Oligonol<sup>Ⓡ</sup> Increases the Distance Covered in the 12-Minute Run Test in Long-Distance Runners: A Randomized, Double-Blind, Placebo-Controlled, Parallel Trial

Introduction: Oligonol® which is a standardized oligomerized-polyphenol from Litchi chinensis fruit extract (OPLFE), has been reported to have multiple beneficial effects on exercise performance. This study evaluated the effects of OPLFE on endurance performance in long-distance runners. Methods: A randomized, double-blind, placebo-controlled, parallel trial was conducted in which 34 long-distance runners (male and female adults aged 45–64) were assigned to receive 200 mg/day of OPLFE or placebo as the intervention for 60 days. The 12-minute run tests were conducted at the initial and final visits to evaluate the primary outcome (running distance), and secondary outcomes included heart rate, rating of perceived exertion (RPE) score, and body composition. Statistical significance was set at *P < 0.05. Results: The primary outcome of running distance in the 12-minute run test was significantly increased in the OPLFE group compared to the placebo group (OPLFE: 2.97 ± 0.36 km vs. placebo: 2.95 ± 0.36 km, P = 0.038), based on an analysis of covariance with baseline value as the covariate and group as the factor. The secondary outcome of RPE score also showed a significant decrease in the OPLFE group compared to the placebo group (OPLFE: 14.5 ± 2.0 vs. placebo: 16.4 ± 2.0, P = 0.003). No differences were observed in the other secondary outcomes. Conclusions: OPLFE intake increased the distance covered in the 12‑minute run test and reduced RPE. These findings suggest that OPLFE may improve endurance performance in middle‑aged male and female adults.