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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.

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BACKGROUND: Progressive exercise intolerance is a hallmark of pulmonary hypertension (pH), severely impacting patients' independence and quality of life (QoL). Accumulating evidence over the last decade shows that combined abnormalities in peripheral reflexes and target organs contribute to disease progression and exercise intolerance. OBJECTIVE: The aim of this study was to review the literature of the last decade on the contribution of the cardiovascular, respiratory, and musculoskeletal systems to pathophysiology and exercise intolerance in pH. METHODS: A systematic literature search was conducted using specific terms in PubMed, SciELO, and the Cochrane Library databases for original pre-clinical or clinical studies published between 2013 and 2023. Studies followed randomized controlled/non-randomized controlled and pre-post designs. RESULTS: The systematic review identified 25 articles reporting functional or structural changes in the respiratory, cardiovascular, and musculoskeletal systems in pH. Moreover, altered biomarkers in these systems, lower cardiac baroreflex, and heightened peripheral chemoreflex activity seemed to contribute to functional changes associated with poor prognosis and exercise intolerance in pH. Potential therapeutic strategies acutely explored involved manipulating the baroreflex and peripheral chemoreflex, improving cardiovascular autonomic control via cardiac vagal control, and targeting specific pathways such as GPER1, GDF-15, miR-126, and the JMJD1C gene. CONCLUSION: Information published in the last 10 years advances the notion that pH pathophysiology involves functional and structural changes in the respiratory, cardiovascular, and musculoskeletal systems and their integration with peripheral reflexes. These findings suggest potential therapeutic targets, yet unexplored in clinical trials, that could assist in improving exercise tolerance and QoL in patients with pH.

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Hypoxia increases inspiratory muscle work and consequently contributes to a reduction in exercise performance. We evaluate the effects of inspiratory muscle warm-up (IMW) on a 10 km cycling time trial in normoxia (NOR) and hypoxia (HYP). Eight cyclists performed four time trial sessions, two in HYP (FiO2: 0.145) and two in NOR (FiO2: 0.209), of which one was with IMW (set at 40% of maximal inspiratory pressure-MIP) and the other was with the placebo effect (PLA: set at 15% MIP). Time trials were unchanged by IMW (NORIMW: 893.8 ± 31.5 vs. NORPLA: 925.5 ± 51.0 s; HYPIMW: 976.8 ± 34.2 vs. HYPPLA: 1008.3 ± 56.0 s; p > 0.05), while ventilation was higher in HYPIMW (107.7 ± 18.3) than HYPPLA (100.1 ± 18.9 L.min-1; p ≤ 0.05), and SpO2 was lower (HYPIMW: 73 ± 6 vs. HYPPLA: 76 ± 6%; p ≤ 0.05). A post-exercise-induced reduction in inspiratory strength was correlated with exercise elapsed time during IMW sessions (HYPIMW: r = -0.79; p ≤ 0.05; NORIMW: r = -0.70; p ≤ 0.05). IMW did not improve the 10 km time trial performance under normoxia and hypoxia.

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INTRODUCTION: Protocols for obtaíníng the maxímum threshold pressure have been applied wíth límited precision to evaluate ínspiratory muscle endurance. In thís sense, new protocols are needed to allow more relíable measurements. The purpose of the present study was to compare a new incremental ramp load protocol for the evaluation of ínspíratory muscle endurance wíth the most used protocol in healthy indíviduals. METHODS: This was a prospective cross-sectional study carried out ín a síngle center. Nínety-two healthy indíviduals (43 men [22 ± 3 years] and 49 women [22 ± 3 years]) were randomly allocated to perform: (i) íncremental ramp load protocol and (íí) íncremental step loadíng protocol. The sustained pressure threshold (or maximum threshold pressure), maximum threshold pressure/dynamic strength índex ratío, time untíl task faílure, as well as dífference between the mean heart rate of the last five mínutes of baselíne and the peak heart rate of the last 30 seconds of each protocol were measured. RESULTS: Incremental ramp load protocol wíth small íncreases in the load and starting from mínímum values of strength index was able to evaluate the inspiratory muscle endurance through the maxímum threshold pressure of healthy indívíduals. CONCLUSION: The present study suggests that the íncremental ramp load protocol is able to measure maximum threshold pressure in a more thorough way, wíth less progression and greater accuracy in the load stratification compared to the límited incremental step loading protocol and with a safe and expected cardiovascular response in healthy individuals.

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OBJECTIVE: People living with chronic kidney disease (CKD) and receiving hemodialysis (HD) have impaired respiratory muscle strength and endurance. The objective of this study was to systematically review the effects of inspiratory muscle training (IMT) on respiratory muscle strength, functional capacity, lung function, quality of life, endothelial function, and oxidative stress in people living with CKD and receiving HD. METHODS: An electronic search was conducted from inception to June 2023. Randomized controlled trials that evaluated the effects of IMT on respiratory muscle strength, functional capacity, lung function, endothelial function, quality of life, or oxidative stress in adults living with CKD and receiving HD, compared with control, placebo IMT, or conventional physical therapy, were included. RESULTS: Eight studies were included, totaling 246 people. The meta-analysis showed that IMT increased the maximum inspiratory pressure (MIP) by 22.53 cm H2O, the maximum expiratory pressure (MEP) by 19.54 cm H2O, and the distance covered in the 6-minute walk test by 77.63 m. Changes in lung function and quality of life were not observed. It was not possible to quantitatively analyze data on endothelial function and oxidative stress. CONCLUSION: IMT improves MIP, MEP, and functional capacity in people living with CKD and receiving HD. IMT did not demonstrate significant results for lung function and quality of life. Effects on endothelial function and oxidative capacity remain uncertain. IMPACT: Inspiratory muscle training improves MIP, MEP, and functional capacity in people living with CKD and receiving HD, compared with conventional physical therapy or controls or placebo intervention. Increases in functional capacity in this population are extremely important because of the relationship with the survival of these people.

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BACKGROUND: Maximal respiratory pressure is used to assess the inspiratory and expiratory muscles strength by using maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax). This study aimed to summarize and evaluate the reliability and validity of maximal respiratory pressure measurements. METHODS: This systematic review followed the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) recommendations and was reported by using the PRISMA checklist. Studies published before March 2023 were searched in PubMed and EMBASE databases. RESULTS: A total of 642 studies were identified by using the online search strategy and manual search (602 and 40, respectively). Twenty-three studies were included. The level of evidence for test-retest reliability was moderate for PImax and PEmax (intraclass correlation coefficient > 0.70 for both), inter-rater reliability was low for PImax and very low for PEmax (intraclass correlation coefficient > 0.70 for both), and the measurement error was very low for PImax and PEmax. In addition, concurrent validity presented a high level of evidence for PImax and PEmax (r > 0.80). CONCLUSIONS: Only concurrent validity of maximal respiratory pressure measured with the manometers evaluated in this review presented a high level of evidence. The quality of clinical studies by using maximal respiratory pressure would be improved if more high-quality studies on measurement properties, by following well established guidelines and the COSMIN initiative, were available.

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BACKGROUND: The non-invasive assessment of maximal respiratory pressures (MRP) reflects the strength of the respiratory muscles. OBJECTIVE: To evaluate the studies which have established normative values for MRP in healthy children and adolescents and to synthesize these values through a meta-analysis. METHODS: The searches were conducted until October 2023 in the following databases: ScienceDirect, MEDLINE, CINAHL, SciELO, and Web of Science. Articles that determined normative values and/or reference equations for maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in children and adolescents published in English, Portuguese, or Spanish regardless of the year of publication were included. Two reviewers selected titles and abstracts, in case of conflict, a third reviewer was consulted. Articles that presented sufficient data were included to conduct the meta-analysis. RESULTS: Initially, 252 studies were identified, 28 studies were included in the systematic review and 19 in the meta-analysis. The sample consisted of 5798 individuals, and the MIP and MEP values were stratified by sex and age groups of 4-11 and 12-19 years. Values from females 4-11 years were: 65.8 cmH2O for MIP and 72.8 cmH2O for MEP, and for males, 75.4 cmH2O for MIP and 84.0 cmH2O for MEP. In the 12-19 age group, values for females were 82.1 cmH2O for MIP and 90.0 cmH2O for MEP, and for males, they were 95.0 cmH2O for MIP and 105.7 cmH2O for MEP. CONCLUSIONS: This meta-analysis suggests normative values for MIP and MEP in children and adolescents based on 19 studies.

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Rationale: Hypoxemia during mechanical ventilation might be worsened by expiratory muscle activity, which reduces end-expiratory lung volume through lung collapse. A proposed mechanism of benefit of neuromuscular blockade in acute respiratory distress syndrome (ARDS) is the abolition of expiratory efforts. This may contribute to the restoration of lung volumes. The prevalence of this phenomenon, however, is unknown. Objectives: To investigate the incidence and amount of end-expiratory lung impedance (EELI) increase after the administration of neuromuscular blocking agents (NMBAs), clinical factors associated with this phenomenon, its impact on regional lung ventilation, and any association with changes in pleural pressure. Methods: We included mechanically ventilated patients with ARDS monitored with electrical impedance tomography (EIT) who received NMBAs in one of two centers. We measured changes in EELI, a surrogate for end-expiratory lung volume, before and after NMBA administration. In an additional 10 patients, we investigated the characteristic signatures of expiratory muscle activity depicted by EIT and esophageal catheters simultaneously. Clinical factors associated with EELI changes were assessed. Measurements and Main Results: We included 46 patients, half of whom showed an increase in EELI of >10% of the corresponding Vt (46.2%; IQR, 23.9-60.9%). The degree of EELI increase correlated positively with fentanyl dosage and negatively with changes in end-expiratory pleural pressures. This suggests that expiratory muscle activity might exert strong counter-effects against positive end-expiratory pressure that are possibly aggravated by fentanyl. Conclusions: Administration of NMBAs during EIT monitoring revealed activity of expiratory muscles in half of patients with ARDS. The resultant increase in EELI had a dose-response relationship with fentanyl dosage. This suggests a potential side effect of fentanyl during protective ventilation.

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ABSTRACT Introduction: Protocols for obtaining the maximum threshold pressure have been applied with limited precision to evaluate inspiratory muscle endurance. In this sense, new protocols are needed to allow more reliable measurements. The purpose of the present study was to compare a new incremental ramp load protocol for the evaluation of inspiratory muscle endurance with the most used protocol in healthy individuals. Methods: This was a prospective cross-sectional study carried out in a single center. Ninety-two healthy individuals (43 men [22 ± 3 years] and 49 women [22 ± 3 years]) were randomly allocated to perform: (i) incremental ramp load protocol and (ii) incremental step loading protocol. The sustained pressure threshold (or maximum threshold pressure), maximum threshold pressure/dynamic strength index ratio, time until task failure, as well as difference between the mean heart rate of the last five minutes of baseline and the peak heart rate of the last 30 seconds of each protocol were measured. Results: Incremental ramp load protocol with small increases in the load and starting from minimum values of strength index was able to evaluate the inspiratory muscle endurance through the maximum threshold pressure of healthy individuals. Conclusion: The present study suggests that the incremental ramp load protocol is able to measure maximum threshold pressure in a more thorough way, with less progression and greater accuracy in the load stratification compared to the limited incremental step loading protocol and with a safe and expected cardiovascular response in healthy individuals.

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BACKGROUND: Measuring maximal respiratory pressure is a widely used method of investigating the strength of inspiratory and expiratory muscles. OBJECTIVES: To compare inspiratory pressures obtained at functional residual capacity (FRC) with measures at residual volume (RV), and expiratory pressures obtained at FRC with measures at total lung capacity (TLC) in individuals with different health conditions: post-COVID-19, COPD, idiopathic pulmonary fibrosis (IPF), heart failure (CHF), and stroke; and to compare the mean differences between measurements at FRC and RV/TLC among the groups. METHODS: Inspiratory and expiratory pressures were obtained randomly at different lung volumes. Mixed factorial analysis of covariance with repeated measures was used to compare measurements at different lung volumes within and among groups. RESULTS: Seventy-five individuals were included in the final analyses (15 individuals with each health condition). Maximal inspiratory pressures at FRC were lower than RV [mean difference (95% CI): 11.3 (5.8, 16.8); 8.4 (2.3, 14.5); 11.1 (5.5, 16.7); 12.8 (7.1, 18.4); 8.0 (2.6, 13.4) for COVID-19, COPD, IPF, CHF, and stroke, respectively] and maximal expiratory pressures at FRC were lower than TLC [mean difference (95% CI): 51.9 (37.4, 55.5); 60.9 (44.2, 77.7); 62.9 (48.1, 77.8); 58.0 (43.9, 73.8); 57.2 (42.9, 71.6) for COVID-19, COPD, IPF, CHF, and stroke, respectively]. All mean differences were similar among groups. CONCLUSION: Although inspiratory and expiratory pressures at FRC were lower than measures obtained at RV/TLC for the five groups of health conditions, the mean differences between measurements at different lung volumes were similar among groups, which raises the discussion about the influence of the viscoelastic properties of the lungs on maximal respiratory pressure.

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