Short-Term Effects of Broccoli-Derived Glucoraphanin on Recovery from Eccentric Muscle Damage: A Double-Blind Randomized Crossover Study

Background/Objectives: Broccoli-derived glucoraphanin (a sulforaphane precursor that activates Nrf2 defenses) may aid repair; however, its short-term effects in humans remain unknown. This study aimed to evaluate whether short-term supplementation with broccoli-derived glucoraphanin improves recovery from exercise-induced muscle damage. We hypothesized that short-term supplementation with broccoli-derived glucoraphanin would attenuate exercise-induced muscle damage and accelerate recovery. Methods: In a randomized, double-blind, placebo-controlled crossover design, fifteen participants consumed either high-glucoraphanin broccoli powder (320 μg) or placebo for two weeks, followed by elbow flexor eccentric exercise. Strength, soreness, creatine kinase (CK), range of motion (ROM), arm girths, and ultrasound-assessed muscle and tendon morphology were measured at baseline, immediately post-exercise, and at 48 and 96 h post-exercise. Results: Significant main effects of time were observed for isometric and isokinetic torque (p < 0.05), CK (p < 0.05), soreness (p < 0.05), and structural swelling markers (p < 0.05), confirming exercise-induced muscle damage. However, there were no significant Time × Supplement interactions for any variable (p > 0.05), indicating that glucoraphanin did not influence recovery dynamics. Conclusions: These findings suggest that short-term high-dose broccoli supplementation reconstituted with hot water does not modulate recovery following eccentric muscle damage under the conditions tested, including the chosen preparation method and experimental context.