Low Dose of β-Hydroxy-β-Methylbutyrate (HMB) Alleviates Muscle Strength Loss and Limited Joint Flexibility following Eccentric Contractions

Objective:The optimal dose of beta-hydroxy-beta-methylbutyrate (HMB) required for decreasing muscle damage remains unknown. Therefore, this study investigated the supplemental effect of low-dose HMB on muscle damage following eccentric contractions (ECCs) of human elbow flexors. Methods:Twenty untrained men (aged 20-26; height, 169.4 +/- 5.7 cm; weight, 68.2 +/- 11.3 kg; body mass index, 23.7 +/- 3.3) completed the double-blind, placebo-controlled, parallel design study. The subjects were randomly assigned to the ingestion of HMB supplement (HMB, n = 10) or placebo group (PL, n = 10). After the subjects of 1.5 g HMB or placebo pills per day for 2 weeks, they performed six sets of 10 ECCs at 100% maximal voluntary contraction (MVC) using dumbbell. Changes in MVC torque, range of motion (ROM), upper arm circumference, muscle soreness, and muscle stiffness were assessed before, immediately after, 1, 2, 3, 5 days after exercise. Results:MVC torque was significantly higher in the HMB group than in the PL group immediately after (HMB, -56.8%; PL, -67.1%) as well as 3 (HMB: -25.5%, PL: -48.7%) and 5 (HMB: -22.5%, PL: -44.0%) days after performing ECCs (p < 0.05). Additionally, ROM was significantly higher in the HMB group than in the PL group immediately after (HMB, -29.8%; PL, -50.5%) and 5 (HMB: -26.1%, PL: -43.3%) days after performing ECCs (p < 0.05). No between-group differences were observed in other muscle damage markers. Conclusion:The low-dose HMB supplementation demonstrated a moderate overall impact and played a beneficial role in muscle dysfunction and joint flexibility following ECCs.

Automated summary

The study found that low-dose HMB supplementation significantly improved maximal voluntary contraction torque and range of motion in muscles, and helped reduce muscle damage. The results of this study provide new insights into the application of HMB in reducing muscle damage.