Thomson Jasmine S, Watson Patricia E, Rowlands David S
The Institute of Food, Nutrition & Human Health, Massey University, Albany, New Zealand.
J Strength Cond Res. 2009 May;23(3):827-35. doi: 10.1519/JSC.0b013e3181a00d47.
The dietary supplement beta-hydroxy-beta-methylbutyrate (HMB) is claimed to increase strength, lean body mass, and decrease fat mass when used in conjunction with resistance training. Although there is some support for these claims, the evidence is not conclusive, and it is even less so for resistance trained individuals. Therefore, we aimed to further elucidate the effects of HMB supplementation in trained men. A randomized, double-blind, controlled study design was used to investigate the effects of supplementing 22 resistance trained men with 3 g.d of HMB or corn starch placebo for 9 weeks with resistance training. The effect of HMB on strength was determined using the 1-repetition maximum (1RM) method for the lower body (leg extension) and upper body (bench press, bicep preacher curl) at baseline and after the supplementation period. Body composition was assessed by skinfolds and bioelectrical impedance analysis (BIA). Overall, 9 weeks' HMB supplementation resulted in a clear-cut, trivial increase in combined averaged strength measures of 1.6% (90% confidence limits: +/-4.3%). When considered in isolation, however, leg extension 1RM increased by a substantial 9.1% (90% confidence limits: +/-7.5%), but the effect on upper-body strength was inconclusive (bench press: -1.9 +/- 9.3%; bicep curl: -1.7 +/- 4.7%). Based on BIA estimates, HMB had a decreasing (although inconclusive) influence on fat mass of -9 +/- 14%, but it had a clear, trivial effect on fat-free mass of 0.2 +/- 2.2%. The magnitude of change in body mass was trivial, but the probability of substantial reductions in skinfold thicknesses ranged from negligible to likely. In previously trained men, supplementation of HMB in conjunction with resistance training provides a substantial benefit to lower-body strength, but it has negligible effects on body composition.
膳食补充剂β-羟基-β-甲基丁酸酯（HMB）据称在与抗阻训练同时使用时，可增强力量、增加瘦体重并减少脂肪量。尽管这些说法有一定支持证据，但证据并不确凿，对于经过抗阻训练的个体更是如此。因此，我们旨在进一步阐明补充HMB对训练有素的男性的影响。采用随机、双盲、对照研究设计，调查22名经过抗阻训练的男性，在进行抗阻训练的同时，每天补充3克HMB或玉米淀粉安慰剂，为期9周的效果。使用1次重复最大值（1RM）方法，在基线期和补充期后，测定HMB对下半身（腿伸展）和上半身（卧推、牧师椅弯举）力量的影响。通过皮褶厚度测量和生物电阻抗分析（BIA）评估身体成分。总体而言，补充HMB 9周后，综合平均力量指标明显但轻微增加了1.6%（90%置信区间：±4.3%）。然而，单独来看，腿伸展1RM显著增加了9.1%（90%置信区间：±7.5%），但对上半身力量的影响不明确（卧推：-1.9±9.3%；二头肌弯举：-1.7±4.7%）。根据BIA估计，HMB对脂肪量有减少作用（尽管不明确），为-9±14%，但对去脂体重有明显但轻微的影响，为0.2±2.2%。体重变化幅度微不足道，但皮褶厚度大幅减少的可能性从可忽略不计到有可能。在之前经过训练的男性中，补充HMB并结合抗阻训练对下半身力量有显著益处，但对身体成分的影响可忽略不计。
