Muscle group III (Aδ fibres) and IV (C fibres) sensory afferents are involved in the cardiorespiratory adaptation to exercise [1, 2]. Their inhibition with intrathecal fentanyl in the dorsal horn of the spinal cord to block their cortical projections decreases high-intensity constant workload endurance performance in healthy athlete subjects because of a blunted cardiorespiratory response to exercise. In this condition with high metabolic demand, any decrease in ventilation or haemodynamics would compromise performance because of a nearly maximal solicitation without any possibility for a compensatory strategy. In contrast, Gagnon et al. [3] have published that the use of spinal anaesthesia with fentanyl with the goal of inhibiting muscle group III and IV fibres in chronic obstructive pulmonary disease (COPD) patients improved dyspnoea and endurance capacity. This improvement was due to the blunted ventilatory response to exercise which improved physiological dead space, ventilatory efficiency and in turn, dyspnoea. Moreover, at this relatively lower external workload compared with healthy subjects, cardiac output and peripheral oxygen extraction were not maximal and any mitigation in cardiac output (if any) would be overcome by an increase in peripheral muscle oxygen extraction [3]. High-frequency or low-frequency transcutaneous electrical nerve stimulation (TENS) provide a less invasive alternative which activates opioid receptors, especially those located in the dorsal horn of the spinal cord [1, 4, 5]. This approach deserves to be studied during exercise and over a course of pulmonary rehabilitation in these patients. We performed a randomised double-blind study (clinicaltrials.gov NCT03312322) to assess whether high-frequency or low-frequency lumbar TENS could improve endurance exercise capacity in patients with COPD. Secondary objectives were to assess the influence of lumbar TENS on perceived exertion, ventilatory pattern and muscle oxygenation. We hypothesised that endurance capacity would be improved with lumbar TENS due to a blunted response in exercise ventilation, which would contribute to improve ventilatory efficacy and reduce exercise dyspnoea. Conversely, we hypothesised that any mitigation in cardiac output (if any) would be compensated by an increase in peripheral muscular oxygen extraction. Lumbar transcutaneous electrical nerve stimulation aimed to block muscle group III–IV sensory afferents does not improve endurance exercise capacity in patients with COPD http://bit.ly/2lZr6Mt

中文翻译：

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腰椎经皮电神经刺激可改善 COPD 患者的运动表现

肌肉组 III（Aδ 纤维）和 IV（C 纤维）感觉传入神经参与心肺对运动的适应 [1, 2]。由于对运动的心肺反应迟钝，它们在脊髓背角鞘内注射芬太尼以阻断其皮质投射会降低健康运动员受试者的高强度恒定工作负荷耐力表现。在这种具有高代谢需求的情况下，任何通气或血液动力学的下降都会影响性能，因为几乎是最大的请求，而没有任何补偿策略的可能性。相比之下，Gagnon 等人。[3] 已经发表，使用芬太尼腰麻以抑制慢性阻塞性肺疾病 (COPD) 患者的肌肉群 III 和 IV 纤维为目标，可改善呼吸困难和耐力能力。这种改善是由于对运动的通气反应迟钝，从而改善了生理死腔、通气效率，进而改善了呼吸困难。此外，与健康受试者相比，在这种相对较低的外部工作负荷下，心输出量和外周氧提取不是最大的，心输出量的任何缓解（如果有）都将通过外周肌肉氧提取的增加来克服 [3]。高频或低频经皮神经电刺激 (TENS) 提供了一种侵入性较小的替代方案，可激活阿片受体，尤其是位于脊髓背角的那些 [1, 4, 5]。这种方法值得在这些患者的运动期间和肺康复过程中进行研究。我们进行了一项随机双盲研究 (clinicaltrials.gov NCT03312322)，以评估高频或低频腰椎 TENS 是否可以提高 COPD 患者的耐力运动能力。次要目标是评估腰椎 TENS 对感知用力、通气模式和肌肉氧合的影响。我们假设腰椎 TENS 会因运动通气反应迟钝而提高耐力能力，这将有助于提高通气效果并减少运动呼吸困难。反过来，我们假设心输出量的任何缓解（如果有的话）都可以通过增加外周肌肉氧气提取来补偿。旨在阻断肌肉群 III-IV 感觉传入的腰椎经皮电神经刺激不能提高 COPD 患者的耐力运动能力 http://bit.ly/2lZr6Mt