Darnley G M, Gray A C, McClure S J, Neary P, Petrie M, McMurray J J, MacFarlane N G
Institute of Biomedical and Life Sciences, Glasgow University, Scotland, UK.
Eur J Heart Fail. 1999 Aug;1(3):297-300. doi: 10.1016/s1388-9842(99)00027-6.
Muscle weakness has been suggested to result from the deconditioning that accompanies decreased activity levels in chronic cardiopulmonary diseases. The benefits of standard exercise programmes on exercise capacity and muscular strength in disease and health are well documented and exercise capacity is a significant predictor of survival in patients with chronic heart failure (CHF). Selective respiratory muscle training has been shown to improve exercise tolerance in CHF and such observations have been cited to support the suggestion that respiratory muscle weakness contributes to a reduced exercise capacity (despite biopsies showing the metabolic profile of a well trained muscle).
This study aimed to determine the effects of selective inspiratory muscle training on patients with chronic coronary artery disease to establish if an improved exercise capacity can be obtained in patients that are not limited in their daily activities.
Nine male patients performed three exercise tests (with respiratory and diaphragm function assessed before the third test) then undertook a 4-week programme of inspiratory muscle training. Exercise tolerance, respiratory and diaphragmatic function were re-assessed after training.
Exercise capacity improved from 812+/-42 to 864+/-49 s, P<0.05, and velocity of diaphragm shortening increased (during quiet breathing from 12.8+/-1.6 to 19.4+/-1.1 mm s(-1), P<0.005, and sniffing from 71.9+/-9.4 to 110.0+/-12.3 mm s(-1), P<0.005). In addition, five from nine patients were stopped by breathlessness before training; whereas only one patient was stopped by breathlessness after training.
The major findings in this study were that a non-intensive 4-week training programme of resistive breathing in patients with chronic coronary artery disease led to an increase in exercise capacity and a decrease in dyspnoea when assessed by symptom limited exercise testing. These changes were associated with significant increases in the velocity of diaphragmatic excursions during quiet breathing and sniffing. Patients that exhibited small diaphragmatic excursions during quiet breathing were most likely to improve their exercise capacity after the training programme. However, the inspiratory muscle-training programme was not associated with any significant changes in respiratory mechanics when peak flow rate, forced expiratory volume and forced vital capacity were measured. The resistive breathing programme used here resulted in a significant increase in the velocity of diaphragm movement during quiet breathing and sniffing. In other skeletal muscles, speed of contraction can be determined by the relative proportion of fibre types and muscle length (Jones, Round, Skeletal Muscle in Health and Disease. Manchester: University Press, 1990). The intensity of the training programme used here, however, is unlikely to significantly alter muscle morphology or biochemistry. Short-term training studies have shown that there can be increases in strength and velocity of shortening that do not relate to changes in muscle biochemistry or morphology. These changes are attributed to the neural adaptations that occur early in training (Northridge et al., Br. Heart J. 1990; 64: 313-316). Independent of the mechanisms involved, this small, uncontrolled study suggests that inspiratory muscle training may improve exercise capacity, diaphragm function and symptoms of breathlessness in patients with chronic coronary artery disease even in the absence of heart failure.
有研究表明，慢性心肺疾病患者活动水平下降导致身体机能减退，进而引起肌肉无力。标准运动计划对疾病患者和健康人群运动能力及肌肉力量的益处已有充分记录，且运动能力是慢性心力衰竭（CHF）患者生存的重要预测指标。选择性呼吸肌训练已被证明可提高CHF患者的运动耐力，此类观察结果被引用来支持呼吸肌无力导致运动能力下降这一观点（尽管活检显示肌肉代谢特征良好）。
本研究旨在确定选择性吸气肌训练对慢性冠状动脉疾病患者的影响，以明确在日常活动不受限的患者中是否能提高运动能力。
9名男性患者进行了3次运动测试（在第三次测试前评估呼吸和膈肌功能），然后进行了为期4周的吸气肌训练计划。训练后重新评估运动耐力、呼吸和膈肌功能。
运动能力从812±42秒提高到864±49秒，P<0.05，膈肌缩短速度增加（安静呼吸时从12.8±1.6毫米/秒增加到19.4±1.1毫米/秒，P<0.005，吸气时从71.9±9.4毫米/秒增加到110.0±12.3毫米/秒，P<0.005）。此外，9名患者中有5名在训练前因呼吸困难而停止；而训练后只有1名患者因呼吸困难而停止。
本研究的主要发现是，对慢性冠状动脉疾病患者进行为期4周的非强化阻力呼吸训练计划，通过症状限制运动测试评估，可提高运动能力并减轻呼吸困难。这些变化与安静呼吸和吸气时膈肌运动速度的显著增加有关。安静呼吸时膈肌运动幅度小的患者在训练计划后最有可能提高运动能力。然而，在测量峰值流速、用力呼气量和用力肺活量时，吸气肌训练计划与呼吸力学的任何显著变化均无关。此处使用的阻力呼吸计划导致安静呼吸和吸气时膈肌运动速度显著增加。在其他骨骼肌中，收缩速度可由纤维类型的相对比例和肌肉长度决定（琼斯、朗德，《健康与疾病中的骨骼肌》。曼彻斯特：大学出版社，1990年）。然而，此处使用的训练计划强度不太可能显著改变肌肉形态或生物化学。短期训练研究表明，力量和缩短速度的增加可能与肌肉生物化学或形态的变化无关。这些变化归因于训练早期发生的神经适应性变化（诺思里奇等人，《英国心脏杂志》，1990年；64:313 - 316）。无论涉及何种机制，这项小型、无对照的研究表明，即使在没有心力衰竭的情况下，吸气肌训练也可能改善慢性冠状动脉疾病患者的运动能力、膈肌功能和呼吸困难症状。
