Effect of daily intake of a rice fermented beverage on endurance exercise performance in male college student athletes

Abstract

We recently developed a rice fermented beverage (RFB) that contains a wide variety of ergogenic nutrients (e.g. carbohydrates [CHOs], amino acids, and rice-derived phytochemicals). Although we showed a potential for prototype-RFB to promote post-exercise muscle glycogen restoration in rats, it is unclear whether RFB has ergogenic effects on human performance. Therefore, this study aimed to investigate the effect of daily supplementation of RFB on endurance exercise performance in male college student athletes. In this randomized double-blind crossover placebo-controlled study, 14 male college athletes (mean age, 20.2 ± 1.0 year) consumed either RFB or placebo for 3 weeks (100 mL/day) and performed ramp and constant workload cycle exercise tests before and after the supplementation period. The constant exercise test consisted of 40 min of cycling at 90% anaerobic threshold (AT) followed by increasing workload (30% AT every 10 min) until exhaustion. The amount of change in maximum workload and oxygen uptake/workload in the ramp-cycling test after supplementation tended to be higher and lower, respectively, in the RFB than in the placebo group. In the constant exercise test, blood lactate level was significantly lower in the RFB than in the placebo group during the 90% AT exercise period (p < 0.05). Moreover, a moderate positive linear correlation was found between the amount of change in time to exhaustion and Δ_{Exhaustion−90%ATfinal} CHO oxidation when RFB was consumed (r = 0.661, p < 0.05). These results suggest that daily RFB intake may be beneficial for improving endurance exercise performance in trained humans.