Inspiratory Muscle Training Research Articles

Impacts of three inspiratory muscle training programs on inspiratory muscles strength and endurance among intubated and mechanically ventilated patients with difficult weaning: a multicentre randomised controlled trial

BackgroundInspiratory muscle training (IMT) is well-established as a safe option for combating inspiratory muscles weakness in the intensive care setting. It could improve inspiratory muscle strength and decrease weaning duration but a lack of knowledge on the optimal training regimen raise to inconsistent results. We made the hypothesis that an innovative mixed intensity program for both endurance and strength improvement could be more effective. We conducted a multicentre randomised controlled parallel trial comparing the impacts of three IMT protocols (low, high, and mixed intensity) on inspiratory muscle strength and endurance among difficult-to-wean patients.MethodsNinety-two patients were randomly assigned to three groups with different training programs, where each performed an IMT program twice daily, 7 days per week, from inclusion until successful extubation or 30 days. The primary outcome was maximal inspiratory pressure (MIP) increase. Secondary outcomes included peak pressure (Ppk) increase as an endurance marker, mechanical ventilation (MV) duration, ICU length of stay, weaning success defined by a 2-day ventilator-free after extubation, reintubation rate and safety.ResultsMIP increases were 10.8 ± 11.9 cmH2O, 4.5 ± 14.8 cmH2O, and 6.7 ± 14.5 cmH2O for the mixed intensity (MI), low intensity (LI), and high intensity (HI) groups, respectively. There was a non-statistically difference between the MI and LI groups (mean adjusted difference: 6.59, 97.5% CI [− 14.36; 1.18], p = 0.056); there was no difference between the MI and HI groups (mean adjusted difference: − 3.52, 97.5% CI [− 11.57; 4.53], p = 0.321). No significant differences in Ppk increase were observed among the three groups. Weaning success rate observed in MI, HI and LI group were 83.7% [95% CI 69.3; 93.2], 82.6% [95% CI 61.2; 95.0] and 73.9% [95% CI 51.6; 89.8], respectively. MV duration, ICU length of stay and reintubation rate had similar values. Over 629 IMT sessions, six adverse events including four spontaneously reversible bradycardia in LI group were possibly related to the study.ConclusionsAmong difficult-to-wean patients receiving invasive MV, no statistically difference was observed in strength and endurance progression across three different IMT programs. IMT appears to be feasible in usual cares, but some serious adverse events such as bradycardia could motivate further research on the specific impact on cardiac system.Trial registration Clinicaltrials.gov identifier: NCT02855619. Registered 28 September 2014

Effect of inspiratory muscle training in esophageal cancer patients receiving esophagectomy: A meta-analysis of randomized controlled trials.

To identify the clinical effect of inspiratory muscle training (IMT) among esophageal cancer patients undergoing esophagectomy based on randomized controlled trials (RCTs). Several databases were searched for relevant RCTs up to August 23, 2023. Primary outcomes were respiratory muscle function, including the maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP), and pulmonary function, including the forced expiratory volume in one second % (FEV1%), forced vital capacity% (FVC%), maximal ventilator volume (MVV), FEV1/FVC% and FVC. The secondary outcomes were exercise performance, including the six-minute walk distance test (6MWT) and Borg index; mental function and quality of life, as evaluated by the Hospital Anxiety Depression Scale (HADS) and Nottingham Health Profile (NHP) score; and postoperative complications. All the statistical analyses were performed with REVMAN 5.3 software. Eight RCTs were included in this meta-analysis, with 368 patients receiving IMT and 371 control subjects. The pooled results demonstrated that IMT could significantly enhance respiratory muscle function (MIP: MD = 7.14 cmH2O, P = 0.006; MEP: MD = 8.15 cmH2O, P<0.001) and pulmonary function (FEV1%: MD = 6.15%, P<0.001; FVC%: MD = 4.65%, P<0.001; MVV: MD = 8.66 L, P<0.001; FEV1/FVC%: MD = 5.27%, P = 0.03; FVC: MD = 0.50 L, P<0.001). Furthermore, IMT improved exercise performance (6MWT: MD = 66.99 m, P = 0.02; Borg index: MD = -1.09, P<0.001), mental function and quality of life (HADS anxiety score: MD = -2.26, P<0.001; HADS depression score: MD = -1.34, P<0.001; NHP total score: MD = -48.76, P<0.001). However, IMT did not significantly decrease the incidence of postoperative complications. IMT improves clinical outcomes, such as respiratory muscle function and pulmonary function, in esophageal cancer patients receiving esophagectomy and has potential for broad applications in the clinic.

Effectiveness of simultaneous bilateral visual diaphragm biofeedback under low back pain: influence of age and sex.

Introduction: The aim of the present study was to determine the effectiveness of simultaneous bilateral visual diaphragm biofeedback (BFB) from ultrasonography in conjunction with inspiratory muscle training (IMT) on diaphragmatic thickness during normal breathing and respiratory and clinical outcomes in patients with non-specific low back pain (NSLBP) and determine the influence of age and sex. Methods: A single-blind randomized clinical trial was carried out (NCT04582812). A total sample of 96 patients with NSLBP was recruited and randomized by sex-based stratification into IMT (n = 48) and BFB + IMT (n = 48) interventions over 8weeks. Bilateral diaphragmatic thickness at maximum inspiration (Tins) and expiration (Texp), respiratory pressures, lung function, pain intensity, bilateral pressure pain threshold (PPT), disability, and quality of life were measured at baseline and after 8weeks. Results: The BFB + IMT group showed significant differences (p < 0.05) with increased left hemidiaphragm thickness at Tins and Tins-exp (d = 0.38-053), and right and left PPT (d = 0.71-0.74) versus the IMT group. The interaction with sex was statistically significant (p = 0.007; F(1,81) = 7.756; ηp 2 = 0.087) and higher left hemidiaphragm thickness at Tins was predicted by the BFB + IMT group (R 2 = 0.099; β = 0.050; F(1,82) = 8.997; p = 0.004) and male sex (R 2 = 0.079; β = 0.045; F(1,81) = 7.756;p = 0.007). Furthermore, greater left hemidiaphragm thickness at Tins-exp was predicted by younger age (R 2 = 0.052; β = -0.001; F(1,82) = 4.540; p = 0.036). Discussion: The simultaneous bilateral visual diaphragm biofeedback by ultrasonography in conjunction with IMT was effective in both increasing the left diaphragmatic thickness during inspiration, which was positively influenced and predicted by male sex and younger age, and increasing the bilateral PPT of the paraspinal muscles in patients with NSLBP.

Inspiratory Muscle Training for Lung Transplant Candidates and Recipients.

Inspiratory muscle training is used in rehabilitation to exercise respiratory muscles in various conditions associated with limited ventilatory reserve. In this review, we investigated inspiratory muscle training in lung transplant candidates and recipients. We searched 5 primary databases from inception through April 2024. Two key word entries, "lung transplantation" and "inspiratory muscle training," were matched using the Boolean operator AND. No filters were applied for document type, age, sex, publication date, language, and subject. The searched databases returned 119 citations. Seven articles that considered 64 patients (47% female) were included in the final analysis, with 1 study involving a pediatric patient. Lung transplant recipients used a threshold trainer at 15% to 60% of maximal inspiratory pressure and mostly exercised twice daily for 10 to 15 minutes per session. Lung transplant candidates exercised at 30% to >50% of maximal inspiratory pressure twice daily, performing 30 to 60 inspirations or for 15 minutes. The highest inspiratory muscle strength was observed in a series of adult lung transplant recipients whose mean value improved by 31.8 ± 14.6 cmH2O versus baseline after treatment. To the same extent, the highest value of maximal inspiratory pressure was detected in a pediatric patient who scored 180 cmH2O after training. Overall, participants obtained improvements in lung function (forced expiratory volume in 1 second, forced vital capacity), functional performance, dyspnea intensity, and exercise tolerance. Inspiratory muscle training is easy to perform and can be done at home without specific supervision (in adults) before or after a lung transplant. Nevertheless, additional rigorous investigations should aim to replicate the positive effects reported in the present review.

Updates in inspiratory muscle training for older adults: A systematic review

Systematic reviews support the benefits of inspiratory muscle training (IMT) for exercise performance. Recently, many health benefits from IMT have been reported in older adults. Therefore, this work reviewed the literature focusing on IMT effects beyond physical performance in older adults, such as cardiorespiratory, metabolic, and postural balance outcomes. Searches were conducted with the following terms: ("respiratory muscle training" OR "inspiratory muscle training") OR ("inspiratory muscle strength training") AND ("elderly" OR "older" OR "aging" OR "aging"), and using the databases: MEDLINE (PubMed), SCOPUS and EUROPE PMC. Of the 356 articles found, 13 matched the inclusion criteria after screening. Based on reviewed studies, four to eight weeks of IMT (Mostly from 50 % up to 75 % of MIP, 7 days/week) improve cardiac autonomic control at rest and post-exercise, cerebrovascular response to orthostatic stress, static and dynamic balance, blood pressure control, endothelial function, and oxidative stress in older adults. The benefits of IMT in cardiac autonomic and vascular functions are reversed after training cessation. It thus appears that IMT promotes broad physiological gains for the older population. It is necessary to carry out more randomized clinical trials on the subject to confirm the findings of this research.

Pulmonary Hypertension: Exercise Intolerance and the Benefits of Respiratory Muscle and Exercise Training

Pulmonary hypertension is characterized by significant remodeling of the pulmonary vasculature, leading to raised pulmonary vascular resistance. Despite advances in medical therapy, decreased exercise tolerance remains a predominant symptom experienced by patients. Reduced exercise capacity has been shown to have implications on quality of life and prognosis. There is growing acknowledgment that the etiology of exercise tolerance is multifactorial with cardiac, respiratory, and skeletal muscle contributors. There has been a shift in management approach with exercise training now included as a Class 1 recommendation indication in recent guidelines. In this review, we summarize the literature on the pathophysiology of exercise intolerance in pulmonary hypertension and then describe the literature assessing the safety and efficacy of inspiratory muscle and exercise training in patients with pulmonary arterial hypertension or chronic thromboembolic pulmonary hypertension.

Inspiratory Muscle Training and Its Potential Benefits on Athlete Performance

Inspiratory Muscle Training and Its Potential Benefits on Athlete Performance

“Effects of threshold respiratory muscle training on respiratory muscle strength, pulmonary function and exercise endurance after stroke: a meta-analysis”

BackgroundMost studies on improvements in respiratory muscle strength, activities of daily living (ADL) and quality of life (QoL) in stroke patients receiving threshold respiratory muscle training (TRMT) have small sample sizes, and some studies have contradictory results. ObjectivesTo evaluate the effectiveness of TRMT on respiratory muscle strength, pulmonary function and exercise endurance in stroke patients. Materials and MethodsPubMed, Cochrane Library, Physical Therapy Evidence Database (PEDro), Embase (via OVID) and Web of Science databases were searched for randomized controlled trial (RCT) from inception to January 17, 2024. The primary outcome was maximum inspiratory pressure (MIP) or maximum expiratory pressure (MEP). Secondary outcomes included pulmonary function measured by forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and peak expiratory flow (PEF), and exercise endurance measured by 6-minute walk test (6MWT). ResultsA total of eight randomized controlled trials(RCTs), including 305 persons, were included in this study. The training time ranged from 3 weeks to 10 weeks. Among them, the intervention group in 4 studies used inspiratory muscle training, and the other 4 studies used inspiratory muscle training and expiratory muscle training. For the primary outcome, TRMT significantly improved MIP (mean=14.68 cmH2O, 95 %CI=2.28 to 27.09 cmH2O, P=0.02) and MEP (mean=9.37 cmH2O, 95 %CI=2.89 to 15.84 cmH2O, P=0.005) in stroke patients. Regarding the secondary outcomes, TRMT improved FVC, FEV1 and 6MWT (P<0.05) but did not significantly improve PEF. ConclusionTRMT improved inspiratory muscle strength and expiratory muscle strength, improved exercise endurance, and improved FVC and FEV1 of pulmonary function but did not significantly improve PEF.

Effects of Cardiopulmonary Rehabilitation on Cardiorespiratory Fitness and Clinical Symptom Burden in Long COVID: Results from the COVID-Rehab Randomized Controlled Trial.

To investigate the effectiveness of an eight-week cardiopulmonary rehabilitation program on cardiorespiratory fitness (VO2peak) and key cardiopulmonary exercise test measures, quality of life, and symptom burden in individuals with Long COVID. Forty individuals with Long COVID (mean age 53 ± 11 years), were randomized into 2 groups: 1/ Rehabilitation group: centre-based individualized clinical rehabilitation program (8 weeks, 3 sessions per week of aerobic and resistance exercises, and daily inspiratory muscle training) and 2/ Control group: individuals maintained their daily habits during an eight-week period. There was a significant difference between groups in mean VO2peak improvement (p = 0.003). VO2peak improved significantly in the rehab group (+2.7 mL.kg.min 95%IC:+1.6 to +3.8 p < 0.001) compared to the control group (+0.3 mL.kg.min 95%IC:-0.8 to +1.3 p = 0.596), along withVE/VCO2 slope (p = 0.032) (-2.4 95%IC:-4.8 to +0.01 p = 0.049 and + 1.3 95%IC:-1.0 to +3.6 p = 0.272 respectively) and VO2 at first ventilatory threshold (p = 0.045). Furthermore, all symptom impact scales improved significantly in the rehabilitation group compared to the control group (p < 0.05). An individualized and supervised cardiopulmonary rehabilitation program was effective in improving cardiorespiratory fitness, ventilatory efficiency, and symptom burden in individuals with Long COVID. Careful monitoring of symptoms is important to appropriately tailor and adjust rehabilitation sessions.

Enhanced diaphragm excursion and exercise tolerance in COPD patients through inspiratory muscle training after standardised pulmonary rehabilitation: randomised controlled trial

ObjectiveInspiratory muscle training (IMT) is used to improve inspiratory muscle strength in patients with chronic obstructive pulmonary disease (COPD). However, the effect of IMT on diaphragmatic function has not yet been thoroughly evaluated. This study aimed to evaluate the effect of IMT on maximum diaphragmatic excursion (DEmax) using ultrasonography in patients with COPD.MethodsThis was a single-center, randomised, prospective, parallel-group, unblinded controlled trial involving 38 participants with stable COPD. Participants underwent a standardised 12-week pulmonary rehabilitation (PR) program followed by a 12-week IMT program, consisting of home-based IMT and low-frequency outpatient PR sessions supervised by physiotherapists (once every 2 weeks),versuslow-frequency outpatient PR alone as a control. The DEmaxand exercise tolerance were measured.ResultsOut of the 38 patients initially enrolled in the PR program, 33 successfully completed it and were subsequently randomised to the IMT program. Finally, 15 (94%) and 14 (88%) patients from the IMT and control groups, respectively, completed the study. Following the IMT program, DEmaxincreased in the IMT group (50.1±7.6 mm to 60.6±8.0 mm, p&lt;0.001), but not in the control group (47.4±7.9 mm to 46.9±8.3 mm, p=0.10). Changes in DEmaxand exercise tolerance (peak VO2) were greater in the IMT group than in the control group (both p&lt;0.01).ConclusionsIMT following the PR program improved DEmaxand exercise tolerance. Therefore, DEmaxmay be an important outcome of IMT.

Comparing effects of inspiratory muscle trainer and lung flute on sputum clearance in chronic obstructive pulmonary disease: A randomized controlled trial

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease. Mucus accumulation, a common impairment in COPD affects lung function, exacerbations and quality of life. Physiotherapy measures including positive expiratory pressure devices like lung flute form the non-pharmacologic treatment options for the same. Although not a primary airway clearance device, inspiratory muscle trainer (IMT) plays a role in it. The aim of this study was to compare the effectiveness of lung flute and IMT as methods for sputum clearance in COPD. METHOD: Participants with COPD were recruited from the Department of Pulmonology and screened for eligibility. Block randomization was used to divide the participants into three groups: Inspiratory muscle training (IMT), lung flute (LF), and routine physiotherapy (RP). Supervised 30 minutes of in-patient intervention was delivered to all the groups for 6 days, once a day. Total sputum volume analysis (TSV) was conducted before and after 6 days of intervention. Descriptive statistics were presented as median and quartiles. Kruskal Wallis H test and Wilcoxon signed rank test were applied. RESULTS: 60 participants aged 55 to 65 years with mild to moderate COPD were included in the study. Median TSV for RP, LF and IMT were 8.50, 20.50 and 25.75 ml respectively. Pair-wised comparisons for TSV revealed significant differences for the means of the rank scores between RP and LF (LF dominant) (p &lt; 0.001), RP and IMT (IMT dominant) (p &lt; 0.001) and LF and IMT (IMT dominant) (p = 0.002). CONCLUSION: IMT performed superiorly in terms of sputum clearance in patients with COPD.

Evaluation of Preoperative Breathing Techniques on Functional Mobility in On-Pump Versus Off-Pump Coronary Artery Bypass Graft Patients: A Comprehensive Review

This review investigates and contrasts the effects of various preoperative chest rehabilitation techniques in patients undergoing coronary artery bypass graft (CABG) surgery, both on-pump and off-pump. Utilizing databases such as Pedro, Cochrane, and PubMed, a comprehensive literature review was conducted, focusing on studies published between 2017 and 2023. We identified 14 relevant articles that met specific inclusion and exclusion criteria, examining the effects of preoperative physiotherapy in adult patients undergoing CABG surgery. Preoperative physiotherapy encompasses a variety of approaches, including counseling, cardiovascular exercise, instruction on breathing techniques, and inspiratory muscle training (IMT). Numerous studies have highlighted the benefits of integrating these methods, such as reducing the risk of postoperative pulmonary complications, shortening hospital stays, achieving earlier extubation, and decreasing anxiety. Despite these findings, further research is needed to evaluate the effectiveness of combination therapies, particularly those involving IMT, in preoperative physical therapy. The goal is to develop a comprehensive understanding of the mechanisms through which these treatments reduce pulmonary complications post-surgery.

The role of inspiratory muscle fatigue and its impact on strength and respiratory function

Inspiratory muscles are essential for breathing and during exercise. However, excessive effort on the respiratory system can cause the inspiratory muscles, such as the external intercostals and the diaphragm, to become fatigued, therefore impairing performance (Wuthrich et al., 2013, Exp Physiol, 12, 1705–1717). Inspiratory muscle fatigue is when there is a loss in the capacity to produce force and/or velocity in a muscle, meaning they become tired and weak due to increased work demands (Tsukamoto et al., 2019, J Phys Ther Sci, 31, 318–325). Inspiratory muscle fatigue impacts performance because the force produced by the inspiratory muscles starts to decline which therefore causes them to fatigue as they cannot work to the maximum capacity no longer. This is vital in aerobic exercises such as rowing, cycling and running as the demand for oxygen is higher to perform the tasks. The diaphragm is the most dominant respiratory muscle involved in inspiration, alongside the external intercostal muscles. During inspiration, the diaphragm contracts and flattens, and the external intercostal muscles contract, pulling the ribcage up and outwards. The main function of these muscles is to allow a maximum amount of oxygen into the lungs by increasing the surface area in the thoracic cavity (Siafakas et al., 1999, Thorax, 54, 458–465). Several studies have explored delaying muscle fatigue by using inspiratory muscle training in healthy individuals. This is because it improves the strength of the respiratory muscles by increasing the endurance and capacity of the diaphragm. Results highlighted that maximum inspiratory pressure increased between 16 and 18% (Segizbaeva et al., 2014, Hum Physiol, 40, 683-689), a 7% increase in inspiratory muscle strength (Smith et al., 2021, Am J Physiol, 312, 1013-1018), a delay in muscle fatigue, and an improvement in performance. There is limited research on cycling, rowing, and running; therefore, this study aims to determine whether any of these exercises delay or increase muscle fatigue and to determine if maximal inspiratory pressure and maximal expiratory pressure improve respiratory function. This study aims to recruit 9–12 participants, which will involve four visits to the laboratory. Exercises include a 10-kilometre cycling session, a 3-kilometre treadmill running session, and a 2-kilometre rowing session, and these will be done in a randomised order. Visit 1 includes familiarisation; visit 2 involves baseline measures being recorded and test 1 being conducted; visit 3 includes test 2 being administered; and visit 4 involves test 3 being conducted. The measurements that will be collected at each kilometre are heart rate, rate of perceived exertion, and dyspnea. Blood lactate, maximal inspiratory pressure, and maximum expiratory pressure, however, will be collected before and after each test. At this present time, results are pending. My hypothesis for this study would be that all the cardio-based exercises will see an improvement in respiratory function and strength, with treadmill running having the biggest improvement as, throughout the 4 weeks, adaptation would have occurred.

Effect of Inspiratory Muscle Training on Cough Strength in Older People With Frailty: A Single-Blind Randomized Controlled Trial

ObjectiveTo investigate the effect of inspiratory muscle training (IMT) on cough strength in older people with frailty. DesignSingle-blind randomized controlled trial. SettingDay health care centers at 2 sites. ParticipantsOlder people with frailty (N=60). InterventionsEligible people were randomly assigned to receive IMT program in addition to general exercise training (IMT group), or general exercise training alone (control group). The IMT group performed training using a threshold IMT device with the load set at 30% of maximum inspiratory mouth pressure in addition to the general exercise training program throughout the 8 weeks. The IMT took place twice a day and each session consisted of 30 breaths. Main Outcome MeasuresPrimary outcome was cough strength, measured as the cough peak flow (CPF), at the beginning and the end of the program. ResultsData from 52 participants (26 in each group) were available for the analysis. The mean age was 82.6 years; 33% were men. The change in CPF at the end of the program was 28.7±44.4 L/min in the IMT group and −7.4±26.6 L/min in the control group. A linear regression model showed that the presence or absence of IMT was associated with changes in CPF (mean difference between groups, 36.3; 95% confidence interval, 16.7-55.9; effect size, 0.99). ConclusionsIMT may be a useful intervention to improve cough strength in frail older people.

Effects of inspiratory muscle training on NT-proBNP level, functional exercises capacity and quality of life in patients with cardiac resynchronization therapy: a pilot study

Effects of inspiratory muscle training on NT-proBNP level, functional exercises capacity and quality of life in patients with cardiac resynchronization therapy: a pilot study

Acute effects of inspiratory muscle training on microcirculation in chronic heart failure patients

Acute effects of inspiratory muscle training on microcirculation in chronic heart failure patients

Effects of different inspiratory muscle training protocols on functional exercise capacity and respiratory and peripheral muscle strength in patients with chronic kidney disease: a randomized study

BackgroundPathological changes were observed in the diaphragm due to abnormal renal function in chronic kidney disease (CKD). Inspiratory muscle training (IMT) has been suggested for patients with CKD; however, the most appropriate intensity for IMT has not been determined. Therefore, this study aimed to investigate the effects of different IMT protocols on respiratory muscle strength, quadriceps femoris muscle strength (QMS), handgrip muscle strength (HGS), functional exercise capacity, quality of life (QoL), pulmonary function, dyspnoea, fatigue, balance, and physical activity (PA) levels in patients with CKD.MethodsThis randomized, controlled, single-blind study included 47 patients and they were divided into three groups: Group 1 (n = 15, IMT with 10% maximal inspiratory pressure (MIP)), Group 2 (n = 16, IMT with 30% MIP), and Group 3(n = 16; IMT with 60% MIP). MIP, maximal expiratory pressure (MEP), 6-min walking test (6-MWT), QMS, HGS, QoL, pulmonary function, dyspnoea, fatigue, balance, and PA levels were assessed before and after eight weeks of IMT.ResultsIncreases in MIP, %MIP, 6-MWT distance, and %6-MWT were significantly higher in Groups 2 and 3 than in Group 1 after IMT (p < 0.05). MEP, %MEP, FEF25-75%, QMS, HGS, and QoL significantly increased; dyspnoea and fatigue decreased in all groups (p < 0.05). FVC, PEF, and PA improved only in Group 2, and balance improved in Groups 1 and 2 (p < 0.05).ConclusionsIMT with 30% and 60% MIP similarly improves inspiratory muscle strength and functional exercise capacity. IMT with 30% is more effective in increasing PA. IMT is a beneficial method to enhance peripheral and expiratory muscle strength, respiratory function, QoL and balance, and reduce dyspnoea and fatigue. IMT with %30 could be an option for patients with CKD who do not tolerate higher intensities.Trial registrationThis study was retrospectively registered (NCT06401135, 06/05/2024).

3D-printed magnetic-based air pressure sensor for continuous respiration monitoring and breathing rehabilitation

The rapid development of point-of-care testing has made prompt diagnosis, monitoring and treatment possible for many patients suffering from chronic respiratory diseases. Currently, the biggest challenge is further optimizing testing devices to facilitate more functionalities with higher efficiency and performance, along with specificity toward patient needs. By understanding that patients with chronic respiratory diseases may have difficulty breathing within a normal range, a respiration sensor is developed focusing on sensitivities in the lower air pressure range. In contrast to the simpler airflow data, the sensor can provide respiratory air pressure as an output using a magnetic-based pressure sensor. This unconventional but highly reliable approach, combined with the rest of the simple 3D-printed design of the sensor, offers a wide range of tunability and functionalities. Due to the detachable components of the respiration sensor, the device can be easily transformed into other respiratory uses such as an inspiratory muscle training device or modified to cater for higher-ranged deep breathing. Therefore, not only does it reach very low air pressure measurement (0.1 cmH2O) for normal, tidal breathing, but the sensor can also be manipulated to detect high levels of air pressure (up to 35 cmH2O for exhalation and 45 cmH2O for inhalation). With its excellent sensitivities (0.0456 mV/cmH2O for inhalation, -0.0940 mV/cmH2O for exhalation), impressive distinction between inhalation and exhalation, and fully reproducible and convenient design, we believe that this respiration sensor will pave the way for developing multimodal and multifunctional respiration sensors within the biomedical field.

Potential Diaphragm Muscle Weakness-related Dyspnea Persists 2 Years after COVID-19 and Could Be Improved by Inspiratory Muscle Training: Results of an Observational and an Interventional Clinical Trial.

Rationale: Diaphragm muscle weakness might underlie persistent exertional dyspnea, despite normal lung and cardiac function in individuals who were previously hospitalized for acute coronavirus disease (COVID-19) illness. Objectives: The authors sought, first, to determine the persistence and pathophysiological nature of diaphragm muscle weakness and its association with exertional dyspnea 2 years after hospitalization for COVID-19 and, second, to investigate the impact of inspiratory muscle training (IMT) on diaphragm and inspiratory muscle weakness and exertional dyspnea in individuals with long COVID. Methods: Approximately 2 years after hospitalization for COVID-19, 30 individuals (11 women, 19 men; median age, 58 years; interquartile range [IQR] = 51-63) underwent comprehensive (invasive) respiratory muscle assessment and evaluation of dyspnea. Eighteen with persistent diaphragm muscle weakness and exertional dyspnea were randomized to 6 weeks of IMT or sham training; assessments were repeated immediately after and 6 weeks after IMT completion. The primary endpoint was change in inspiratory muscle fatiguability immediately after IMT. Measurements and Main Results: At a median of 31 months (IQR = 23-32) after hospitalization, 21 of 30 individuals reported relevant persistent exertional dyspnea. Diaphragm muscle weakness on exertion and reduced diaphragm cortical activation were potentially related to exertional dyspnea. Compared with sham control, IMT improved diaphragm and inspiratory muscle function (sniff transdiaphragmatic pressure, 83 cm H2O [IQR = 75-91] vs. 100 cm H2O [IQR = 81-113], P = 0.02), inspiratory muscle fatiguability (time to task failure, 365 s [IQR = 284-701] vs. 983 s [IQR = 551-1,494], P = 0.05), diaphragm voluntary activation index (79% [IQR = 63-92] vs. 89% [IQR = 75-94], P = 0.03), and dyspnea (Borg score, 7 [IQR = 5.5-8] vs. 6 [IQR = 4-7], P = 0.03). Improvements persisted for 6 weeks after IMT completion. Conclusions: To the best of the authors' knowledge, this study is the first to identify a potential treatment for persisting exertional dyspnea in long COVID and provide a possible pathophysiological explanation for the treatment benefit. Clinical trial registered with www.clinicaltrials.gov (NCT04854863, NCT05582642).

Effects of inspiratory muscle training on thoracoabdominal volume regulation in older adults: A randomised controlled trial

ObjectivesWe investigated the effect of inspiratory muscle training (IMT) on inspiratory muscle strength, functional capacity and respiratory muscle kinematics during exercise in healthy older adults. Methods24 adults were randomised into an IMT or SHAM-IMT group. Both groups performed 30 breaths, twice daily, for 8 weeks, at intensities of ∼50 % maximal inspiratory pressure (PImax; IMT) or <15 % PImax (SHAM-IMT). Measurements of PImax, breathing discomfort during a bout of IMT, six-minute walk distance, physical activity levels, and balance were assessed pre- and post-intervention. Respiratory muscle kinematics were assessed via optoelectronic plethysmography (OEP) during constant work rate cycling. ResultsPImax was significantly improved (by 20.0±11.9 cmH2O; p=0.001) in the IMT group only. Breathing discomfort ratings during IMT significantly decreased (from 3.5±0.9–1.7±0.8). Daily sedentary time was decreased (by 28.0±39.8 min; p=0.042), and reactive balance significantly improved (by 1.2±0.8; p<0.001) in the IMT group only. OEP measures showed a significantly greater contribution of the pulmonary and abdominal rib cage compartments to total tidal volume expansion post-IMT. ConclusionsIMT significantly improves inspiratory muscle strength and breathing discomfort in this population. IMT induces greater rib cage expansion and diaphragm descent during exercise, thereby suggesting a less restrictive effect on thoracic expansion and increased diaphragmatic power generation.