Coffee contains probably the most commonly used behaviour-altering substance in the world, caffeine.  It is consumed daily by millions of people all over the world including athletes who drink it for pleasure and consume it to reduce the pain.  There have been many articles written on its purported benefits and risks and much research has now been carried out into how it affects us.

What is Caffeine?

Caffeine is a fat-soluble compound belonging to a group called purines found naturally in 63 species of plants including coffee, tea and cocoa.

The intestines absorb caffeine readily, with peak concentration reached within 1 hour after consumption.  It is cleared from the blood by the liver taking about 3 to 6 hours to reduce blood caffeine concentrations by about half.  However, significant amounts can also be lost through sweat.

Are there any benefits to using caffeine as a sports supplement or ergogenic aid?

An ergogenic aid is any external influence that can positively affect mental or physical performance.  Caffeine has long been believed to provide such an influence over performance during exercise.

Numerous studies have been carried out on the use of caffeine in exercise covering most endurance sports including running, cycling and swimming.  The good news is that we know much more about what it can do, although the ‘why’ is still not entirely clear.  The bad news is that some of the research is conflicting.  For example, some studies say that withdrawal from caffeine for 2-4 days has no effect on performance (Van Soeren M. H. 1998) while others state the opposite (Dodd S. L. 1991)

The reasons why there are such variances in results of caffeine research include: dosage of caffeine, fitness level of subjects, prior nutrition, habitual level of consumption and, most importantly, type and duration of exercise.

However, generally studies have shown that ingesting the equivalent of 2.5 cups of fresh coffee or around 300-400mg of caffeine 1 hour before exercise extends endurance in strenuous aerobic exercise as well as improving higher intensity, shorter duration effort.  Studies have shown 10-20% improvements in performance in time to exhaustion at intensities around 85% VO2Max. 

As early as the 70s research had shown that caffeine taken 1hr before exercise increases plasma fatty acid concentrations (Costill D. L. 1978) leading to a suppression of carbohydrate metabolism and consequently to decreased glycogen utilisation.  This is great news for endurance athletes to assist in burning fat as a primary fuel source.  In most studies, caffeine also decreased perceived ratings of exertion – i.e. the same exercise felt easier with caffeine.

Caffeine can also help with efforts at 100%VO2Max though not from glycogen sparing. It may assist with muscle fibre recruitment, increasing the number of fibres recruited, muscle ion handling or enhanced aerobic energy production.

The ergogenic effects on endurance of caffeine occur less when taken in the form of coffee than for an equivalent dose taken in the form of a capsule in water (Graham T E 1998).  Components in coffee appear to inhibit caffeine’s action.  Additionally, beneficial effects do not consistently occur among habitual caffeine users (Van Soeren MH 1994).  Therefore, the athlete must consider tolerance of caffeine as a factor before deciding to use it as an ergogenic aid.

As well as acting as an ergogenic aid, caffeine has an effect on the functioning of the brain.  Studies have shown that it can improve attention, memory and concentration (Hogervorst 1999).

In Summary - The benefits for exercise

The majority of research on caffeine seems to agree in general that supplementing with caffeine prior to exercise:

· Increases time to exhaustion

· Increases fat metabolism in place of carbs

· Reduces perceived exertion

· Improves cognitive functioning

Is it or isn’t is a dieuretic?

Yes, and no! 

At rest, caffeine is a diuretic (i.e. it causes excess water to be lost through urine) and should not be consumed hours before exercise when hydration is required.

However, during exercise, the diuretic effect of caffeine is counteracted by catecholamines* causing constriction of renal arterioles (in the kidneys ) and reducing glomerular filtration rate.  The catecholamines possibly increase sodium and chloride reabsorption rates in the proximal and distal tubules by affecting aldosterone, an antidiuretic hormone.  Translated into English, this means that the net result is greater water retention and the supression of the dieuretic effect.  Caffeine has no effect on sweat rates.  Thus:

caffeine is a diuretic in resting conditions but not during exercise.

*Catecholamines are water-soluble and are 50% bound to plasma proteins, so they circulate in the bloodstream. The most abundant catecholamines are epinephrine (adrenaline), norepinephrine (noradrenaline) and dopamine.  They are hormones that are released by the adrenal glands in situations of stress such as psychological stress or low blood sugar levels, or during strenuous exercise.

Sources of Caffeine

The most common sources of caffeine for use as supplementation:

 

 

 

 

 

 

 

                

 

                 Source: Food labels

 

Guidance on using caffeine as an ergogenic aid

Firstly bear in mind the golden rule of sports nutrition:

If you plan to use ANY supplement, food or drink immediately prior to or during competition use it in training first.

Failure to do so could significantly reduce your ability to complete the competition, let alone compete.

You will need to experiment somewhat in training to find the right dosage for yourself based upon:

· Your normal intake of caffeine (those who have no normal intake will require significantly less to effect a response than those who drink 4 cups of coffee a day)

· Length and intensity of exercise.  Endurance athletes competing for more than 5 hrs will need to ‘top-up’ their blood caffeine levels  - but don’t over do it!)

· Heat and humidity.  Higher sweat rates may require increased intake.

You could start by experimenting with 2 espressos, then try three.

Take the coffee aprrox 1 hour before the start of the competition.

For competitions lasting several hours you should aim to top up your caffeine, depending upon conditions, by consuming around 2-3 caffeinated gels per hour or 2 cups of cola (de-fizzed).

General everyday use of caffeine

As caffeine is a dieuretic and a stimulant it is probably best avoided for athletes as a general everyday drink.  Caffeine is not an addictive substance although regular coffee drinking is habit forming.  Ironically, giving up caffeine can give you identical symptoms to consuming too much i.e. head aches, restlessness and nervous irritability.  These symptoms should pass within a few days then you will be free of them.

However, if you are a coffee lover and can restrict your habit to no more than 2 cups per day, the positive mental effect will probably outweigh any minor negative physical impact as long as you keep well hydrated.

The Dangers of Caffeine

Caffeine is a powerful stimulant of the Central Nervous System.  Individuals who normally avoid caffeine can suffer from various symptoms upon taking even small doses including:

Restlessness

Headaches

Nervous irritability

Muscle twitching

Elevated heart rate

Elevated blood pressure

Irregular heart beat

Normal use of caffeine posses no general health risk, however, overdose can kill.  The Lethal Oral Dose of caffeine is estimated at 10g (for a person weighing 67Kg) i.e. 150mg/Kg body mass.

Note: caffeine reduces the ergogenic effect of creatine supplementation on short-term muscular power (Vandenberge K 1996) and should therefore be avoided if the athlete is using creatine.

General Coffee Information

What is it?

Coffee comes from the roasted seeds (commonly referred to as beans) from the coffee plant, a small ever green bush or tree originally found in subtropical Africa and Asia.  Today it is also extensively farmed in Southern America and Hawaii, to the extent that Brazil is now the world’s largest producer and Colombia is the third largest (source: Food and Agricultural Organisation of the United Nations: Economics and Social Dept 2008).

How is it produced?

Generally the seeds are picked by hand.  The flesh is removed by machine and the seeds are fermented to remove an excess slimy layer of mucilage.  Once washed in large amounts of fresh water the ‘beans’ are dried, sorted and labelled as ‘green’ coffee beans.  The green coffee is then roasted at around 200 degrees celcius.

Decaffeination

Seeds are decaffeinated while they are still green, before roasting.  There are many methods used for this process, however, most of them involve either soaking the beans in hot water or steaming them, then using a solvent to dissolve the caffeine containing oils.  The extracted caffeine is then often sold to the pharmaceutical industry or used in soft drink manufacture.

Coffee Politics

There are a number of key issues with coffee production:

· The intensive farming of coffee, particularly in South America, has led to huge land clearing exercises (particularly rain forest) to make space for coffee plantations.

· Coffee growing and production requires a lot of water, yet is often grown in countries where there is a serious water shortage (i.e. Ethiopia the world’s fifth largest producer).

· A combination of a small number of very large buyers of coffee combined with the susceptibility to hugely varying harvests has caused significant problems for producers in the past.  The concept of ‘Fair Trade’ coffee was introduced to guarantee a negotiated pre-harvest price, however, this made up just 0.5% of worldwide coffee production in 2005 (source: Fairtrade Labelling Organisation 2009)

 

In January 2004 the IOC removed caffeine from its list of restricted substances.  Before then the IOC had set a tolerance limit as it was recognised that caffeine improves performance.

 

Associated Links:

www.fairtrade.net

 

References

Costill D. L., G. P. Dalsky, and W. J. Fink. “Effects of caffeine ingestion on metabolism and exercise performance.” Med Sci Sports Exerc, 1978: 155-158.

Dodd S. L., et al. “The effects of caffeine on graded exercise performance in naive versus habituated subjects.” Eur J Appl Physiol , 1991.

Graham T E, et al. “Metabolic and exercise endurance effects of coffee and caffeine ingestion.” (J Appl Physiol) 1998.

Hogervorst, E., W.J. Riedel, E. Kovacs, F. Brouns, and J. Jolles. “Caffeine Improves cognitive performance after strenuous physical exercise.” Int J Sports Med, 1999: 354-361.

Van Soeren M. H., and T. E. Graham. “Effect of caffeine of metabolism, exercise endurance, and catecholamine responses after withdrawl.” J Appl Physiol, 1998: 1493-1501.

Van Soeren MH, et al. “Caffeine metabolism and epinephrine responses during exercise in users and nonusers.” J Appl Physiol (J Appl Physiol ), 1994.

Vandenberge K, et al. “Caffeine counteracts the ergogenic action of creating loading.” J Appl Physiol, 1996.

 

 

 

COFFEE