Can caffeine enhance endurance performance?
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Caffeine has been considered a stimulant and is used by many individuals in normal daily life as well as by athletes. Caffeine and related substances are found naturally in foods and beverages, such as coffee, teas, and chocolate; and as part of recipes, such as in various soft drinks. Coffee contains caffeine whereas tea contains theophylline and chocolate contains theobromine. These factors are considered stimulants as they impact the CNS and increase alertness which alone can improve the enjoyment of exercise and help people perform at a higher level. |
Caffeine and related substances also enhance and prolong the effects of certain hormones such as glucagon and epinephrine in fat tissue. If fat release is increased and made more available to muscle then more fat might be used during aerobic exercise and improve performance and help lean the body.
Several studies have reported that the beneficial effects of caffeine on performance are negated in people who use caffeine daily (coffee, soft drinks, etc). However, by going caffeine free for several days prior to an event, caffeine may enhance performance. Recent studies have shown that caffeine ingestion can indeed enhance endurance performance. Based on the current research 3 to 6 milligrams of caffeine per kilogram body weight prior to training or competition might enhance endurance performance. Meanwhile levels exceeding 9 milligrams per kilogram body weight might decrease performance.
Caffeine seems to enhance mental alertness in smaller doses (200 milligrams), although many individuals complain of nervousness and anxiety when larger doses are used (> 400 milligram). A cup of coffee contains 100 to 150 milligrams of caffeine while a cup of tea and cola contain 25 to 60 milligrams. The over-the-counter stimulant Vivarin contains 200 milligrams of caffeine per tablet. Caffeine is metabolized and removed from the body fairly slowly. It may take several hours for the caffeine in one cup of coffee to be completely removed in the urine.
Can glycerol support better hydration for athletes?
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Glycerol has also been considered a candidate for supplementation during endurance events. This notion is based upon glycerol’s potential to be converted to glucose in the liver. The glucose could then circulate to muscle and support muscle operations during exercise. Theoretically, this could decrease the rate of breakdown of glycogen stores. However, it seems that the torpid rate of converting glycerol to glucose seriously decreases its candidacy. Alternatively, glycerol supplementation in conjunction with water consumption may be of benefit to endurance athletes preparing to perform in warmer environments. |
It may be that glycerol can enhance water retention prior to an event and thus may allow more sweat to be lost prior to any reductions in performance due to dehydration. Scientists have also reported that glycerol supplementation prior to an event increases heat tolerance during competition in warmer environments-perhaps another potential aid for athletes competing in warmer environments without ample opportunity to drink fluids during training and competition. One example of this type of competition might be soccer. However, glycerol may lead to digestive tract discomfort so athletes will have to experiment here as well.
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