Centre for Heart, Lung and Vascular Heath, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada.
J Appl Physiol (1985). 2023 May 1;134(5):1105-1114. doi: 10.1152/japplphysiol.00303.2022. Epub 2023 Mar 9.
Skeletal muscle atrophy, dysfunction, and fatigue are important complications of chronic obstructive pulmonary disease (COPD). Greater reliance on glycolytic metabolism and increased type III/IV muscle afferent activity increase ventilatory drive, promote ventilatory constraint, amplify exertional dyspnea, and limit exercise tolerance. To investigate whether muscular adaptation with resistance training (RT) could improve exertional dyspnea, exercise tolerance, and intrinsic neuromuscular fatigability in individuals with COPD ( = 14, FEV = 62 ± 21% predicted), we performed a proof-of-concept single-arm efficacy study utilizing 4 wk of individualized lower-limb RT (3 times/wk). At baseline, dyspnea (Borg scale), ventilatory parameters, lung volumes (inspiratory capacity maneuvers), and exercise time were measured during a constant-load test (CLT) at 75% maximal workload to symptom limitation. On a separate day, fatigability was assessed using 3 min of intermittent stimulation of the quadriceps (initial output of ∼25% maximal voluntary force). Following RT, the CLT and fatigue protocols were repeated. Compared with baseline, isotime dyspnea was reduced (5.9 ± 2.4 vs. 4.5 ± 2.4 Borg units, = 0.02) and exercise time increased (437 ± 405 s vs. 606 ± 447 s, < 0.01) following RT. Isotime tidal volume increased ( = 0.01), whereas end-expiratory lung volumes ( = 0.02) and heart rate ( = 0.03) decreased. Quadriceps force, relative to initial force, was higher at the end of the stimulation protocol posttraining (53.2 ± 9.1 vs. 46.8 ± 11.9%, = 0.04). This study provides evidence that 4 wk of RT attenuates exertional dyspnea and improves exercise tolerance in individuals with COPD, which in part, is likely due to delayed ventilatory constraint and reduced intrinsic fatigability. A pulmonary rehabilitation program beginning with individualized lower-limb RT may help mitigate dyspnea before performing aerobic training in individuals with COPD. This study presents the novel finding that 4-wk resistance training (RT) focused specifically on the lower limbs can reduce exertional dyspnea during constant-load cycling, improve exercise tolerance, and reduce intrinsic fatigability of the quadriceps in individuals with COPD.
骨骼肌萎缩、功能障碍和疲劳是慢性阻塞性肺疾病（COPD）的重要并发症。糖酵解代谢的依赖性增加和 III/IV 型肌肉传入活动的增加增加了通气驱动，促进了通气限制，放大了运动性呼吸困难，并限制了运动耐量。为了研究阻力训练（RT）是否可以改善 COPD 患者的运动性呼吸困难、运动耐量和内在神经肌肉疲劳性（n = 14，FEV 为预测值的 62 ± 21%），我们进行了一项概念验证性的单臂疗效研究，利用个体化的下肢 RT（每周 3 次）进行 4 周的治疗。在基线时，在 75%最大工作负荷至症状限制的恒负荷试验（CLT）中，通过 Borg 量表测量呼吸困难、通气参数、肺容积（吸气容量试验）和运动时间。在另一天，通过 3 分钟的股四头肌间歇性刺激评估疲劳性（初始输出约为最大自主力量的 25%）。在 RT 后，重复 CLT 和疲劳方案。与基线相比，等时呼吸困难降低（5.9 ± 2.4 比 4.5 ± 2.4 Borg 单位， = 0.02），运动时间增加（437 ± 405 秒比 606 ± 447 秒， < 0.01）。等时潮气量增加（ = 0.01），而呼气末肺容积（ = 0.02）和心率（ = 0.03）降低。股四头肌力与初始力相比，在训练后刺激方案结束时更高（53.2 ± 9.1 比 46.8 ± 11.9%， = 0.04）。这项研究提供了证据，即 4 周的 RT 可以减轻 COPD 患者的运动性呼吸困难并提高运动耐量，这在一定程度上可能是由于通气限制延迟和内在疲劳性降低所致。从个体化下肢 RT 开始的肺康复计划可能有助于减轻 COPD 患者在进行有氧运动训练前的呼吸困难。这项研究的新发现是，专门针对下肢的 4 周阻力训练（RT）可以减少 COPD 患者在恒负荷自行车运动中的运动性呼吸困难，提高运动耐量，并降低股四头肌的内在疲劳性。
