The main debilitating symptom of cardio respiratory disease is dyspnoea (breathlessness), but dyspnoea is also a common symptom in other conditions, and in all cases, it has a profoundly impairing influence upon quality of life and independence.
Dyspnoea is a complex phenomenon with a multifactoral origin that incorporates inputs from chemoreceptors and the cortical areas of the brain. Although the aetiology of dyspnoea may differ widely between pathologies, there is one common input to all forms of dyspnoea, including that associated with the healthy perception of breathing during exercise. This input arises from the sense of effort associated with the action of the inspiratory muscles (McConnell & Romer, 2004a).
The magnitude of the breathing effort and dyspnoea is proportional to the magnitude of the motor drive to the inspiratory muscles. The weaker a muscle is, or the greater the impedance it must overcome, the higher is the motor drive required to bring about a given action, and vice versa. Accordingly, strengthening the inspiratory muscles has a universally beneficial effect upon motor drive and dyspnoea. Thus, irrespective of its pathophysiological origin, dyspnoea can be ameliorated by specific strength training of the inspiratory muscles. Interestingly, the presence of weakness is not a pre-requisite for this effect, as inspiratory muscle training has been shown to reduce breathing effort in healthy young athletes (McConnell & Romer, 2004b), as well as patients.

Reduced inspiratory muscle strength is common in people with chronic obstructive pulmonary disease (COPD) and is associated with dyspnea and decreased exercise capacity. Most studies of inspiratory muscle training (IMT) in COPD have demonstrated increased inspiratory muscle strength. Many have also shown improvements in dyspnea and exercise capacity. However, a persisting challenge when translating and applying the findings of these studies in clinical practice is the disparity in training loads, modalities, and outcomes measures used in the different studies. This commentary summarizes our clinical and research experience with a threshold IMT device with the aim of providing clinicians interested in prescribing IMT in this population with practical recommendations regarding patient selection, assessment, and implementation of training. We propose using an interval-based high-intensity threshold IMT program for people who are unable to participate fully in whole-body exercise training because of comorbidities such as severe musculoskeletal problems. Initial training loads equivalent to at least 30% of a person's maximum inspiratory pressure (PImax) are required for all people undertaking IMT. Supervision, which includes monitoring of oxygen saturation throughout the first training session, is recommended, and patients are warned to expect transient delayed-onset muscle soreness, a consequence of muscle adaptation to an unaccustomed activity. We recommend training be undertaken 3 times a week for 8 weeks, with loads progressively increased as symptoms permit. It is prudent to exclude people at risk of pneumothorax or spontaneous rib fracture. Evaluation of IMT should include measures of PImax, dyspnea, health-related quality of life, and exercise capacity.
PMID: 20801269 DOI: 10.1016/j.apmr.2010.06.010

Brief Summary: The improvement in inspiratory muscle function might result in beneficial changes in breathing pattern during whole body exercise. The hypothesis is the effect of inspiratory muscle training as an adjunct to a pulmonary rehabilitation program improves the breathing pattern during an incremental cycle exercise.

Brief Summary: Obstructive sleep apnea (OSA) syndrome affects up to 5% of the general population. The prevalence is multiplied by 13 in coronary artery disease (CAD) patients. Many studies have shown that OSA syndrome was the main risk factor for cardiovascular morbidity and mortality (RR = 9.1 [95%, 2.6 to 31.2]).
If the value of treatment with Continuous Positive Airway Pressure (CPAP) in symptomatic CAD patients (daytime sleepiness and/or 2 clinical symptoms with Apnea Hypopnea Index (AHI) ≥ 20) appears to be established, treatment with CPAP in asymptomatic CAD patients (with AHI> 30) may be too demanding. Alternative treatments are rare and results are highly variable. Therefore, it would be interesting to suggest other treatment modalities with moderate coronary and/or minimally symptomatic OSA syndrome.
Detailed Description: This study aims to assess the relevance of inspiratory muscles strengthening on reducing AHI in CAD patients with moderate OSA (AHI between 15 and 30).

BACKGROUND: In some people with asthma, expiratory airflow limitation, premature closure of small airways, activity of inspiratory muscles at the end of expiration and reduced pulmonary compliance may lead to lung hyperinflation. With the increase in lung volume, chest wall geometry is modified, shortening the inspiratory muscles and leaving them at a sub-optimal position in their length-tension relationship. Thus, the capacity of these muscles to generate tension is reduced. An increase in cross-sectional area of the inspiratory muscles caused by hypertrophy could offset the functional weakening induced by hyperinflation. Previous studies have shown that inspiratory muscle training promotes diaphragm hypertrophy in healthy people and patients with chronic heart failure, and increases the proportion of type I fibres and the size of type II fibres of the external intercostal muscles in patients with chronic obstructive pulmonary disease. However, its effects on clinical outcomes in patients with asthma are unclear.
OBJECTIVES: To evaluate the efficacy of inspiratory muscle training with either an external resistive device or threshold loading in people with asthma.
SEARCH METHODS: We searched the Cochrane Airways Group Specialised Register of trials, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov and reference lists of included studies. The latest search was performed in November 2012.
SELECTION CRITERIA: We included randomised controlled trials that involved the use of an external inspiratory muscle training device versus a control (sham or no inspiratory training device) in people with stable asthma.
DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by The Cochrane Collaboration.
MAIN RESULTS: We included five studies involving 113 adults. Participants in four studies had mild to moderate asthma and the fifth study included participants independent of their asthma severity. There were substantial differences between the studies, including the training protocol, duration of training sessions (10 to 30 minutes) and duration of the intervention (3 to 25 weeks). Three clinical trials were produced by the same research group. Risk of bias in the included studies was difficult to ascertain accurately due to poor reporting of methods.The included studies showed a statistically significant increase in inspiratory muscle strength, measured by maximal inspiratory pressure (PImax) (mean difference (MD) 13.34 cmH2O, 95% CI 4.70 to 21.98, 4 studies, 84 participants, low quality evidence). Our other primary outcome, exacerbations requiring a course of oral or inhaled corticosteroids or emergency department visits, was not reported. For the secondary outcomes, results from one trial showed no statistically significant difference between the inspiratory muscle training group and the control group for maximal expiratory pressure, peak expiratory flow rate, forced expiratory volume in one second, forced vital capacity, sensation of dyspnoea and use of beta2-agonist. There were no studies describing inspiratory muscle endurance, hospital admissions or days off work or school.
AUTHORS' CONCLUSIONS: There is no conclusive evidence in this review to support or refute inspiratory muscle training for asthma. The evidence was limited by the small number of trials with few participants together with the risk of bias. More well conducted randomised controlled trials are needed. Future trials should investigate the following outcomes: lung function, exacerbation rate, asthma symptoms, hospital admissions, use of medications and days off work or school. Inspiratory muscle training should also be assessed in people with more severe asthma and conducted in children with asthma.
PMID: 24014205 DOI: 10.1002/14651858.CD003792.pub2