Abstract

Athletes are always searching for nutritional supplements that will give them an advantage over their competitors. Within the last few years a new ergogenic aid has been used by many succesful athletes: Creatine. In humans, over 95% of the total creatine content (TCr) is located in skeletal muscle of which approximately a third as free creatine (Crf). The remainder is present as phosphocreatine (PCr). Daily turnover of creatine to creatinine for a 70 kg male has been estimated to be around 2 g. On average, about 1 g of this amount will be replaced by exogenous sources, the remainder has to be derived from endogenous synthesis. Though its discovery dates back to 1832, the effect of creatine on performance has only recently been studied. Present studies have shown that both Crf and PCr content of muscle can be increased by creatine supplementation. An effective way to obtain immediate and sustained performance benefits from creatine ingestion is to use a loading dose of 0.3 gram per kilogram body mass per day (g/kgBM/day) for 5-6 days followed by a maintenance dose of 0.03 g/kgBM/day. This is accompanied by an increase in total body mass of +/-0.5-1.6 kg. The beneficial effects of creatine loading appear to be limited to high intensity intermittent exercise. The metabolic background for this increase in performance is not entirely clear. Hypotheses an this topic include a higher preexercise PCr content, a higher PCr resynthesis rate or a reduction in loss of ATP. A combination of this hypotheses as well as the possibility of morphological changes can not be ruled out. Still, not everybody will respond to creatine supplementation. Verf.-Referat