Effects of ribose supplementation on adenine nucleotide metabolism in human skeletal muscle during high-intensity exercise

During periods of intense exercise the adenine nucleotide pool in skeletal muscle becomes partially depleted. Ribose has been shown to increase rates of both purine salvage and adenine nucleotide de novo synthesis in rat skeletal muscle. However, to date no research has been conducted on the effects of ribose on adenine nucleotide levels in human skeletal muscle. Therefore, the purpose of this investigation was to determine the effects of ribose supplementation on adenine nucleotide levels in human skeletal muscle during high-intensity exercise. To do this, an 11-day supplementation of either ribose (20 g.d-1) or placebo (glucose 20 g•d-1) was given to 16 healthy male subjects. After 72 hours of supplementation, the subjects performed five-days of high-intensity exercise designed to elicit significant reductions in adenine nucleotides. A 65 hour recovery period was completed following the exercise protocol. Muscle biopsies were performed at four different time points during the supplementation/exercise period.The exercise protocol elicited significant decreases in skeletal muscle adenine nucleotide levels of both the ribose and placebo groups (p<0.05). However, ribose supplementation was shown to partially attenuated the adenine nucleotide decrease. The placebo group demonstrated a 39% decrease, while the ribose group dropped 23% in TAN levels (p<0.05). The largest decreases were observed in ATP for both groups; however, the decreases were significantly greater in the placebo group (p<0.05). Both groups displayed a similar amount of replenishment in adenine nucleotides 65 hours following the 5-day exercise period. No differences were demonstrated in ADP or AMP for either the ribose and placebo groups throughout the investigation. Both groups displayed an increase in E MP post-exercise, but the increase was only significant in the ribose group (p