Polyphenol-Rich Sorghum Bicolor Extract Enhances Strength Recovery After Eccentric Exercise

ABSTRACT: Mitchinson, CJ, Kwak, M, Succi, PJ, Benitez, B, and Bergstrom, HC. Polyphenol-rich sorghum bicolor extract enhances strength recovery after eccentric exercise. J Strength Cond Res 39(8): e951-e959, 2025-This randomized, double-blind, placebo (PL) controlled trial examined the effects of a polyphenol-rich supplement on muscular strength recovery after eccentric exercise. Twenty-nine men (mean ± SD , age = 23.1 ± 3.8 years) were randomly assigned to a high- (500 mg·d -1 ; n = 9) or low- (250 mg·d -1 ; n = 10) dose polyphenol-rich sorghum bicolor extract, or PL ( n = 10) group and completed a 17- to 18-day supplementation period, with eccentric exercise on day 14 + 1. Unilateral forearm flexion strength, muscle thickness (MT), pain pressure threshold (PPT), perceived recovery, and pain ratings were recorded before (baseline) and at 24, 48, and 72 hours after maximal eccentric exercise. Analyses included mixed-model ANCOVAs, ANOVAs, and post hoc Bonferroni corrected pairwise comparisons ( p < 0.05). After 18-25% strength losses from baseline to 24 hours, strength increased significantly from 24 to 48 hours for the high-dose group (mean difference [CI 95% ] = 5.7 N·m [2.2-9.3]; p < 0.001; d = 0.568) and from 24 to 72 hours for the low-dose group (8.3 N·m [4.4-12.2]; p < 0.001; d = 0.848), while strength remained unchanged from 24 to 72 hours for the PL group ( p = 0.101-1.000). There were no changes in MT or PPT from 24 to 72 hours. Pain ratings significantly decreased, and perceived recovery increased at 72 hours relative to 24 and 48 hours for all groups across time ( p = 0.001-0.012). Supplementation with a high- and low-dose polyphenol-rich sorghum bicolor extract increased recovery of muscular strength at faster rates than PL after eccentric exercise but had no meaningful effect on muscle swelling, perceived pain, or recovery. A polyphenol-rich supplement may enhance performance in subsequent exercise sessions and promote increased training volume.