Caffeine in Athletics

By: Michelle Celie Drinkard

What is Caffeine?

How does it affect the body?

What about endurance?

How does it affect cognitive function?

What about sports drinks?

Are there any risks?

The diuretic effect

Other health concerns

More things to consider

Conclusion

Bibliography

What is Caffeine?

            The world’s most popular drug is legal, inexpensive, and believed to amplify workouts.  It supposedly motivates athletes and helps them stay alert and focused while also boosting physical endurance by twenty to fifty percent.  This stimulant is found naturally in sixty-three plants and is consumed by eighty percent of Americans.  This white, bitter, crystalline substance is known as caffeine, and is commonly consumed in efforts to enhance athletic ability (http://gopher1.bu.edu/COHIS/substance/caffeine/about.htm).

          Caffeine is a very popular stimulant among athletes because most believe that it provides energy, increases alertness, and quickens reaction time.  When in beverage form, caffeine reaches all body tissues within five minutes of ingestion.  However, peak blood levels are reached in thirty minutes.  Therefore, many cyclists consume a cup of coffee half an hour before short races begin.  Others drink a bottle of coke diluted with water during the last half of longer races (http://www.roble.net/marquis/caffeine).  The use of caffeine is controversial in the sports world, because it is a stimulant.  In fact, the UCI forbids drinking caffeine in large quantities prior to competitions.  But, why is there such a desire amongst athletes to consume this drug?  Are its results really that effective?  To answer these questions one must investigate how caffeine works.

 

How does it affect the body?

        The exact process by which it affects the body is unknown.  It is suspected that caffeine affects the nervous system by altering the perception of effort and exciting the neurons responsible for contracting muscles.  It may also be accountable for causing more fat and less carbohydrates to be burned.  Another source suggests that caffeine alters the levels of CNS neurotransmitters and metabolism of circulating free fatty acids.  The end result is an increase in blood sugar for use as muscle fuel.  Basically, it is believed that caffeine raises the general metabolism of the user, which resultantly increases the activity and raises the body’s temperature (wysiwyg://35/http://onhealth.com/ch1/indepth/item/item.34623_1_1.asp).

 

What about endurance?

          Various studies have been conducted in attempts to connect the use of caffeine with increased endurance levels.  Graham and Spriet (1995) conducted a double-blind test involving eight endurance runners.  Each participated in a control test previous to the study in which they ran a prescribed distance, to the point of exhaustion.  All ate similar meals and abstained for caffeinated substances previous to the trials.  Over a four-week period, each runner returned to the laboratory to run the prescribed distance while intravenously being given varying doses of caffeine.  A blood and oxygen sample was collected every fifteen minutes during the run in order to record the time span until physical exhaustion was reached.  The results confirmed that low doses of caffeine caused a drastic increase in endurance levels, while not altering the epinephrine (or adrenaline) levels.  Also, large doses of caffeine caused great increases in plasma epinephrine levels while only slightly altering the endurance levels.  This test, therefore, supposes that small doses of caffeine, when compared to placebo trials, are very beneficial in raising endurance capabilities.

          A very similar test by Pasman (1995) was conducted in which nine advanced cyclists were studied concerning their rate of time until exhaustion.  Each came in on a weekly basis at the same time and day of every week.  The cyclists were told to swallow a capsule that contained varying amounts of caffeine, though neither the cyclists nor the administrator knew the amounts the subjects received.  After an hour of rest, the cyclists were told to ride until exhaustion to measure endurance levels.  The results suggest that endurance increased with the consumption of small amounts of caffeine, when compared with placebo trials.   Surprisingly, no difference appeared between the varying amounts of caffeine in each capsule.

          With regard to short-term endurance, caffeine appears to have conflicting effects.  During a prolonged handgripping contraction test, caffeine appeared to improve muscular force production.  A review by Williams (1991) further supported this theory.  Cyclists were asked to ride to exhaustion.  Then, they were injected with caffeine during a twenty-minute resting period and once again subjected to the cycling.  Caffeine appeared to improve each following test by 22%.  However, in a 100-yard swimming test, subjects did not appear to benefit from ingesting various levels of caffeine when compared to the control groups.  This concludes that there are no clear connections between the effects of caffeine on short-term muscular endurance capabilities.  In four similar tests, contradicting evidence repeatedly appears.

The review of Dodd, Herb, and Powers (1993) draws the connection between human and animal receptiveness to caffeine.  In animal studies, large caffeine doses cause increased muscle contraction and what would be enhanced physical performance in humans.  However, the amount of caffeine necessary to make the same improvements in humans is not usually feasible and quite possibly toxic.

 

How does it affect cognitive function?

          To decipher whether caffeine is beneficial to athletic ability, one must also take into account its role on mental abilities.  Hogervorst (1999) conducted a double blind study on fifteen triathletes.  Each was subjected to visual and audible testing regarding Dutch vocabulary.  A word would appear on a computer screen and be pronounced.  At the end of fifteen minutes the athletes were asked to recall as many of the words, that they had just been taught, as was possible.  Before each trial, caffeine or a placebo was ingested on a randomized basis.  The results imply that caffeine causes increased cognitive function when compared to the control trials.  This effect is desired amongst athletes as quick reasoning is crucial in many instances.

What about sports drinks?

          Ferrauti (1997) reviewed the effects of caffeine in drink form on athletic performance.  Sixteen advanced tennis players participated in the study; each was fed standardized meals and no caffeine was consumed prior to testing.  Before and after each match blood and urine samples were collected with the intent of measuring the free fatty acids present in the system.  The results did not provide clear results regarding caffeine’s effect on athletic ability.  After consumption running speed was improved, though accuracy did not differ.

 

Are there any risks?

        Caffeine has many dangers involved in its consumption.  It is believed to lead to pancreatic or bladder cancer, elevate cholesterol levels, increase risk for heart disease and heart attack, and temporarily raise blood pressure.  More common side effects include nervousness, restlessness, anxiety, irritability, and aggravated premenstrual cycles in women.  Caffeine is also responsible for a greater excretion of calcium in urine, which makes bones more brittle and can eventually lead to osteoporosis (http://www.mayohealth.org/mayo/9707/htm/coffee.htm).

 

The Diuretic Effect

          The diuretic effect raises concerns with athletes concerned with long distances.  One would not want to lose a tri-athalon because he/she had to stop to urinate.  Tarnopolsky (1994) asserts that caffeine consumption does not affect sweat loss or plasma volume, therefore proclaiming that caffeine would not be detrimental to endurance athletes in way of urination or heatstroke.   The study involved five athletes running in unpleasantly hot and humid conditions for an hour at a time.  Each ingested different amounts of caffeine with varying trials.

          In a similar study, Wemple (1997) asserts that caffeine does not increase the loss of bodily fluid during exercise.  Six athletes participated in a preliminary physical exertion test so that a control would be set for each individual.  In following weeks all consumed foods similar to those that would be eaten prior to any athletic competition and caffeine was restricted.  On testing days each entered the lab and ingested a randomized amount of caffeine on a double-blind basis.  The subjects then waited in humidified rooms for fifteen minutes before physical exertions were again tested, followed by blood, urine, and sweat samples.  Although caffeine does increase urine flow in at rest individuals, it had no effect on individuals engaged in exercise.  This suggests that athletes should not be concerned with caffeine causing a need to urinate any more than any other beverage.

Other Health Concerns

          Perhaps one of the most startling risks involved with caffeine is the risk of a raised blood pressure.  Kaminsky (1998) shows the relationship between caffeine ingestion prior to physical activity and its effect on blood pressure.  Eighteen men were chosen to take part in a study where all consumed varying levels of caffeinated beverages, with the chance of receiving a placebo.  The drinks were administered on a double-blind basis.  Following the consumption, the men were asked to remain at rest and at later trials to perform various degrees of physical exertion.  The results prove that caffeine raises both diastolic and systolic blood pressure when at rest.  Also, caffeine heightened the systolic blood pressure at every level of activity, whereas it only raised the diastolic blood pressure at the greatest level of exertion. 

          Another severe effect of caffeine is the possibility of its delaying one’s conception capabilities.  Hatch and Bracken (1993) chose 1909 women out of a beginning group of 4186 women on the basis of their being married to their first husbands, over the age of eighteen, pregnant, and having conceived while not on a form of birth control.  This retrospective study divided the women up into two groups determined by the amount of time it took them to conceive after they stopped taking birth control.  These groups were asked various questions regarding their caffeine consumption on a daily basis.  The results did not suggest a correlation between caffeine intake and infertility.  However, when pared with smoking, caffeine consumption resulted in delayed conception.

 

More things to consider

          Caffeine is classically addictive.  Regular users develop tolerance towards it and thus, require more to obtain the expected effect.  Withdrawal symptoms usually include headache for several days and possible constipation (http://www.healthyideas.com/healing/herb/coffee.html).  The United States Food and Drug Administration and the American Medical Association profess the safety of caffeine.  However, both the Canadian and the United States governments advise pregnant women to restrict their caffeine intake.  Pregnant women who consume three cups of coffee a day have a greater chance of miscarriage than those who do not (http://gopher1.bu.edu/COHIS/subsabse/caffeine/sympsign.htm).  There is bitter dispute between caffeinated product manufacturers and natural remedy advocates over the benefits and consequences of caffeine.  Manufacturers appeal to the public, particularly athletes, on the professions of increased alertness.  Contrastingly, herbal advocates point out the sometimes-drastic side effects of this popular stimulant.

 

Conclusion

        In conclusion, caffeine does appear to improve long-term physical endurance when ingested in various amount.  However, no clear connection between caffeine consumption and short-term endurance has been drawn.  The diuretic effects of caffeine do not appear to pose a problem to athletes, though caffeine at rest does cause increased urination.  The risks involved with caffeine range from elevated blood pressure to delayed conception ability.  These factors should be carefully considered before caffeine is embraced in one’s lifestyle.


Bibliography

Dodd, Herb, and Powers (1993) Caffeine and exercise performance. Sports Medicine, 15, 14-23.

 

Ferrauti, Weber, and Struder (1997) Metabolic and ergogenic effects of carbohydrate and caffeine beverages in tennis.  Journal of Sports Medicine and        Physical Fitness, 37, 258-66.

 

Graham and Spriet (1995) Metabolic, catecholamine, and exercise performance responses to various doses of caffeine.  Journal of Applied Physiology,      78, 867-74.

 

Hatch and Bracken (1993) Association of delayed conception with caffeine consumption.  American Journal of Epidemiology, 140, 663-5.

 

Hogervorst, Riedel, Kovacs, Brouns, and Joulles (1999) Caffeine improves cognitive performance after strenuous physical exercise.  International         Journal of Sports Medicine, 20, 354-61.

 

Kaminsky, Martin, and Whaley (1998) Caffeine consumption habits do   not influence the exercise blood pressure response following caffeine    ingestion.  Journal of Sports Medicine and Physical Fitness, 38, 53-8.

 

Pasman, van Baak, Jeukendrup, and de Haan (1995)  The effect of different dosages of caffeine on endurance performance time.  International      Journal of Sports Medicine, 16, 225-30.

 

Tarnolpolsky (1994)  Caffeine and endurance performance.  Sports Medicine, 18, 109-25.

 

Wemple, Lamb, and McKeever (1997)  Caffeine vs caffeine-free sports drinks: effects on urine production at rest and during prolonged exercise.          International Journal of Sports Medicine, 18, 40-6.

 

William (1991)  Caffeine, neuromuscular function and high-intensity exercise performance.  Journal of Sports Medicine and Physical Fitness, 31, 481-        9.

 

 

 

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