β-alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters
β-alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters
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DOI：
10.1152/japplphysiol.00397.2007
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发表时间：
2007-11-01
影响因子：
3.3
通讯作者：
Achten, Eric
中科院分区：
文献类型：
--
作者：
Derave, Wim;Oezdemir, Mahir S.;Achten, Eric
肌肽（β -丙氨酰- l-组氨酸）在人体骨骼肌中存在高浓度。摄入-丙氨酸，肌肽的限速前体，已被证明可以提高肌肉肌肽的含量。我们的目的是通过质子磁共振波谱（proton magnetic resonance spectroscopy，简称proton MRS）来研究在400米短跑训练的竞技运动员中，在4周内口服β -丙氨酸是否会提高小腿肌肌肽含量并影响运动表现。15名男性运动员参加了一项安慰剂对照的双盲研究，他们在4周内口服4.8克/天的β -丙氨酸或安慰剂。用质子mrs测定比目鱼肌和腓肠肌肌肽浓度，通过5次30次最大自主膝关节伸展时的等速运动测试、45%最大自主收缩时等距收缩时的耐力测试和室内400米跑步时间来评估运动表现。补充β -丙氨酸显著提高了比目鱼肌（+ 47%）和腓肠肌（+ 37%）的肌肽含量。在安慰剂组中，肌肽在比目鱼肌中保持稳定，而腓肠肌中肌肽增加了16%。-丙氨酸组在第4次和第5次的动态膝关节伸展扭矩显著改善，而安慰剂组则没有。等长耐力和400米比赛时间不受治疗的影响。综上所述，1)质子磁共振可用于无创定量人体肌肉肌肽含量；2)短跑训练运动员口服β -丙氨酸补充剂可增加肌肉肌肽；3)肌肽负荷轻微但显著地减轻了反复力竭动态收缩时的疲劳；4)肌肉肌肽的增加并没有提高等长耐力和400米比赛时间。
Carnosine ( beta- alanyl- L-histidine) is present in high concentrations in human skeletal muscle. The ingestion of beta- alanine, the rate- limiting precursor of carnosine, has been shown to elevate the muscle carnosine content. We aimed to investigate, using proton magnetic resonance spectroscopy ( proton MRS), whether oral supplementation with beta- alanine during 4 wk would elevate the calf muscle carnosine content and affect exercise performance in 400- m sprint- trained competitive athletes. Fifteen male athletes participated in a placebo- controlled, double- blind study and were supplemented orally for 4 wk with either 4.8 g/ day beta- alanine or placebo. Muscle carnosine concentration was quantified in soleus and gastrocnemius by proton MRS. Performance was evaluated by isokinetic testing during five bouts of 30 maximal voluntary knee extensions, by endurance during isometric contraction at 45% maximal voluntary contraction, and by the indoor 400- m running time. beta- Alanine supplementation significantly increased the carnosine content in both the soleus ( + 47%) and gastrocnemius ( + 37%). In placebo, carnosine remained stable in soleus, while a small and significant increase of + 16% occurred in gastrocnemius. Dynamic knee extension torque during the fourth and fifth bout was significantly improved with beta- alanine but not with placebo. Isometric endurance and 400- m race time were not affected by treatment. In conclusion, 1) proton MRS can be used to noninvasively quantify human muscle carnosine content; 2) muscle carnosine is increased by oral beta- alanine supplementation in sprint- trained athletes; 3) carnosine loading slightly but significantly attenuated fatigue in repeated bouts of exhaustive dynamic contractions; and 4) the increase in muscle carnosine did not improve isometric endurance or 400-m race time.