However, they measured creatine kinase and myoglobin 24 h and 48 h after exercise, which might explain the disparate findings. In marathon runners, post-race
creatine kinase was significantly elevated among faster compared to slower runners and the elevations of creatine kinase drawn 24 hours after a marathon were inversely related to the finishing times . Skenderi et al. described 39 runners in the Spartathlon, a 246 km ultra-marathon, which the athletes completed within 33.3 (±0.5) h . The finishing time was not correlated to the post race creatine kinase concentration, as has been found in the present study. Duration of amino acid supplementation Our athletes ingested the amino acids as a pre-race load of 12 g and then 4 g at each aid station during the 100 km ultra-marathon. The total amount was 52.5 g amino acids and Fulvestrant in vitro the time of supplementation was between 12 and 13 hours. This time period might be too short to show an effect of the amino acid supplementation on performance. An amino acid supplementation period of two weeks , four weeks  or even eight weeks  showed beneficial effects on performance. The supplementation of amino acids for a shorter period may nonetheless have positive effects on serum variables or muscle soreness. Shimomura et al. demonstrated that the
ingestion of 5 g of branched-chain amino acids 15 minutes prior to seven sets of 20 squats per set reduced the delayed onset of muscle soreness and muscle Selleckchem Compound Library fatigue for several days after exercise . The duration of supplementation might also have been too short to show an effect on creatine kinase. Consuming 12 g of branched-chain amino acids during seven days reduced the increase of creatine kinase and lactate dehydrogenase after performance . Ohtani et al. showed a decrease in post exercise creatine kinase serum concentrations compared
to pre-exercise when athletes ingested, three times per day, 2.2 g of a mixture of amino acids during one month . However, there is data that shows that the ingestion of amino acids during performance has an effect on variables of skeletal muscle damage. In a recent study in untrained through male cyclist, the ingestion of branched-chain amino acids reduced the increase in creatine kinase serum concentration after performance . The disparate findings might be explained by the fact that those researchers investigated untrained subjects during cycling where as we investigated well-trained and experienced ultra-runners. Two recent studies showed an enhanced performance when both protein and carbohydrates were ingested during endurance performances. In two studies of cyclists, the combined intake of carbohydrate and protein during exercise enhanced performance [16, 17]. In the first study of Saunders et al., the subjects were given a carbohydrate and protein beverage with 7.3% carbohydrate and protein plus 1.