Effect of inosine supplementation on aerobic and anaerobic cycling performance

Ten competitive male cyclists completed a Wingate Bike Test (WIN), a 30- min self-paced cycling performance bout (END), and a constant load, supramaximal cycling sprint (SPN) to fatigue following 5 d of oral supplementation (5,000 mg · day^-1) with inosine and placebo. Blood samples were obtained prior to and following both supplementation periods, and following each cycling test. Uric acid concentration was higher (P < 0.05) following supplementation with inosine versus placebo, but 2,3-DPG concentration was not changed. The data from WIN demonstrate that there were no significant differences in peak power (8.5 ± 0.3 vs 8.4 ± 0.3 W · kg body mass^-1), end power (7.0 ± 0.3 vs 6.9 ± 0.2 W · kg body mass^-1), fatigue index (18 ± 2 vs 18 ± 2%), total work completed (0.45 ± 0.02 vs 0.45 ± 0.02 kJ · kg body mass^-1 · 30-s^-1), and post-test lactate (12.2 ± 0.5 vs 12.9 ± 0.6 mmo1 · l^-1) between the inosine and placebo trials, respectively. No difference was present in the total amount of work completed (6.1 ± 0.3 vs 6.0 ± 0.3 kJ · kg body mass^-1) or post-test lactate (8.4 ± 1.0 vs 9.9 ± 1.3 mmol · l^-1) during END between the inosine and placebo trials, respectively. Time to fatigue was longer (P < 0.05) during SPN for the placebo (109.7 ± 5.6 s) versus the inosine (99.7 ± 6.9 s) trial, but post-test lactate (14.8 ± 0.7 vs 14.6 ± 0.8 mmol · l^-1) was not different between the treatments, respectively. These findings demonstrate that prolonged inosine supplementation does not appear to improve aerobic performance and short term power production during cycling and may actually have an ergolytic effect trader some test conditions.