NUTRITION


CAFFEINE


the amount of free fat y acids does seem to increase, there does not seem to be a concurrent sparing of carbohydrate stores. Another theory put forward to explain the positive eff ect that


caff eine has on performance stems from evidence that the drug can halt the build-up of potassium in an important area of the muscle, called the sarcoplasmic reticulum. Potassium build-up inhibits electrical activity in that muscle, resulting in a less effi cient movement during endurance exercise. Furthermore, scientifi c studies – and, I expect, your own experience – show caff eine increases feelings of wakefulness and this may counteract feelings of fatigue during long-distance events. Research also shows that perceived pain sensitivity and the rate of perceived exertion (how hard you feel that you are working at a given intensity) during exercise are reduced with caff eine ingestion. More recently, caff eine has been linked to the area of pain sensitivity in sport, suggesting that the drug can help to mask discomfort, although a review published in the last 12 months suggested that this eff ect may be psychological. This review included one study in which competitive cyclists were told that they would receive a placebo (low), 4.5mg/kg (medium) and 9mg/kg (high) dose of caff eine in three separate endurance cycling eff orts, whereas in fact they received a placebo in each trial. Improvements in power, as well as perceived pain sensitivity, arousal and fatigue were observed, as subjects believed they were receiving more caff eine. This fi nding – along with several other recent studies – shows that, while caff eine does appear to alter some physical parameters during exercise, positive results may be in part psychological. Furthermore, some scientists suggest that the negative eff ect of


knowing that you haven’t taken caff eine may be more damaging than the positive eff ect of taking it is benefi cial. In short, taking caff eine during exercise may work because the physical gains of taking it are boosted by the psychological benefi ts.


THE USE OF CAFFEINE DURING EXERCISE SEEMS TO BE A SAFE PRACTICE


FULL OF BEANS? Caff eine’s ability to enhance performance has been observed both in open-ended trials, where athletes perform a task to exhaustion, and close-ended trials, like time trials over a particular distance. However, while speed, peak power output, mean power output and time to exhaustion have all been shown to increase during endurance exercise under the infl uence of caff eine, there is limited data to show a similar improvement in sprint type or anaerobic activity. To maximise caff eine’s eff ect, a high dose of around 3-6mg per


kg of body weight should be ingested about 60 minutes before competition, as it takes this long for caff eine to peak in the system. This amount is most easily taken in a tablet or capsule form, as gels, drinks or bars may also include inappropriate amounts of carbohydrate or fl uid. If the type of exercise extends for a long period of time, then an additional amount, up to 1-2mg/kg can be taken every couple of hours. It takes the body around fi ve hours to reduce the amount of caff eine in the system by about half – this is known as caff eine’s half-life – so caff eine only needs to be topped up to continue to have its eff ect. Carbohydrate gels that contain 25-80mg of caff eine may be suitable for this task.


34


WHAT'S YOUR HIGH? Item


Coff ee (instant) Coff ee (Espresso) Black tea Green tea Chocolate (milk) Coke (Classic)


Serving Size Teaspoon


60ml 180ml 180ml 150g bar 1 can Monster Energy Drink 1 can Red Bull Pro Plus 1 can 1 tablet Power Bar Caff eine Gel 1 sachet ARE THERE ANY SIDE EFFECTS?


Despite some negative press, the use of caff eine – in day-to-day life as well as during exercise – seems to be a safe practice, although the eff ect of regularly ingesting caff eine on potential performance gains are unclear. For those who do not usually ingest high levels of caff eine, sudden intakes may act as a diuretic and cause the loss of body fl uid (which can increase the risk of dehydration). However, this fl uid loss does not seem to happen during exercise.


For this reason, non-habituated athletes should be careful not to include too much caff eine in their diet, especially aſt er exercise when rehydration is important. Aside from this, high doses may increase nervous tremors in non-habitual users, while low doses may cause headaches in habitual users, both of which are less than ideal. Also, ingesting caff eine in a natural form is diff erent to ingesting


caff einated supplements. While caff eine that is derived from leaves and beans contains over 1,000 anti-oxidant-type biological compounds, which positively aff ect health and appear to lower the risk of conditions such as Type 2 diabetes, caff eine supplements may have the opposite eff ect. Non-natural stimulants must be used sparingly and with caution. Lastly, while much research shows that the consumption of


caff eine from sources such as green tea can signifi cantly increase weight loss, this eff ect does not appear to exist in groups of women who consume caff eine regularly. Therefore, while scientists are still not sure how or why it works, the morality of its use is still debated and the eff ects vary from person to person, the benefi ts of caff eine to sporting performance are well documented. If you are going to ingest caff eine in an at empt to enhance your performance, it is crucial to test its eff ects in training beforehand and start with a low dose and then build up. Also, if no change in performance is seen, stop. Elite athletes who are concerned with drug testing can keep up to date with caff eine’s doping status by using the Global Drug Reference Online website (globaldro.com). For the rest of us, the question is not just how we take caff eine but if we should at all. ○


Caff eine Content 50-60mg


100-110mg 50-60mg 30-40mg 10mg 35mg 160mg 80mg 50mg 0, 25, or 50mg (dependent on fl avour)


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