| Sumario: | Many athletes make extensive use of ergogenic aids in the hope that they can favourably affect athletic performance and increase lean body mass. Supplementation with creatine, glutamine, carnitine, leucine and its metabolite hydroxymethylbutyrate (HMB), and branched chain amino acids (BCAA) has been hypothesised to assist in the achievement of optimal sports performance. Despite an increasing amount of scientific evidence and popularity, uncertainty about the effectiveness and safety of these supplements still exists. A survey was undertaken of the supplements being promoted in the most popular sports magazines in Australia. Approximately one quarter of the advertisements for supplements in the magazines surveyed were for creatine (54%), glutamine (24%), HMB (20%), and BCAA (2%). A critical literature review of trials of the effect of these ergogenic aids on exercise performance trials was conducted. Creatine supplementation appears to have substantial scientific support as a safe and effective nutritional strategy to enhance exercise performance and improve training adaptations in high-intensity, short-term (? 30 seconds) exercise tasks, with limited recovery time between repetitions. Carnitine supplementation has been reported to increase exercise capacity in disease states. However, in healthy athletes carnitine was not shown to have an ergogenic effect. There was limited evidence that the use of HMB supplementation resulted in gains in strength and body mass. There was an abundance of clinical evidence supporting the requirement for exogenous glutamine in critically ill patients and in the over-training syndrome. However, for healthy subjects, the few scientific studies available suggested that glutamine is only of benefit for athletes with true deficiency. Research findings regarding the effects of BCAA supplementation are somewhat equivocal. Most reviews evaluating the central fatigue hypothesis suggest that BCAA is not an effective ergogenic supplement, nor is it ergolytic. Further research is needed for better evaluation of the safety and efficacy of many of these supplements, especially focussing on their use in specific sporting situations.
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