Inspiratory muscle training in adults with chronic obstructive pulmonary disease: a systematic review

The purpose of this study was to conduct a systematic review to determine the effect of inspiratory muscle training (IMT) on inspiratory muscle strength and endurance, exercise capacity, dyspnea and quality of life for adults with chronic obstructive pulmonary disease (COPD). A systematic review of the literature was conducted according the Cochrane Collaboration protocol using Medline and CINAHL. Nineteen of 274 extracted articles met the inclusion criteria and addressed comparisons of interest which included: IMT versus sham; IMT versus no intervention; low- versus high-intensity IMT; and two different modes of IMT. Thirteen meta-analyses were reported. Results indicate that targeted resistive or threshold IMT was associated with significant improvements in some outcomes of inspiratory muscle strength (PI(max) (cm H2O)) and endurance (Inspiratory Threshold Loading (kPa)), exercise capacity (Borg Scale for Respiratory Effort (modified Borg scale), Work Rate maximum (Watts)), and dyspnea (Transition Dyspnea Index), whereas IMT without a target or not using threshold training did not show improvement in these variables. There was no conclusive evidence regarding quality of life measures. IMT is effective for adults with COPD when using threshold or targeted devices that control or provide a target for training intensity.     

Inspiratory muscle training in adults with chronic obstructive pulmonary disease: an update of a systematic review

The purpose was to update an original systematic review to determine the effect of inspiratory muscle training (IMT) on inspiratory muscle strength and endurance, exercise capacity, dyspnea and quality of life for adults with chronic obstructive pulmonary disease (COPD). The original MEDLINE and CINAHL search to August 2003 was updated to January 2007 and EMBASE was searched from inception to January 2007. Randomized controlled trials, published in English, with adults with stable COPD, comparing IMT to sham IMT or no intervention, low versus high intensity IMT, and different modes of IMT were included. Nineteen of 274 articles in the original search met the inclusion criteria. The updated search revealed 17 additional articles; 6 met the inclusion criteria, all of which compared targeted, threshold or normocapneic hyperventilation IMT to sham IMT. An update of the sub-group analysis comparing IMT versus sham IMT was performed with 10 studies from original review and 6 from the update. Sixteen meta-analyses are reported. Results demonstrated significant improvements in inspiratory muscle strength (PI(max), PI(max) % predicted, peak inspiratory flow rate), inspiratory muscle endurance (RMET, inspiratory threshold loading, MVV), exercise capacity (Ve(max), Borg Score for Respiratory Effort, 6MWT), Transitional Dyspnea Index (focal score, functional impairment, magnitude of task, magnitude of effort), and the Chronic Respiratory Disease Questionnaire (quality of life). Results suggest that targeted, threshold or normocapneic hyperventilation IMT significantly increases inspiratory muscle strength and endurance, improves outcomes of exercise capacity and one measure of quality of life, and decreases dyspnea for adults with stable COPD.     

Inspiratory muscle training compared with other rehabilitation interventions in adults with chronic obstructive pulmonary disease: a systematic literature review and meta-analysis

The purpose of this systematic review was to determine the effect of inspiratory muscle training (IMT) (alone or combined with exercise and/or pulmonary rehabilitation) compared to other rehabilitation interventions such as: exercise, education, other breathing techniques or exercise and/or pulmonary rehabilitation among adults with chronic obstructive pulmonary disease (COPD). A systematic review of the literature on IMT and COPD was conducted according to the Cochrane Collaboration protocol. Inclusion criteria for the review included randomized controlled trials, published in English, comparing IMT or combined IMT and exercise/pulmonary rehabilitation with other rehabilitation interventions such as general exercise, education, other breathing techniques or exercise/pulmonary rehabilitation among adults with COPD. 274 articles were retrieved, and 16 met the inclusion criteria. Seven meta-analyses were performed that compared targeted or threshold IMT to exercise (n = 3) or to education (n = 4). Results showed significant improvements in inspiratory muscle strength and endurance, and in the dyspnea scale on a quality of life measure, for participants in the IMT versus education group. In other instances where meta-analyses could not be performed, a qualitative review was performed. IMT results in improved inspiratory muscle strength and endurance compared to education. Further trials are required to investigate the effect of IMT (or combined IMT) compared to other rehabilitation inventions for outcomes such as dyspnea, exercise tolerance, and quality of life.     

The effects of 1 year of specific inspiratory muscle training in patients with COPD

AIM: We assessed the long-term benefits of inspiratory muscle training (IMT) on inspiratory muscle strength, exercise capacity, the perception of dyspnea, quality of life, primary care use, and hospitalizations in patients with significant COPD. PATIENTS: Forty-two consecutive COPD patients with FEV(1) < 50% of predicted were randomized into a group that received IMT for 1 year, and a control group that received training with a very low load. RESULTS: There was a statistically significant increase in inspiratory muscle strength (at the end of the third month of training) as assessed by maximal inspiratory pressure (from 71 +/- 4.9 to 90 +/- 5.1 cm H(2)O [+/- SEM], p < 0.005) and 6-min walk distance (at the end of the third month of training; from 256 +/- 41 to 312 +/- 54 m; p < 0.005), a decrease in the mean Borg score during breathing against resistance (at the end of the ninth month of training), improvement in the health-related quality-of-life scores (at the end of the sixth month of training) in the training group but not in the control group. At the end of the training year, these changes were maintained; in addition, a decrease in primary health-care use and hospitalization days was observed. CONCLUSIONS: Our study shows that during IMT in patients with significant COPD, there is an increase in exercise capacity, improvement in quality of life, and decrease in dyspnea. Our study also provides evidence that long-term IMT can decrease the use of health services and hospitalization days.     

Exercise training increases respiratory muscle strength and exercise capacity in patients with chronic obstructive pulmonary disease and respiratory muscle weakness

BackgroundHow respiratory muscle strength influences the effectiveness of pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD) is unclear.ObjectiveTo investigate the benefits of PR in subjects with COPD according to respiratory muscle strength.MethodsNinety-seven subjects with COPD were evaluated using maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), pulmonary function tests, the cardiopulmonary exercise test (CPET), and the St. George's Respiratory Questionnaire (SGRQ). Subjects were divided into four groups: 1 (normal MIP and MEP); 2 (low MIP); 3 (low MEP); and 4 (low MIP and MEP). Subjects underwent PR for 3 months; MIP, MEP, SGRQ, and CPET were evaluated post-PR.ResultsSubjects with both poor MIP and MEP had the highest dyspnea score, lowest exercise capacity, and poorest health-related quality of life (HRQoL). PR improved exercise capacity and HRQoL in all groups, with more improvement in MIP, MEP, tidal volume (on exercise), and dyspnea (at rest) in subjects with both low MIP and MEP.ConclusionsPatients with respiratory muscle weakness had worse dyspnea, lower exercise capacity, and poorer HRQoL at baseline. Exercise training improved respiratory muscle strength with concurrent improvement of exercise capacity, HRQoL, and dyspnea score. Subjects with both poor baseline MIP and MEP showed greater benefits of PR.     

Benefits of short inspiratory muscle training on exercise capacity, dyspnea, and inspiratory fraction in COPD patients

Static lung hyperinflation has important clinical consequences in patients with chronic obstructive pulmonary disease (COPD). Given that most of these patients have respiratory and peripheral muscle weakness, dyspnea and functional exercise capacity may improve as a result of inspiratory muscle training (IMT). The present study is designed to investigate the benefits of a short outpatient program of IMT on inspiratory muscle performance, exercise capacity, perception of dyspnea, and the inspiratory fraction (IF). Thirty patients (24 males, 6 females) with significant COPD (forced expiratory volume in one second [FEV₁] = 46.21% ± 6.7% predicted, FEV₁ = 33.6% ± 8.04% predicted) were recruited for this study and had 3 months of IMT (30 minutes/day for 6 days/week) in an outpatient clinic. Following IMT, there was a statistically significant increase in inspiratory muscle performance (an increase of the maximal inspiratory pressure from 59% ± 19.1% to 79% ± 21.85% predicted; p = 0.0342), a decrease in dyspnea (from 5.8 ± 0.78 to 1.9 ± 0.57; p = 0.0001), an increase in the distance walked during the 6 minute walk test, from 245 ± 52.37 m to 302 ± 41.30 m, and finally an increase in the IF (the new prognostic factor in COPD) from 27.6 ± 9.7% to 31.4% ± 9.8%. The present study concludes that in patients with significant COPD, IMT results in improvement in performance, exercise capacity, sensation of dyspnea, and moreover an improvement in the IF prognostic factor.     

Inspiratory muscle training in patients with COPD: effect on dyspnea, exercise performance, and quality of life

OBJECTIVE: The aim of the study was to assess the effect of target-flow inspiratory muscle training (IMT) on respiratory muscle function, exercise performance, dyspnea, and health-related quality of life (HRQL) in patients with COPD. PATIENTS AND METHODS: Twenty patients with severe COPD were randomly assigned to a training group (group T) or to a control group (group C) following a double-blind procedure. Patients in group T (n = 10) trained with 60 to 70% maximal sustained inspiratory pressure (SIPmax) as a training load, and those in group C (n = 10) received no training. Group T trained at home for 30 min daily, 6 days a week for 6 months. MEASUREMENTS: The measurements performed included spirometry, SIPmax, inspiratory muscle strength, and exercise capacity, which included maximal oxygen uptake (VO(2)), and minute ventilation (VE). Exercise performance was evaluated by the distance walked in the shuttle walking test (SWT). Changes in dyspnea and HRQL also were measured. RESULTS: Results showed significant increases in SIPmax, maximal inspiratory pressure, and SWT only in group T (p < 0.003, p < 0.003, and p < 0.001, respectively), with significant differences after 6 months between the two groups (p < 0.003, p < 0.003, and p < 0.05, respectively). The levels of VO(2) and VE did not change in either group. The values for transitional dyspnea index and HRQL improved in group T at 6 months in comparison with group C (p < 0.003 and p < 0.003, respectively). CONCLUSIONS: We conclude that targeted IMT relieves dyspnea, increases the capacity to walk, and improves HRQL in COPD patients.     

Target-flow inspiratory muscle training at home and during pulmonary rehabilitation in COPD patients with a ventilatory limitation during exercise

The effects of a 10-week inspiratory muscle training (IMT) program at home were compared to IMT during a 10-week pulmonary rehabilitation program (PR) in 40 COPD patients with a ventilatory limitation of the exercise capacity. IMT was performed with a target-flow resistive device; the generated mouth pressure as well as the duty cycle were imposed. The mean age of the patients was 59, the mean FEV₁ was 48% of predicted. In the training period the inspiratory muscle strength improved in both groups to the same degree. EMG fatigability of the diaphragm improved in the PR + IMT group, but not in the IMT group. In theIMT group, the 12-min walking distance increased after the training period, but maximal workload (W_max), , and ADL scores did not change. In thePR + IMT group, however, W_max, , walking distance, and ADL scores improved significantly after the training period. Walking distance and ADL scores showed a significantly greater improvement in the PR + IMT group than in the IMT group. It is concluded that both isolated IMT and PR + IMT in COPD patients with a ventilatory limitation have a beneficial effect on inspiratory muscle strength, but PR + IMT improves the physical exercise capacity significantly more than IMT alone.     

Pulmonary rehabilitation improves heart rate variability at peak exercise,exercise capacity and health-related quality of life in chronic obstructive pulmonary disease

Objective

Patients with chronic obstructive pulmonary disease (COPD) appear to have impaired cardiac autonomic modulation with depressed heart rate variability (HRV). Pulmonary rehabilitation (PR) is recommended as an integral part of the management. However, the effect of PR on HRV at peak exercise remains unclear.

Methods

Sixty-four patients with COPD participated in a 12-week, 2 sessions-per-week, hospital-based PR program. Baseline and post-PR status were evaluated by spirometry, HRV, health-related quality of life (HRQL, St. George's Respiratory Questionnaire, SGRQ), cardiopulmonary exercise test, respiratory muscle strength, and dyspnea Borg's scale.

Results

After PR, there were significant improvements in the time and frequency domains of HRV with increased standard deviation of the normal R–R intervals, difference between adjacent normal R–R intervals within a given time minus one, high-frequency and decreased low-frequency, as well as concurrent improvements in HRQL, exercise capacity, dyspnea score, and respiratory muscle strength (all p < 0.05).

Conclusions

PR results in significant improvements in autonomic function, with concurrent improvements in HRQL and exercise capacity.     

Effect of dynamic hyperinflation on exertional dyspnea, exercise performance and quality of life in COPD

There is increasing evidence that dynamic hyperinflation (DH) have negative effects on exercise performance and quality of life in chronic obstructive pulmonary disease (COPD) patients. The aim of this study was to investigate effect of dynamic hyperinflation on exertional dyspnea, exercise performance and quality of life in patients with COPD. 72 clinically stable patients with moderate to severe COPD and 30 healthy age-matched control subjects were included in this study. Pulmonary function tests including lung volumes and maximal respiratory muscle forces, arterial blood gas analyses, evaluation of exertional dyspnea with the Borg scale, and The Saint George Respiratory Questionnaire (SGRQ, Turkish version) were performed at rest and after a 6-min walk test. We measured the change in inspiratory capacity (AlphaIC) after exercise to reflect DH. 80% of patients with COPD significantly decreased IC after exercise (DH). AlphaIC were -0.27 +/- 0.26 L in COPD and 0.8 +/- 0.17 L in controls (p= 0.001). A stepwise multiple regression analysis showed that to be a patient with COPD, Basal Dyspnea Index (BDI) and AlphaIC were the best predictors of 6 MWD (r(2)= 0.53, p< 0.001). FEV1 added an additinal 9% to the variance in 6 MWD. Exertional dyspnea (AlphaBorg) correlated with AlphaIC (r= -0.44, p= 0.0001) and BDI (r= 0.34, p= 0.02). AlphaIC significantly correlated with symptom (r= -0.36, p= 0.008), activity (r= -0.31, p= 0.03) and total scores (r= -0.30, p= 0.04) of SGRQ. Dynamic hyperinflation can often occur during exersice in patients with COPD. Extent of dynamic hyperinflation could able to explain exercise capacity limitation, exercise dyspnea, and poor quality of life in patients with COPD.     

Inspiratory muscle training in Morquio's syndrome: a case study

We reported a case of MPS IV A presented with dyspnea on exertion and respiratory muscle weakness. The patient underwent inspiratory muscle training (IMT) using threshold loading for 18 weeks. After 6 weeks of initial IMT, aerobic exercise training consisting of walking was added to the treatment program. Inspiratory muscle strength increased 70%, and 6-minute walk test (6MWT) distance increased to 47 m. With the inclusion of aerobic exercise training, additional increases in inspiratory muscle strength (7%) and 6MWT distance (26.5 m) were obtained. Exertional dyspnea improved from severe to slight after 6 weeks of IMT, and to very slight after additional 12 weeks of combined aerobic training and IMT. Health-related quality of life improved especially in social function, emotional function, vitality, and physical role. In conclusion, inspiratory muscles can be trained with the improvement of muscle strength in a patient with Morquio's syndrome.     

Effectiveness of 12‐week inspiratory muscle training with manual therapy in patients with COPD: A randomized controlled study

The benefits of inspiratory muscle training (IMT) in patients with COPD were reported. However, its effects are limited in severe COPD patients. Further researches are required in new and complementary modalities demonstrating IMT efficacy in severe COPD patients. This study aims to investigate effects of manual therapy (MT) additional over IMT on functional capacity, respiratory muscle strength, pulmonary function, dyspnea, fatigue, and quality of life in severe COPD patients. Sixty patients with COPD in GOLD stage III–IV were included in this prospective single‐blind randomized trial. Patients were randomly assigned to receive either MT additional over IMT at 40% of maximal inspiratory pressure (MIP) (n = 30) or only IMT (n = 30) for 12 weeks. MT group received MT during 12 weeks for 30 min additional to IMT. Pulmonary function, respiratory muscle strength, functional capacity, dyspnea, fatigue, and quality of life were evaluated by spirometry, mouth pressure device, six‐minute walk test, Modified Medical Research Council (mMRC) dyspnea scale, fatigue severity scale, and St. George''s Respiratory Questionnaire (SGRQ), respectively. MT group had significantly greater improvement in FEV1%, FVC%, PEF%, respiratory muscle strength, function, dyspnea, fatigue, and quality of life compared with IMT group (p < 0.05). 6MWT (p < 0.001, effect size Cohen''s d: 0.915), MIP (p < 0.001, effect size Cohen''s d: 1.235), and mMRC score (p < 0.001, effect size Cohen''s d: 0.982) were significantly improved in IMT with MT group. This study demonstrated that subjects in IMT with MT group had improved outcomes in functional capacity, respiratory muscle strength, pulmonary function, dyspnea, fatigue perception, and quality of life compared with alone IMT group.     

Respiratory muscle function and exercise intolerance in heart failure

Inspiratory muscle weakness (IMW) is prevalent in patients with chronic heart failure (CHF) caused by left ventricular systolic dysfunction, which contributes to reduced exercise capacity and the presence of dyspnea during daily activities. Inspiratory muscle strength (estimated by maximal inspiratory pressure) has independent prognostic value in CHF. Overall, the results of trials with inspiratory muscle training (IMT) indicate that this intervention improves exercise capacity and quality of life, particularly in patients with CHF and IMW. Some benefit from IMT may be accounted for by the attenuation of the inspiratory muscle metaboreflex. Moreover, IMT results in improved cardiovascular responses to exercise and to those obtained with standard aerobic training. These findings suggest that routine screening for IMW is advisable in patients with CHF, and specific IMT and/or aerobic training are of practical value in the management of these patients.     

Target-flow inspiratory muscle training during pulmonary rehabilitation in patients with COPD

The effects of additional target-flow inspiratory muscle training (TF-IMT) on the performance of the inspiratory muscles, on general exercise capacity, and on psychologic parameters during a pulmonary rehabilitation program (PR) were studied in 40 patients with COPD selected for ventilatory limitation during exercise. The mean age of the patients was 59 years, and the mean FEV1 was approximately 50 percent of predicted. All patients participated in a ten-week PR program. They were randomized to receive either additional TF-IMT (PR + IMT) or not (PR). The TF-IMT was performed by means of a target-flow resistive device; the generated mouth pressure and the duration of inspiration and of the respiratory cycle were imposed. After the training period, maximal inspiratory mouth pressure and EMG-fatigability of the diaphragm were significantly better in the PR + IMT group than in the PR group. Maximal work load and psychologic symptoms increased to the same extent in both groups. The 12-minute walking distance also increased in both groups, but it increased significantly more in the PR + IMT group than in the PR group. We believe that additional TF-IMT during PR in a selected group of patients with COPD who have ventilatory limitation has an extra beneficial effect on the performance of the inspiratory muscles and on exercise performance.     

Nutritional support and functional capacity in chronic obstructive pulmonary disease: A systematic review and meta‐analysis

Currently, there is confusion about the value of using nutritional support to treat malnutrition and improve functional outcomes in chronic obstructive pulmonary disease (COPD). This systematic review and meta‐analysis of randomized, controlled trials (RCT) aimed to clarify the effectiveness of nutritional support in improving functional outcomes in COPD. A systematic review identified 12 RCT (n = 448) in stable COPD patients investigating the effects of nutritional support (dietary advice (1 RCT), oral nutritional supplements (10 RCT), enteral tube feeding (1 RCT)) versus control on functional outcomes. Meta‐analysis of the changes induced by intervention found that while respiratory function (forced expiratory volume in 1 s, lung capacity, blood gases) was unresponsive to nutritional support, both inspiratory and expiratory muscle strength (maximal inspiratory mouth pressure +3.86 standard error (SE) 1.89 cm H₂O, P = 0.041; maximal expiratory mouth pressure +11.85 SE 5.54 cm H₂O, P = 0.032) and handgrip strength (+1.35 SE 0.69 kg, P = 0.05) were significantly improved and associated with weight gains of ≥2 kg. Nutritional support produced significant improvements in quality of life in some trials, although meta‐analysis was not possible. It also led to improved exercise performance and enhancement of exercise rehabilitation programmes. This systematic review and meta‐analysis demonstrates that nutritional support in COPD results in significant improvements in a number of clinically relevant functional outcomes, complementing a previous review showing improvements in nutritional intake and weight.     

Effects of 3-week Outpatient Pulmonary Rehabilitation on Exercise Capacity, Dyspnea, and Quality of Life in COPD

The effects of intensive 3-week outpatient pulmonary rehabilitation (PR) on exercise capacity, dyspnea, and health-related quality of life (HRQL) were investigated in patients with COPD. Two hundred ten patients with COPD (mean FEV₁ = 54%pred) underwent PR consisting of exercise training, patient and psychosocial education, breathing and relaxation therapy, nutrition counseling, and smoking cessation support. Before and after PR, exercise capacity was assessed with 6-min walking tests (6MWT) and constant cycle ergometer exercise (CEE). Dyspnea was measured after 6MWTs with a Borg scale and after PR with the Transition Dyspnoea Index (TDI). HRQL was examined with the Medical Outcomes Study Short Form 36 (SF-36). Results showed improvements in the 6MWT (+39 m, p < 0.001) and CEE (+241 W × min, p < 0.001) after PR, paralleled by decreased dyspnea during the 6MWT (−0.5, p < 0.001) and during activities (TDI score = 3.6). Increases in all SF-36 subscales reflected improved HRQL after PR (p < 0.001). No gender differences were found. Patients with milder versus more severe COPD improved similarly in most outcomes. Regression analyses revealed that TDI scores were the most important predictor of improvements in HRQL. The results suggest that intensive 3-week outpatient PR is associated with improvements in exercise capacity, dyspnea, and HRQL in male and female patients with COPD irrespective of COPD severity. Reduced dyspnea during activities contributed the most to improvements in HRQL.     

Cycle ergometer and inspiratory muscle training in chronic obstructive pulmonary disease.

In patients with chronic obstructive pulmonary disease (COPD) the intensity of aerobic training is limited by dyspnea. Improving strength of the inspiratory muscles could enhance aerobic exercise training by reducing exercise-related dyspnea. We examined effects of home-based inspiratory muscle training (IMT) and cycle ergometry training (CET) in 53 patients with moderate to severe COPD (FEV(1)% pred, 50 +/- 17 [mean +/- SD]). Patients were randomly assigned to 4 mo of training in one of four groups: IMT, CET, CET + IMT, or health education (ED). Patients were encouraged to train to the limits of their dyspnea. Inspiratory muscle strength and endurance increased in IMT and CET + IMT groups compared with CET and ED groups (p < 0. 01). Peak oxygen uptake increased and heart rate, minute ventilation, dyspnea, and leg fatigue decreased at submaximal work rates in the CET and CET + IMT groups compared with the IMT and ED groups (p < 0. 01). There were no differences between the CET and CET + IMT groups. Home-based CET produced a physiological training effect and reduced exercise-related symptoms while IMT increased respiratory muscle strength and endurance. The combination of CET and IMT did not produce additional benefits in exercise performance and exercise-related symptoms. This is the first study to demonstrate a physiological training effect with home-based exercise training.     

Creatine supplementation for patients with COPD receiving pulmonary rehabilitation: A systematic review and meta‐analysis

Background and objective: Creatine improves muscle strength in exercising healthy individuals, and in patients with neuromuscular disease and heart failure. The aim of this study was to assess whether creatine supplementation improves pulmonary rehabilitation (PR) outcomes in patients with COPD. Methods: A systematic review and meta‐analysis was performed of randomized controlled trials published between January 1966 and February 2009 that evaluated the effect of creatine compared with placebo on exercise capacity, muscle strength and health‐related quality of life (HR‐QoL) in patients undergoing PR for COPD. The pooled estimates were expressed as mean differences (MD) or standardized mean differences (SMD). Results: Four randomized controlled trials that included 151 patients were identified. There was no effect of creatine supplementation on exercise capacity (SMD ?0.01, 95% CI: ?0.42 to 0.22, n = 151). Creatine supplementation did not improve lower extremity muscle strength (SMD 0.03, 95% CI: ?0.55 to 0.61, n = 140) or upper limb muscular strength (SMD 0.02, 95% CI: ?0.33 to 0.38, n = 128) compared with placebo. Two studies (n = 48) assessed quality of life using the St. George's Respiratory Disease Questionnaire. There were no differences in HR‐QoL according to domain or total scores. Overall, creatine appeared to be safe and was well tolerated. Quality assessment of the studies showed important limitations. Conclusions: Creatine supplementation does not improve exercise capacity, muscle strength or HR‐QoL in patients with COPD receiving PR. However, important limitations were identified in the quality of the available evidence, suggesting that further research is required in this area.     

The role of inspiratory muscle function and training in the genesis of dyspnoea in asthma and COPD.

The cardinal symptom of both asthma and COPD is dyspnoea, and from a patient perspective, the most troublesome. There are a multitude of inputs to the sensation of dyspnoea, few of which are readily modifiable. The level of inspiratory muscle work contributes to the sense of respiratory muscle effort and thence dyspnoea. Inspiratory muscle work is elevated in patients with COPD and asthma due to hyperinflation and an increased ventilatory requirement for exercise. Treatment tends to concentrate on reducing the load upon the inspiratory muscles induced by hyperinflation. Bronchodilators are the mainstay of treatment for COPD and asthma; they reduce hyperinflation, inspiratory muscle loading and dyspnoea. In addition, programmes of pulmonary rehabilitation have an excellent evidence base for improving dyspnoea, exercise tolerance and quality of life. However, provision within the NHS is limited and not all patients are suitable. One component of pulmonary rehabilitation that can be implemented safely in a home-based setting is specific inspiratory muscle training (IMT). There is a strong theoretical rationale for IMT in patients with airway obstruction, which is also supported by empirical evidence. IMT offers a relatively accessible non-pharmacological treatment for dyspnoea that also improves exercise tolerance and quality of life.     

Maintenance of inspiratory muscle training in COPD patients: one year follow-up.

In most chronic obstructive pulmonary disease (COPD) patients, dyspnoea and functional exercise capacity may improve as a result of inspiratory muscle training (IMT). However, the long-term benefits of IMT have been investigated to a much lesser extent. The present study investigated the short-term and long-term benefits of IMT on inspiratory muscle performance (strength and endurance), exercise capacity and the perception of dyspnoea. Thirty-eight patients with significant COPD had 3 months of basic IMT and were then randomised into a group that received maintenance IMT for the next year, and a group that got training with very low load. Following the basic training there was a statistically significant increase in inspiratory muscle performance, 6-min walk test (6MWT), and a decrease in the dyspnoea. During the second stage of the study, the training group continued to maintain the improvement in all parameters, while there was already deterioration in the inspiratory muscle performance, exercise capacity and dyspnoea in the low intensity group during the 6-12 month period. The present study concludes that, in patients with significant chronic obstructive pulmonary disease, inspiratory muscle training results in improvement in performance, exercise capacity and in the sensation of dyspnoea. The benefits of 12-weeks of inspiratory muscle training decline gradually over 1 yr of follow-up if maintenance training is not performed.