Impact of inspiratory muscle training in patients with COPD: what is the evidence?

Abstract

A meta-analysis including 32 randomised controlled trials on the effects of inspiratory muscle training (IMT) in chronic obstructive pulmonary disease (COPD) patients was performed. Overall and subgroup analyses with respect to training modality (strength or endurance training, added to general exercise training) and patient characteristics were performed. Significant improvements were found in maximal inspiratory muscle strength (PI,max; +13 cmH 2 O), endurance time (+261 s), 6-or 12-min walking distance (+32 and +85 m respectively) and quality of life (+3.8 units). Dyspnoea was significantly reduced (Borg score -0.9 point; Transitional Dyspnoea Index +2.8 units). Endurance exercise capacity tended to improve, while no effects on maximal exercise capacity were found. Respiratory muscle endurance training revealed no significant effect on PI,max, functional exercise capacity and dyspnoea. IMT added to a general exercise programme improved PI,max significantly, while functional exercise capacity tended to increase in patients with inspiratory muscle weakness (PI,max ,60 cmH 2 O).IMT improves inspiratory muscle strength and endurance, functional exercise capacity, dyspnoea and quality of life. Inspiratory muscle endurance training was shown to be less effective than respiratory muscle strength training. In patients with inspiratory muscle weakness, the addition of IMT to a general exercise training program improved PI,max and tended to improve exercise performance.KEYWORDS: Meta-analysis, muscle training, respiratory muscles, systematic review R espiratory muscle weakness is observed in chronic obstructive pulmonary disease (COPD) patients [1, 2] and contributes to hypercapnia [3], dyspnoea [4,5], nocturnal oxygen desaturation [6] and reduced walking distance [7]. During exercise it has been shown that diaphragm work is increased in COPD [8] and COPD patients use a larger proportion of the maximal inspiratory pressure (PI,max) than healthy subjects [9]. This pattern of breathing is closely related to the dyspnoea sensation during exercise [9] and might potentially induce respiratory muscle fatigue. However, diaphragmatic fatigue was not demonstrated after exhaustive exercise [10]. Studies in patients with COPD have shown natural adaptations of the diaphragm to greater oxidative capacity and resistance to fatigue [11][12][13]. The abovementioned considerations gave conflicting arguments to the rationale of respiratory muscle training in COPD. Current guidelines [14,15] and meta-analyses [16][17][18][19][20] are not undisputedly positive on the application of inspiratory muscle training (IMT). From meta-analyses it is clear that IMT increases inspiratory muscle strength and endurance, and decreases dyspnoea. However, exercise performance and quality of life did not improve significantly [18,20,21]. The addition of IMT to a general exercise programme did not improve exercise performance [20]. Furthermore, differences in effects of resistance and endurance training were never analysed, while patient characte...

Effects of Inspiratory Muscle Training and Calisthenics-and-Breathing Exercises in COPD With and Without Respiratory Muscle Weakness

“…Such reductions, when of 1 point or more, are considered clinically important differences. 8 Sustained maximum inspiratory pressure Such results are consistent with previous studies, which showed that inspiratory muscle training increases abdominal mobility 10 and significantly decreases dyspnea, 30,31,34 which is paramount in patients with COPD in pulmonary rehabilitation programs.…”

“…However, a cutoff of Յ60 cm H 2 O was chosen because it is referenced for COPD. 8 It was observed that those subjects with respiratory muscle weakness had greater strength and endurance improve- It is important to emphasize that the strength gains were not clinically significant, unlike the increases in endurance. In addition, dyspnea decreased more in those subjects without muscle weakness.…”

“…However, the initial hypothesis that the specificity of the training was instrumental in the changes was confirmed, since there were higher strength and endurance gains of the inspiratory muscles in the inspiratory muscle training group when compared with the results of the calisthenics-and-breathing exercises group. This result is considered important because only in the inspiratory muscle training group we could see increases considered clinically relevant, according to the meta-analysis by Gosselink et al, 8 in which the considered increase was 13 cm H 2 O for maximum inspiratory pressure and sustained maximum inspiratory pressure and 261 s for time limit.…”

“…The cutoff value for respiratory muscle weakness was set as Յ60 cm H 2 O. 8 For variables with parametric distribution, the paired Student t test was used to analyze intragroup variance. The independent Student t test was used to compare intergroup variance.…”

“…It also occurs due to systemic factors and structural changes in those muscles, 6,7 since strength mainly depends on muscle mass, and endurance is related to muscle fiber aerobic properties. 5 In the literature, the forms of therapeutic approach to respiratory muscles are inspiratory muscle training, 8 which uses overload for such training, and calisthenics-andbreathing exercises, which are characterized by breathing exercises and stretching of respiratory muscles and/or by exercises involving the trunk and upper limbs to improve mobility of the rib cage muscles. [9][10][11][12] As for inspiratory muscle training, a meta-analysis 8 showed that it is an effective type of training for subjects with COPD, for increasing the strength and endurance of inspiratory muscles, reducing dyspnea, and improving functional capacity.…”