Johnston Adam P W, Burke Darren G, MacNeil Lauren G, Candow Darren G
Department of Human Kinetics, St Francis Xavier University, Antigonish, Canada.
J Strength Cond Res. 2009 Jan;23(1):116-20. doi: 10.1519/jsc.0b013e31818efbcc.
Muscle and strength loss will occur during periods of physical inactivity and immobilization. Creatine supplementation may have a favorable effect on muscle mass and strength independently of exercise. The purpose of this study was to determine the effects of creatine supplementation on upper limb muscle mass and muscle performance after immobilization. Before the study, creatine-naïve men (n = 7; 18-25 years) were assessed for lean tissue mass (dual-energy X-ray absorptiometry), strength (1-repetition maximum [1RM] isometric single arm elbow flexion/extension), and muscle endurance (maximum number of single-arm isokinetic elbow flexion/extension repetitions at 60% 1RM). After baseline measures, subjects had their dominant or nondominant (random assignment) upper limb immobilized (long arm plaster cast) at 90 degrees elbow flexion. Using a single-blind crossover design, subjects received placebo (maltodextrin; 4 x 5 gxd-1) during days 1-7 and creatine (4 x 5 gxd-1) during days 15-21. The cast was removed during days 8-14 and 22-29. The dependent measures of lean tissue mass, strength, and endurance were assessed at baseline, postcast, and after the study. During immobilization, compared with isocaloric placebo, creatine supplementation better maintained lean tissue mass (Cr +0.9% vs. PLA -3.7%, p < 0.05), elbow flexor strength (Cr -4.1% vs. PLA -21.5%, p < 0.05), and endurance (Cr -9.6% vs. PLA -43%, p < 0.05), and elbow extensor strength (Cr -3.8% vs. PLA -18%, p < 0.05) and endurance (Cr -6.5% vs. PLA -35%, p < 0.05). These results indicate that short-term creatine supplementation attenuates the loss in muscle mass and strength during upper-arm immobilization in young men.
在身体不活动和固定期间，肌肉和力量会流失。补充肌酸可能对肌肉质量和力量产生有益影响，且与运动无关。本研究的目的是确定补充肌酸对上肢固定后肌肉质量和肌肉性能的影响。在研究开始前，对未服用过肌酸的男性（n = 7；18 - 25岁）进行瘦组织质量（双能X线吸收法）、力量（1次重复最大负荷[1RM]等长单臂肘屈伸）和肌肉耐力（60% 1RM时单臂等速肘屈伸的最大重复次数）评估。在基线测量后，受试者将其优势或非优势（随机分配）上肢在肘屈曲90度时进行固定（长臂石膏固定）。采用单盲交叉设计，受试者在第1 - 7天接受安慰剂（麦芽糊精；4×5 g·d⁻¹），在第15 - 21天接受肌酸（4×5 g·d⁻¹）。石膏在第8 - 14天和第22 - 29天拆除。在基线、拆除石膏后和研究结束后评估瘦组织质量、力量和耐力等相关指标。在固定期间，与等热量安慰剂相比，补充肌酸能更好地维持瘦组织质量（肌酸组增加0.9%，安慰剂组减少3.7%，p < 0.05）、肘屈肌力量（肌酸组减少4.1%，安慰剂组减少21.5%，p < 0.05）和耐力（肌酸组减少9.6%，安慰剂组减少43%，p < 0.05），以及肘伸肌力量（肌酸组减少3.8%，安慰剂组减少18%，p < 0.05）和耐力（肌酸组减少6.5%，安慰剂组减少35%，p < 0.05）。这些结果表明，短期补充肌酸可减轻年轻男性上臂固定期间肌肉质量和力量的损失。
