Department of Physiology and Biophysics, room 105, Institute of Biomedical Science, University of São Paulo, Av. Prof. Lineu Prestes, 1524, Prédio Biomédicas I, Cidade Universitária, Butantã, São Paulo, SP, CEP:05508-900, Brazil.
Eur J Appl Physiol. 2012 Jul;112(7):2531-7. doi: 10.1007/s00421-011-2224-5. Epub 2011 Nov 11.
Beta-hydroxy-beta-methylbutyrate (HMB) is a metabolite derived from leucine. The anti-catabolic effect of HMB is well documented but its effect upon skeletal muscle strength and fatigue is still uncertain. In the present study, male Wistar rats were supplemented with HMB (320 mg/kg per day) for 4 weeks. Placebo group received saline solution only. Muscle strength (twitch and tetanic force) and resistance to acute muscle fatigue of the gastrocnemius muscle were evaluated by direct electrical stimulation of the sciatic nerve. The content of ATP and glycogen in red and white portions of gastrocnemius muscle were also evaluated. The effect of HMB on citrate synthase (CS) activity was also investigated. Muscle tetanic force was increased by HMB supplementation. No change was observed in time to peak of contraction and relaxation time. Resistance to acute muscle fatigue during intense contractile activity was also improved after HMB supplementation. Glycogen content was increased in both white (by fivefold) and red (by fourfold) portions of gastrocnemius muscle. HMB supplementation also increased the ATP content in red (by twofold) and white (1.2-fold) portions of gastrocnemius muscle. CS activity was increased by twofold in red portion of gastrocnemius muscle. These results support the proposition that HMB supplementation have marked change in oxidative metabolism improving muscle strength generation and performance during intense contractions.
β-羟基-β-甲基丁酸（HMB）是亮氨酸的代谢产物。HMB 的抗分解代谢作用已有充分的文献记载，但它对骨骼肌力量和疲劳的影响仍不确定。在本研究中，雄性 Wistar 大鼠补充 HMB（每天 320mg/kg）4 周。安慰剂组仅接受生理盐水。通过坐骨神经直接电刺激评估比目鱼肌的肌肉力量（抽搐和强直力）和抗急性肌肉疲劳能力。还评估了比目鱼肌红白部的 ATP 和糖原含量。还研究了 HMB 对柠檬酸合酶（CS）活性的影响。HMB 补充可增加肌肉强直力。收缩和弛豫时间的峰值无变化。HMB 补充后，在剧烈收缩活动期间抗急性肌肉疲劳的能力也得到改善。比目鱼肌红白部的糖原含量均增加（白肌增加五倍，红肌增加四倍）。HMB 补充还增加了比目鱼肌红白部的 ATP 含量（红肌增加两倍，白肌增加 1.2 倍）。比目鱼肌红肌的 CS 活性增加了两倍。这些结果支持以下观点，即 HMB 补充可显著改变氧化代谢，改善剧烈收缩期间的肌肉力量产生和性能。
