Abstract
Introduction Studies utilizing beta-hydroxy-beta-methylbutyrate (HMB) supplementation in trained populations are limited. No long-term studies utilizing HMB free acid (HMB-FA) have been conducted. Therefore, we investigated the effects of 12 weeks of HMB-FA supplementation on skeletal muscle hypertrophy, body composition, strength, and power in trained individuals. We also determined the effects of HMB-FA on muscle damage and performance during an overreaching cycle.MethodsA three-phase double-blind, placebo- and diet-controlled randomized intervention study was conducted. Phase 1 was an 8-week-periodized resistance-training program; Phase 2 was a 2-week overreaching cycle; and Phase 3 was a 2-week taper. Muscle mass, strength, and power were examined at weeks 0, 4, 8, and 12 to assess the chronic effects of HMB-FA; and assessment of these, as well as cortisol, testosterone, and creatine kinase (CK) was performed at weeks 9 and 10 of the overreaching cycle.ResultsHMB-FA resulted in increased total strength (bench press, squat, and deadlift combined) over the 12-week training (77.1 ± 18.4 vs. 25.3 ± 22.0 kg, p < 0.001); a greater increase in vertical jump power (991 ± 168 vs. 630 ± 167 W, p < 0.001); and increased lean body mass gain (7.4 ± 4.2 vs. 2.1 ± 6.1 kg, p < 0.001) in HMB-FA- and placebo-supplemented groups, respectively. During the overreaching cycle, HMB-FA attenuated increases in CK (−6 ± 91 vs. 277 ± 229 IU/l, p < 0.001) and cortisol (−0.2 ± 2.9 vs. 4.5 ± 1.7 μg/dl, p < 0.003) in the HMB-FA- and placebo-supplemented groups, respectively.ConclusionsThese results suggest that HMB-FA enhances hypertrophy, strength, and power following chronic resistance training, and prevents decrements in performance following the overreaching.Electronic supplementary materialThe online version of this article (doi:10.1007/s00421-014-2854-5) contains supplementary material, which is available to authorized users.
Highlights
Studies utilizing beta-hydroxy-beta-methylbutyrate (HMB) supplementation in trained populations are limited
HMB free acid (HMB-FA) attenuated increases in creatine kinase (CK) (−6 ± 91 vs. 277 ± 229 IU/l, p < 0.001) and cortisol (−0.2 ± 2.9 vs. 4.5 ± 1.7 μg/dl, p < 0.003) in the HMB-FA- and placebo-supplemented groups, respectively. These results suggest that HMB-FA enhances hypertrophy, strength, and power following chronic resistance training, and prevents decrements in performance following the overreaching
Nissen et al (1996) became the first to demonstrate that supplementation of the leucine metabolite, beta-hydroxy-beta-methylbutyrate (HMB), combined with resistance training improved protein balance and augmented gains in lean body mass (LBM) and strength
Summary
Studies utilizing beta-hydroxy-beta-methylbutyrate (HMB) supplementation in trained populations are limited. We investigated the effects of 12 weeks of HMB-FA supplementation on skeletal muscle hypertrophy, body composition, strength, and power in trained individuals. HMB is thought to operate via enhanced recovery of damaged skeletal muscle tissue (Wilson et al 2008). These findings are not surprising as research clearly indicates that the initial weeks of training result in the highest magnitude of damage in an untrained population (Clarkson and Hubal 2002; McHugh et al 1999). It is likely that the most important independent variables in any study examining HMB supplementation in athletes may be the intensity and variability of the training protocol
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