Time for an energy boost?

WENDY SWEET

Time for an energy boost?

Caffeine might not be the answer.

For a substance that is naturally produced by plants as a pesticide toward insects, caffeine has certainly found its place in society. Consumption of coffee and energy drinks is on the rise. With the interest in caffeine as an energy booster, there is also an interest in caffeine as an ergogenic potential in sports performance. It’s an accepted ergogenic aid by the International Olympic Committee and athletes have used it for years to enhance performance. So with winter sports already in full flight, it seems timely to remind PE teachers and coaches of not only its mechanisms in exercise performance but also its risks.

Caffeine as a performance aid

Caffeine enhances endurance performance. It very simply stimulates the central nervous system (CNS) and in technical terms acts as an adenosine-receptor antagonist throughout the body. Although studies are not entirely clear on the exact mechanism of caffeine as an ergogenic aid, the general consensus is that caffeine stimulates a number of different actions and re-actions at the cellular level. The intake of caffeine triggers an increase in blood circulation, heart rate, urine output, gastric secretions and causes a decrease in glucose metabolism. How does all this happen? Well, as caffeine is metabolised in the liver, it stimulates the release of the adrenal hormone, adrenaline, into the blood-stream. Adrenaline (or epinephrine), helps to “un-lock” fat stored in adipose tissue and/or skeletal muscle, releasing these stored triglycerides out to the general circulation. This process is known as “lipolysis.” Subsequent break-down of these triglycerides means that Free Fatty Acid (FFA) levels are increased in the circulation. These circulating FFA’s become available as a source for energy production in the early phase of exercise, thus “sparing” the use of glycogen stored in muscles. This “glycogen-sparing” effect of caffeine is critical in sports performance as it helps delay the early onset of fatigue. In endurance-related cardiovascular activities of 30 to 60 minutes, caffeine intake may well reduce the need to use muscle carbohydrate (glycogen). Its effects haven’t been replicated in short-term, high-intensity exercise or in recreational athletes, especially females. On a further note, taking caffeine pills to support weight loss has not been confirmed in any research studies.

Most interestingly for athletes, though, is the research identifying caffeine as having analgesic properties. In the context of sports and exercise, it may help to ameliorate pain. Although this isn’t a good thing to

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encourage in young athletes, the secondary effects of caffeine consumption may well be related to increasing their pain tolerance during sporting activities.

Caffeine and hydration

Coffee, tea and caffeine are regularly described as diuretics. It was therefore always thought that despite the known ergogenic properties of caffeine, this could well be negated by the effect caffeine has on hydration before, during and after exercise. More recent studies, though, don’t support this acute diuretic effect. In fact some studies show quite the opposite. During exercise of 70 to 80 minutes or more, intake of caffeinated beverages (including those containing carbohydrate and electrolytes), have re-hydrating effects almost identical to non-caffeinated beverages.

How much caffeine and when?

Caffeine is rapidly absorbed and most studies show that plasma concentrations reach maximal level in about one hour. After that, it takes around three to four to catabolise (break-down) caffeine so the exact timing of caffeine ingestion before sports performance has not really been clarified. Although the performance-enhancing benefits of caffeine depend on people’s tolerance and habitual intake of the substance as well as the size of the individual, some studies indicate that 3mg/kg was effective for increasing endurance in prolonged exercise.

For some athletes, though, the risks of caffeine consumption outweigh the benefits. High consumption of caffeine must not be endorsed. In some individuals it has been linked to cardiac arrhythmias and high blood pressure (hypertension), so caution must be taken in any athletes, no matter the age, who are on clinical medication and/ or have a known cardiac history. Intake of high amounts of caffeinated drinks for these athletes prior to sports or exercise could literally be deadly.

Ethical issues

Despite the number of teens drinking caffeine-containing energy drinks and coffee and tea, the ingestion of caffeine as a sports enhancement strategy is a difficult one to resolve. In competition, caffeine isn’t illegal. It is also, for some athletes, a powerful tool to increase exercise capacity in both training and competition. In this regard, it must also be stated that unlike sports drinks or vitamin/ mineral supplementation, an athlete knowingly taking high doses of caffeine for the express purpose of gaining a competitive advantage pushes them into the “unethical” category. It may well lead them to make similar decisions around trying other stimulants, so teachers and coaches are advised to monitor the intake of caffeine beverages in their young athletes and instead steer them toward a nutritious, energy-rich diet with adequate intake of water to replace fluid lost in training and competition. “For some athletes, though, the risks of caffeine consumption outweigh the benefits. High consumption of caffeine must not be endorsed. In some individuals it has been linked to cardiac arrhythmias and high blood pressure.”