The effects of oral administration of salts of aspartic acid on the metabolic response to prolonged exhausting exercise in man.

The effects of the oral administration of salts of aspartic acid on endurance capacity and metabolic responses to prolonged bicycle exercise have been investigated. Previous reports in man and in animals have suggested that this treatment can increase the capacity to perform muscular work by virtue of its effect on circulating ammonia levels. Eight healthy young male subjects exercised to exhaustion on a bicycle ergometer at a work load requiring approximately 75% of maximum oxygen uptake. This work test was performed after placebo administration or after ingestion of 6 g of potassium-magnesium aspartate over a 24-h period, using a double-blind protocol. Exhaustion was reached after 82.7 +/- 23.5 min (mean +/- SD) following aspartate treatment and after 85.4 +/- 26.5 min following the placebo. No differences in the blood glucose, lactate, or ammonia concentrations or in the plasma free fatty acid concentration between the two treatments were observed. The respiratory exchange ratio was the same on both occasions. These results show no beneficial effect of oral aspartate administration on work capacity in man and also suggest that the metabolic processes that occur during exercise are not influenced by this treatment.