[Purpose] This study aimed to determine the effects of different intensities of inspiratory muscle training on the relative respiratory muscle activity in healthy adults. [Subjects and Methods] Thirteen healthy male volunteers were instructed to perform inspiratory muscle training (0%, 40%, 60%, and 80% maximal inspiratory pressure) on the basis of their individual intensities. The inspiratory muscle training was performed in random order of intensities. Surface electromyography data were collected from the right-side diaphragm, external intercostal, and sternocleidomastoid, and pulmonary functions (forced expiratory volume in 1 s, forced vital capacity, and their ratio; peak expiratory flow; and maximal inspiratory pressure) were measured. [Results] Comparison of the relative activity of the diaphragm showed significant differences between the 60% and 80% maximal inspiratory pressure intensities and baseline during inspiratory muscle training. Furthermore, significant differences were found in sternocleidomastoid relative activity between the 60% and 80% maximal inspiratory pressure intensities and baseline during inspiratory muscle training. [Conclusion] During inspiratory muscle training in the clinic, the patients were assisted (verbally or through feedback) by therapists to avoid overactivation of their accessory muscles (sternocleidomastoid). This study recommends that inspiratory muscle training be performed at an accurate and appropriate intensity through the practice of proper deep breathing.
Key words: Respiratory muscle, Inspiratory muscle training intensity, Surface electromyography
PMCID: PMC4842421 PMID: 27134409

BACKGROUND: Among neurodegenerative diseases, multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS) have a high rate of respiratory disability.
OBJECTIVES: To analyze the effects of respiratory muscle training (RMT) on ventilatory function, muscle strength and functional capacity in patients with MS or ALS.
DATA SOURCES: A systematic review and meta-analysis of randomized controlled trials (RCTs) was performed. The sources were MEDLINE, PEDro, Cochrane CENTRAL, EMBASE, and LILACS, from inception to January 2015.
STUDY SELECTION/ELIGIBILITY CRITERIA: The following were included: RCTs of patients with neurodegenerative diseases (MS or lateral ALS) who used the intervention as RMT (inspiratory/expiratory), comparison with controls who had not received RMT full time or were receiving training without load, and evaluations of ventilatory function (forced vital capacity - FVC, forced expiratory volume in one second - FEV1, maximum voluntary ventilation - MVV), respiratory muscle strength (maximal expiratory pressure/maximum inspiratory pressure - MEP/MIP) and functional capacity (6-minute walk test - 6MWT).
RESULTS: The review included nine papers, and a total of 194 patients. It was observed that RMT significantly increased at MIP (23.50cmH2O; 95% CI: 7.82 to 39.19), MEP (12.03cmH2O; 95% CI: 5.50 to 18.57) and FEV1 (0.27L; 95% CI: 0.12 to 0.42) compared to the control group, but did not differ in FVC (0.48L; 95% CI: -0.15 to 1.10) and distance in 6MWT (17.95m; 95% CI: -4.54 to 40.44).
CONCLUSION: RMT can be an adjunctive therapy in the rehabilitation of neurodegenerative diseases improving ventilatory function and respiratory strength.
PMID: 27026167 DOI: 10.1016/j.physio.2016.01.002

INTRODUCTION: Inspiratory muscle training (IMT) has been applied during pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD). However, it remains unclear if the addition of IMT to a general exercise training programme leads to additional clinically relevant improvements in patients with COPD. In this study, we will investigate whether the addition of IMT to a general exercise training programme improves 6 min walking distance, health-related quality of life, daily physical activity and inspiratory muscle function in patients with COPD with inspiratory muscle weakness.
METHODS AND ANALYSIS: Patients with COPD (n=170) with inspiratory muscle weakness (Pi,max <60 cm H2O or <50%pred) will be recruited to a multicentre randomised placebo controlled trial of IMT and allocated into one of the two groups. Patients in both groups will follow a 3 month general exercise training programme, in combination with home-based IMT. IMT will be performed with a recently developed device (POWERbreathe KH1). This device applies an inspiratory load that is provided by an electronically controlled valve (variable flow resistive load). The intervention group (n=85) will undertake an IMT programme at a high intensity (≥50% of their Pi,max), whereas the placebo group (n=85) will undertake IMT at a low training intensity (≤10% of Pi,max). Total daily IMT time for both groups will be 21 min (6 cycles of 30 breaths). Improvement in the 6 min walking distance will be the primary outcome. Inspiratory muscle function, health-related quality of life and daily physical activity will be assessed as secondary outcomes.
ETHICS AND DISSEMINATION: Ethics approval has been obtained from relevant centre committees and the study has been registered in a publicly accessible clinical trial database. The results will be easily interpretable and should immediately be communicated to healthcare providers, patients and the general public.
RESULTS: This can be incorporated into evidence-based treatment recommendations for clinical practice.
PMID: 23921069 PMCID: PMC3740252 DOI: 10.1136/bmjopen-2013-003101

Diaphragm remodeling associated with chronic obstructive pulmonary disease (COPD) consists of a fast-to-slow fiber type transformation as well as adaptations within each fiber type. To try to explain disparate findings in the literature regarding the relationship between fiber type proportions and FEV1, we obtained costal diaphragm biopsies on 40 subjects whose FEV1 ranged from 118 to 16% of the predicted normal value. First, we noted that our exponential regression model indicated that changes in FEV1 can account for 72% of the variation in the proportion of Type I fibers. Second, to assess the impact of COPD on diaphragm force generation, we measured maximal specific force generated by single permeabilized fibers prepared from the diaphragms of two patients with normal pulmonary function tests and two patients with severe COPD. We noted that fibers prepared from the diaphragms of severe COPD patients generated a lower specific force than control fibers (p < 0.001) and Type I fibers generated a lower specific force than Type II fibers (p < 0.001). Our finding of an exponential relationship between the proportion of Type I fibers and FEV1 accounts for discrepancies in the literature. Moreover, our single-fiber results suggest that COPD-associated diaphragm remodeling decreases diaphragmatic force generation by adaptations within each fiber type as well as by fiber type transformations.
PMID: 12857719 DOI: 10.1164/rccm.200209-1070OC

STUDY OBJECTIVES: This study was developed to investigate the influence of thoracic and upper-limb muscle function on 6-min walk distance (6MWD) in patients with COPD.
DESIGN: A prospective, cross-sectional study.
SETTING: The pulmonary rehabilitation center of a university hospital.
PATIENTS: Thirty-eight patients with mild to very severe COPD were evaluated.
MEASUREMENTS AND RESULTS: Pulmonary function and baseline dyspnea index (BDI) were assessed, handgrip strength, maximal inspiratory pressure (Pimax), and 6MWD were measured, and the one-repetition maximum (1RM) was determined for each of four exercises (bench press, lat pull down, leg extension, and leg press) performed on gymnasium equipment. Quality of life was assessed using the St. George Respiratory Questionnaire (SGRQ). We found statistically significant positive correlations between 6MWD and body weight (r = 0.32; p < 0.05), BDI (r = 0.50; p < 0.01), FEV(1) (r = 0.33; p < 0.05), Pimax (r = 0.53; p < 0.01), and all values of 1RM. A statistically significant negative correlation was observed between 6MWD and dyspnea at the end of the 6-min walk test (r = - 0.29; p < 0.05), as well as between 6MWD and the SGRQ activity domain (r = - 0.45; p < 0.01) and impact domain (r = - 0.34; p < 0.05) and total score (r = - 0.40; p < 0.01). Multiple regression analysis selected body weight, BDI, Pimax, and lat pull down 1RM as predictive factors for 6MWD (R(2) = 0.589).
CONCLUSIONS: The results of this study showed the importance of the skeletal musculature of the thorax and upper limbs in submaximal exercise tolerance and could open new perspectives for training programs designed to improve functional activity in COPD patients.
PMID: 16537851 DOI: 10.1378/chest.129.3.551