Department of Kinesiology, Indiana University, Bloomington, IN 47401, USA.
Med Sci Sports Exerc. 2011 Nov;43(11):2031-8. doi: 10.1249/MSS.0b013e31821f4090.
The aim of this study was to determine the effects of inspiratory muscle training (IMT) on exercise tolerance, inspiratory muscle fatigue, and the perception of dyspnea in asthmatic individuals.
Using a matched double-blind placebo-controlled design, 15 clinically diagnosed asthmatic individuals underwent either 6 wk of IMT (n = 7) consisting of 30 breaths twice daily at 50% maximum inspiratory pressure (PI max) or sham-IMT (placebo; PLA, n = 8) consisting of 60 breaths daily at 15% PI max. Time to the limit of exercise tolerance (Tlim) was assessed using constant-power output (70% peak power) cycle ergometry. Inspiratory muscle fatigue was determined by comparing the pre- to postexercise reduction in PI max. Dyspnea during the Tlim test was evaluated at 2-min intervals using the Borg CR-10 scale.
There were no significant changes (P > 0.05) in Tlim, inspiratory muscle fatigue, or perception of dyspnea in the PLA group after the intervention. In contrast, in the IMT group, PI max increased by 28%, and Tlim increased by 16% (P < 0.05). Dyspnea during exercise was also reduced significantly by 16% (P < 0.05). The exercise-induced fall in PI max was reduced from 10% before IMT to 6% after IMT (P < 0.05), despite the longer Tlim. Pulmonary function remained unchanged in both the IMT and PLA groups.
These data suggest that IMT attenuates inspiratory muscle fatigue, reduces the perception of dyspnea, and increases exercise tolerance. These findings suggest that IMT may be a helpful adjunct to asthma management that has the potential to improve participation and adherence to exercise training in this group. However, the perception of breathlessness is also an important signal of bronchoconstriction, and thus, caution should be exercised if this symptom is abnormally low.
本研究旨在确定吸气肌训练（IMT）对哮喘患者运动耐量、吸气肌疲劳和呼吸困难感知的影响。
采用匹配的双盲安慰剂对照设计，15 例临床诊断为哮喘的患者接受了 6 周的 IMT（n=7），每天 30 次，吸气压力峰值（PI max）的 50%；或假 IMT（安慰剂；PLA，n=8），每天 60 次，PI max 的 15%。通过恒定功率输出（70%峰值功率）的踏车运动评估运动耐量的极限时间（Tlim）。通过比较运动前后 PI max 的减少来确定吸气肌疲劳。在 Tlim 测试期间，每隔 2 分钟使用 Borg CR-10 量表评估呼吸困难。
在干预后，PLA 组的 Tlim、吸气肌疲劳或呼吸困难感知均无显著变化（P>0.05）。相比之下，在 IMT 组中，PI max 增加了 28%，Tlim 增加了 16%（P<0.05）。运动时的呼吸困难也显著降低了 16%（P<0.05）。尽管 Tlim 延长，但运动引起的 PI max 下降从 IMT 前的 10%减少到 IMT 后的 6%（P<0.05）。在 IMT 和 PLA 组中，肺功能均无变化。
这些数据表明，IMT 可减轻吸气肌疲劳、降低呼吸困难感知，并提高运动耐量。这些发现表明，IMT 可能是哮喘管理的有益辅助手段，有可能提高该人群对运动训练的参与度和依从性。然而，呼吸困难的感觉也是支气管收缩的一个重要信号，如果这个症状异常低，应谨慎处理。
