study, Kovacs et al.[31] approximated a cycle time trial. Skilled cyclists were told they had to perform, as quickly as possible, a set amount of work that was estimated to be approximately that of a 1-hour time trial. Ingestion of a carbohydrate/electrolyte solution during this activity tended to be beneficial and, when the solution also contained caffeine, the power output improvement was significantly greater (i.e., performance time was faster).


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