Rehabilitation Science Master's Program, Department of Health, Nove de Julho University, São Paulo, Brazil.
J Strength Cond Res. 2011 Jul;25(7):1795-803. doi: 10.1519/JSC.0b013e3181e501c1.
The purpose of this study was to investigate the relationships between peripheral muscle structure (mass) and function (strength, endurance, and maximal aerobic capacity) in patients with chronic obstructive pulmonary disease (COPD) with different nutritional states. Thirty-nine patients (31 male) with moderate-severe COPD (63.5 ± 7.3 [SD] years) and 17 controls (14 male; 64.7 ± 5.5 [SD] years) underwent isokinetic (peak torque [PT]), isometric (isometric torque [IT]), and endurance strength (total work [TW]) measurements of the knee extensor muscles and a maximal cardiopulmonary exercise test to evaluate the maximal aerobic capacity (peak oxygen uptake [VO(2)] peak). Muscle mass (MM) was determined using dual-energy x-ray absorptiometry. Patients with COPD presented with reduced muscle function as compared with the healthy controls: PT (105.9 ± 33.9 vs. 134.3 ± 30.9, N·m(-1), respectively, p < 0.05), TW (1,446.3 ± 550.8 vs. 1,792.9 ± 469.1 kJ, respectively, p < 0.05), and VO(2)peak (68.1 ± 15.1 vs. 93.7 ± 14.5, % pred, respectively, p < 0.05). Significant relationships were found between muscle structure and function (strength and endurance) in the patient subgroup with preserved MM and in the control group: PT·MM(r(2) = 0.36; p = 0.01 vs. r(2) = 0.32; p = 0.01, respectively) and TW·MM (r(2) = 0.32; p = 0.01 vs. r(2) = 0.22; p = 0.05, respectively). Strength corrected for mass normalized this function in both patient subgroups, whereas endurance was normalized only in the patient subgroup without muscle depletion. Maximal aerobic capacity remained reduced, despite the correction, in both patient subgroups (depleted or nondepleted) compared with the healthy controls (VO(2)peak.MM: 9.1 ± 3.7 vs. 21.8 ± 4.9 vs. 28.5 ± 4.2 ml·min·kg, respectively, with p < 0.01 among groups). Muscle atrophy seems to be the main determinant of strength reduction among patients with moderate-severe COPD, whereas endurance reduction seems to be more related to imbalance between oxygen delivery and consumption than to the local muscle structure itself. Peripheral MM did not constitute a good predictor for maximal aerobic capacity in this population. The main practical application of this study is to point out a crucial role for the strategies able to ameliorate cardiorespiratory and muscular fitness in patients with COPD, even in those patients with preserved MM.
这项研究的目的是探讨不同营养状态的慢性阻塞性肺疾病（COPD）患者外周肌肉结构（质量）与功能（力量、耐力和最大有氧能力）之间的关系。39 名中重度 COPD 患者（31 名男性；63.5 ± 7.3 [SD] 岁）和 17 名对照者（14 名男性；64.7 ± 5.5 [SD] 岁）接受了膝关节伸肌的等速（峰值扭矩 [PT]）、等长（等长扭矩 [IT]）和耐力强度（总功 [TW]）测量，以及最大心肺运动测试以评估最大有氧能力（峰值摄氧量 [VO2]峰值）。使用双能 X 线吸收法测定肌肉质量（MM）。与健康对照组相比，COPD 患者的肌肉功能降低：PT（105.9 ± 33.9 与 134.3 ± 30.9，N·m(-1)，分别，p < 0.05）、TW（1446.3 ± 550.8 与 1792.9 ± 469.1 kJ，分别，p < 0.05）和 VO2峰值（68.1 ± 15.1 与 93.7 ± 14.5，%预测值，分别，p < 0.05）。在保留 MM 的患者亚组和对照组中，肌肉结构与功能（力量和耐力）之间存在显著相关性：PT·MM（r2 = 0.36；p = 0.01 与 r2 = 0.32；p = 0.01，分别）和 TW·MM（r2 = 0.32；p = 0.01 与 r2 = 0.22；p = 0.05，分别）。在这两个患者亚组中，肌肉质量校正后的力量均使该功能正常化，而耐力仅在没有肌肉耗竭的患者亚组中正常化。与健康对照组相比，两个患者亚组（耗竭或非耗竭）的最大有氧能力仍然降低（VO2峰值.MM：9.1 ± 3.7 与 21.8 ± 4.9 与 28.5 ± 4.2 ml·min·kg，组间比较均 p < 0.01）。肌肉萎缩似乎是中重度 COPD 患者力量降低的主要决定因素，而耐力降低似乎与氧输送与消耗之间的失衡有关，而与局部肌肉结构本身关系不大。外周 MM 并不能成为该人群最大有氧能力的良好预测因子。本研究的主要实际应用是指出能够改善 COPD 患者心肺和肌肉适应性的策略具有关键作用，即使是在那些保留 MM 的患者中也是如此。
