Effect of <i>Lactiplantibacillus plantarum</i> GKK1 Supplementation on Exercise-Induced Fatigue, Muscle Damage, and Recovery in Healthy Men: A Randomized, Double-Blind, Placebo-Controlled Trial.

Background: Exercise-induced fatigue (EIF) and exercise-induced muscle damage (EIMD) impair neuromuscular performance and delay post-exercise recovery. However, human evidence regarding the structural and functional recovery kinetics following Lactiplantibacillus plantarum GKK1 supplementation remains limited.

Objective: This randomized, double-blind, placebo-controlled trial investigated whether 4 weeks of L. plantarum GKK1 supplementation improves functional recovery and modulates biochemical responses after an EIMD protocol in healthy men.

Methods: Forty-eight healthy men with no regular exercise habits were randomly assigned to receive either placebo ( n = 24) or L. plantarum GKK1 (two capsules daily, totaling 1.0 × 10 11 CFU; n = 24) for 28 consecutive days. The trial was registered at ClinicalTrials.gov (NCT06893549). After supplementation, participants completed 100 maximal plyometric jumps. Countermovement jump (CMJ), isometric mid-thigh pull (IMTP), and Wingate anaerobic performance were assessed before EIMD and at 3, 24, and 48 h post-EIMD. Blood biomarkers of muscle damage, inflammation, oxidative stress, endocrine response, and sympathoadrenal activity were analyzed, and urinary 3-methylhistidine and creatinine were measured.

Results: Compared with placebo, GKK1 supplementation was associated with smaller post-exercise decrements in the CMJ rate of force development, relative peak force, jump height, IMTP relative peak force and peak RFD, and Wingate anaerobic performance ( p

Conclusion: These

Findings: suggest that GKK1 may be a safe nutritional strategy to facilitate functional recovery, attenuate secondary inflammatory responses and modulate urinary markers associated with muscle breakdown following muscle-damaging exercise in healthy young men.