Inspiratory muscle training in neuromuscular patients: Assessing the benefits of a novel protocol

BACKGROUND

Neuromuscular diseases are characterized by the compromise of respiratory muscles, thoracic ventilation, muscle strength and coughing capacity. Patients have low quality of life and increased morbidity and mortality mostly due to respiratory impairment.

OBJECTIVE

To assess the benefits of adding inspiratory muscle training to neuromuscular patients' treatment and their compliance to the approach.

METHODS

We conducted a single-center prospective study with neuromuscular patients with decreased maximal inspiratory pressure. We developed an inspiratory muscle training protocol with three-month duration and once-daily training. The protocol had a progressive intensity that was individually tailored based on patients' baseline characteristics and tolerance. We used Powerbreathe Medic Classic devices to perform the training.

RESULTS

There were 21 patients who met the inclusion criteria and were enrolled in the study. Muscular dystrophy (n= 12, 57.3%) and amyotrophic lateral sclerosis (n= 4, 19%) were the most common diseases. After three months of training, patients increased their maximal inspiratory muscle pressure (p= 0.002) and peak cough flow (p= 0.011). Compliance to the protocol was 99 ± 5.5%.

CONCLUSIONS

This protocol showed significant improvements on pulmonary muscles function and might be considered as an adjunct treatment to neuromuscular treatment. However, these positive results require larger further studies to validate the clinical benefits long-term.

Effect of resistance exercises applying maximum expiration on the respiratory muscle strength of elderly women

BACKGROUND

Respiratory-muscle weakness is an important clinical problem. The respiratory system's health is a decisive factor in the physical and social life of the elderly. Changes in respiratory muscular strength and function activate the torso's adjustment ability, which affects daily activities.

OBJECTIVE

This study aimed to investigate the effects of resistance exercises combined with breathing exercises on the respiratory-muscle strength of elderly women.

METHOD

This study included 26 elderly woman, who were randomly divided into two sub-groups of 13 participants each. The experimental group performed breathing exercises and dynamic upper- and lower-extremity exercises, and the control group practiced only dynamic upper- and lower-extremity exercises. The maximum expiratory pressure (MEP) and maximum inspiratory pressure (MIP) were measured both before and at the end of the six-week study.

RESULTS

In both groups, both the post-test MIPs and MEPs were significantly higher than the pre-intervention ones (p< 0.05). For MIPs, the between-group difference was not statistically significant, either before the intervention or post-test (p> 0.05). For MEPs, the between-group difference was statistically significant at post-intervention points (p< 0.05).

CONCLUSION

The results showed that resistance exercises applying maximum expiration improved the respiratory-muscle strength of elderly women. These findings indicate that resistance exercises applying maximum expiration as described here in should be considered in patients who require breathing therapy, because the combination seems to significantly increase the strength of the respiratory muscles.

Evolution of inspiratory muscle function in children during mechanical ventilation

BACKGROUND

There is no universally accepted method to assess the pressure-generating capacity of inspiratory muscles in children on mechanical ventilation (MV), and no study describing its evolution over time in this population.

METHODS

In this prospective observational study, we have assessed the function of the inspiratory muscles in children on various modes of MV. During brief airway occlusion maneuvers, we simultaneously recorded airway pressure depression at the endotracheal tube (ΔPaw, force generation) and electrical activity of the diaphragm (EAdi, central respiratory drive) over five consecutive inspiratory efforts. The neuro-mechanical efficiency ratio (NME, ΔPaw/EAdimax) was also computed. The evolution over time of these indices in a group of children in the pediatric intensive care unit (PICU) was primarily described. As a secondary objective, we compared these values to those measured in a group of children in the operating room (OR).

RESULTS

In the PICU group, although median NMEoccl decreased over time during MV (regression coefficient - 0.016, p = 0.03), maximum ΔPawmax remained unchanged (regression coefficient 0.109, p = 0.50). Median NMEoccl at the first measurement in the PICU group (after 21 h of MV) was significantly lower than at the only measurement in the OR group (1.8 cmH2O/µV, Q1-Q3 1.3-2.4 vs. 3.7 cmH2O/µV, Q1-Q3 3.5-4.2; p = 0.015). Maximum ΔPawmax in the PICU group was, however, not significantly different from the OR group (35.1 cmH2O, Q1-Q3 21-58 vs. 31.3 cmH2O, Q1-Q3 28.5-35.5; p = 0.982).

CONCLUSIONS

The function of inspiratory muscles can be monitored at the bedside of children on MV using brief airway occlusions. Inspiratory muscle efficiency was significantly lower in critically ill children than in children undergoing elective surgery, and it decreased over time during MV in critically ill children. This suggests that both critical illness and MV may have an impact on inspiratory muscle efficiency.

Reduced inspiratory muscle strength increases pneumonia in patients with acute myocardial infarction

BACKGROUND

Inspiratory muscle strength is associated with pneumonia in patients after surgery or those with subacute stroke. However, inspiratory muscle strength in patients with acute myocardial infarction (AMI) has not been studied.

OBJECTIVE

To evaluate the predictive value of inspiratory muscle strength for pneumonia in patients with AMI.

METHODS

Patients with AMI were consecutively enrolled from March 2019 to September 2019. Measurements of maximal inspiratory pressure (MIP) were used to estimate inspiratory muscle strength and mostly were taken within 24 hr after culprit-vessel revascularization. Patients were divided into 3 groups by MIP tertile (T1: < 56.1 cm H2O, n = 88; T2: 56.1-84.9 cm H2O, n = 88; T3: > 84.9 cm H2O, n=89). The primary endpoint was in-hospital pneumonia.

RESULTS

Among 265 enrolled patients, pneumonia developed in 26 (10%). The rates of pneumonia were decreased from MIP T1 to T3 (T1: 17%, T2: 10%, T3: 2%, P = 0.004). In-hospital all-cause mortality and major adverse cardiovascular events (MACEs) did not differ between groups. Multivariate logistic regression confirmed increased MIP associated with reduced risk of pneumonia (odds ratio 0.78, 95% confidence interval 0.65-0.94, P = 0.008). Receiver operating characteristic curve analysis indicated that MIP had good performance for predicting in-hospital pneumonia, with an area under the curve of 0.72 (95% confidence interval 0.64-0.81, P < 0.001).

CONCLUSIONS

The risk of pneumonia but not in-hospital mortality and MACEs was increased in AMI patients with inspiratory muscle weakness. Future study focused on training inspiratory muscle may be helpful.

The Effect of Preexercise Expiratory Muscle Loading on Exercise Tolerance in Healthy Men

PURPOSE

Acute nonfatiguing inspiratory muscle loading transiently increases diaphragm excitability and global inspiratory muscle strength and may improve subsequent exercise performance. We investigated the effect of acute expiratory muscle loading on expiratory muscle function and exercise tolerance in healthy men.

METHODS

Ten males cycled at 90% of peak power output to the limit of tolerance (TLIM) after 1) 2 × 30 expiratory efforts against a pressure-threshold load of 40% maximal expiratory gastric pressure (PgaMAX) (EML-EX) and 2) 2 × 30 expiratory efforts against a pressure-threshold load of 10% PgaMAX (SHAM-EX). Changes in expiratory muscle function were assessed by measuring the mouth pressure (PEMAX) and PgaMAX responses to maximal expulsive efforts and magnetically evoked (1 Hz) gastric twitch pressure (Pgatw).

RESULTS

Expiratory loading at 40% of PgaMAX increased PEMAX (10% ± 5%, P = 0.001) and PgaMAX (9% ± 5%, P = 0.004). Conversely, there was no change in PEMAX (166 ± 40 vs 165 ± 35 cm H2O, P = 1.000) or PgaMAX (196 ± 38 vs 192 ± 39 cm H2O, P = 0.215) from before to after expiratory loading at 10% of PgaMAX. Exercise time was not different in EML-EX versus SHAM-EX (7.91 ± 1.96 vs 8.09 ± 1.77 min, 95% CI = -1.02 to 0.67, P = 0.651). Similarly, exercise-induced expiratory muscle fatigue was not different in EML-EX versus SHAM-EX (-28% ± 12% vs -26% ± 7% reduction in Pgatw amplitude, P = 0.280). Perceptual ratings of dyspnea and leg discomfort were not different during EML-EX versus SHAM-EX.

CONCLUSION

Acute expiratory muscle loading enhances expiratory muscle function but does not improve subsequent severe-intensity exercise tolerance in healthy men.

Comparison of respiratory muscle strength and endurance, maximal oxygen consumption, and fatigue in colorectal cancer survivors with healthy adults

PURPOSE

This study aimed to evaluate respiratory muscle strength and endurance, maximal oxygen consumption, and fatigue of colorectal cancer (CRC) survivors and compare them with healthy individuals.

METHODS

Demographic and clinical characteristics were recorded. Respiratory muscle strength (maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP)) was measured using an electronic mouth pressure device, and respiratory muscle endurance was assessed using a constant workload protocol with linear workload device. Peak oxygen consumption (VO₂peak) was measured using the cardiopulmonary exercise test (CPET) with modified Bruce protocol. Fatigue was assessed using the Brief Fatigue Inventory (BFI).

RESULTS

The patients had similar demographic characteristics (p > 0.05). MEP (cmH₂O and %predicted) were lower in the CRC group than in healthy controls (p < 0.05). MIP (cmH₂O and %predicted) and test duration did not differ between the groups (p > 0.05). VO₂peak (ml/min and %predicted) and VO₂peak/kg (%predicted) were significantly lower in the CRC group (p < 0.05). BFI score differed significantly in the CRC and control groups (p < 0.05).

CONCLUSION

Respiratory muscle strength, maximal exercise capacity, and fatigue are adversely affected in CRC survivors. Cancer treatment may cause loss of muscle strength and impair energy metabolism and oxygen transmission. These changes can result in decreased exercise capacity and respiratory muscle strength and increased fatigue. Studies examining the effects of different exercise training programs in CRC survivors are needed.

Effects of the Turbine™ on Ventilatory and Sensory Responses to Incremental Cycling

INTRODUCTION

The Turbine™ is a nasal dilator marketed to athletes to increase airflow, which may serve to reduce dyspnea and improve exercise performance, presumably via reductions in the work of breathing (WOB). However, the unpublished data supporting these claims were collected in individuals at rest that were exclusively nasal breathing. These data are not indicative of how the device influences breathing during exercise at higher ventilations when a larger proportion of breathing is through the mouth. Accordingly, the purpose of this study was to empirically test the efficacy of the Turbine™ during exercise. We hypothesized that the Turbine™ would modestly reduce the WOB at rest and very low exercise intensities but would have no effect on the WOB at moderate to high exercise intensities.

METHODS

We conducted a randomized crossover study in young, healthy individuals (7M:1F; age = 27 ± 5 yr) with normal lung function. Each participant performed two incremental cycle exercise tests to exhaustion with the Turbine™ device or under a sham control condition. For the sham control condition, participants were told they were breathing a low-density gas to reduce the WOB, but they were actually breathing room air. The WOB was determined through the integration of ensemble averaged esophageal pressure-volume loops. Standard cardiorespiratory measures were recorded using a commercially available metabolic cart. Dyspnea was assessed throughout exercise using the 0-10 Borg scale.

RESULTS

Peak V˙O2 and work rate were not different between conditions (P = 0.70 and P = 0.35, respectively). In addition, there was no interaction or main effect of condition on dyspnea, ventilation, or WOB throughout the exercise (all P > 0.05).

CONCLUSION

These findings suggest that the Turbine™ does not reduce the WOB and has no effect on dyspnea or exercise capacity.

Effects of yogic intervention on pulmonary function and respiratory muscle strength parameters: A systematic literature review and meta-analysis

The aim of this systematic review and meta-analysis is to investigate the efficacy of yogic intervention (YI) on pulmonary functions (PFs) and respiratory muscle strength parameters in healthy individuals. PubMed/Medline, Embase, Google Scholar, SPORTdiscus databases as well as manual searches carried out until March 2020 on yoga AND pulmonary function were included based on Prisma guidelines. Twenty studies were identified potentially relevant. They were systematically reviewed and summarized in tabular form, listing yogic intervention (YI) significant improved forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1); FEV1/FVC; peak expiratory flow rate (PEFR), maximum voluntary volume (MVV), respiratory muscle strength parameters like maximum inspiratory pressure (MIP), and maximum expiratory pressure (MEP or PEmax). There are encouraging results elucidated that yogic intervention improves pulmonary functions and respiratory muscle strength parameters of healthy physically fit individuals significantly.

Respiratory muscle training for cystic fibrosis

BACKGROUND

Cystic fibrosis is the most common autosomal recessive disease in white populations, and causes respiratory dysfunction in the majority of individuals. Numerous types of respiratory muscle training to improve respiratory function and health-related quality of life in people with cystic fibrosis have been reported in the literature. Hence a systematic review of the literature is needed to establish the effectiveness of respiratory muscle training (either inspiratory or expiratory muscle training) on clinical outcomes in cystic fibrosis. This is an update of a previously published review.

OBJECTIVES

To determine the effectiveness of respiratory muscle training on clinical outcomes in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials register comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Date of most recent search: 11 June 2020. A hand search of the Journal of Cystic Fibrosis and Pediatric Pulmonology was performed, along with an electronic search of online trial databases. Date of most recent search: 05 October 2020.

SELECTION CRITERIA

Randomised controlled studies comparing respiratory muscle training with a control group in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Review authors independently selected articles for inclusion, evaluated the methodological quality of the studies, and extracted data. Additional information was sought from trial authors where necessary. The quality of the evidence was assessed using the GRADE system.

MAIN RESULTS

Authors identified 20 studies, of which 10 studies with 238 participants met the review's inclusion criteria. There was wide variation in the methodological and written quality of the included studies. Four of the 10 included studies were published as abstracts only and lacked concise details, thus limiting the information available. Eight studies were parallel studies and two of a cross-over design. Respiratory muscle training interventions varied dramatically, with frequency, intensity and duration ranging from thrice weekly to twice daily, 20% to 80% of maximal effort, and 10 to 30 minutes, respectively. Participant numbers ranged from 11 to 39 participants in the included studies; five studies were in adults only, one in children only and four in a combination of children and adults. No differences between treatment and control were reported in the primary outcome of pulmonary function (forced expiratory volume in one second and forced vital capacity) or postural stability (very low-quality evidence). Although no change was reported in exercise capacity as assessed by the maximum rate of oxygen use and distance completed in a six minute walk test, a 10% improvement in exercise duration was found when working at 60% of maximal effort in one study (n = 20) (very low-quality evidence). In a further study (n = 18), when working at 80% of maximal effort, health-related quality of life improved in the mastery and emotion domains (very low-quality evidence). With regards to the review's secondary outcomes, one study (n = 11) found a change in intramural pressure, functional residual capacity and maximal inspiratory pressure following training (very low-quality evidence). Another study (n=36) reported improvements in maximal inspiratory pressure following training (P < 0.001) (very low-quality evidence). A further study (n = 22) reported that respiratory muscle endurance was longer in the training group (P < 0.01). No studies reported significant differences on any other secondary outcomes. Meta-analyses could not be performed due to a lack of consistency and insufficient detail in reported outcome measures.

AUTHORS' CONCLUSIONS

There is insufficient evidence to suggest whether this intervention is beneficial or not. Healthcare practitioners should consider the use of respiratory muscle training on a case-by-case basis. Further research of reputable methodological quality is needed to determine the effectiveness of respiratory muscle training in people with cystic fibrosis. Researchers should consider the following clinical outcomes in future studies; respiratory muscle function, pulmonary function, exercise capacity, hospital admissions, and health-related quality of life. Sensory-perceptual changes, such as respiratory effort sensation (e.g. rating of perceived breathlessness) and peripheral effort sensation (e.g. rating of perceived exertion) may also help to elucidate mechanisms underpinning the effectiveness of respiratory muscle training.

Inspiratory muscle training at sea level improves the strength of inspiratory muscles during load carriage in cold-hypoxia

Inspiratory muscle training (IMT) and functional IMT (IMT_F: exercise-specific IMT activities) has been unsuccessful in reducing respiratory muscle fatigue following load carriage. IMT_F did not include load carriage specific exercises. Fifteen participants split into two groups (training and control) walked 6 km loaded (18.2 kg) at speeds representing ∼50%V̇O_2max in cold-hypoxia. The walk was completed at baseline; post 4 weeks IMT and 4 weeks IMT_F (five exercises engaging core muscles, three involved load). The training group completed IMT and IMT_F at a higher maximal inspiratory pressure (P_imax) than controls. Improvements in P_imax were greater in the training group post-IMT (20.4%, p  = .025) and post-IMT_F (29.1%, p  = .050) compared to controls. Respiratory muscle fatigue was unchanged (p  = .643). No other physiological or subjective measures were improved by IMT or IMT_F. Both IMT and IMT_F increased the strength of respiratory muscles pre-and-post a 6 km loaded walk in cold-hypoxia. Practitioner Summary: To explore the interaction between inspiratory muscle training (IMT), load carriage and environment, this study investigated 4 weeks IMT and 4 weeks functional IMT on respiratory muscle strength and fatigue. Functional IMT improved inspiratory muscle strength pre-and-post a loaded walk in cold-hypoxia but had no more effect than IMT alone. Abbreviations: ANOVA: analysis of variance; BF: breathing frequency; CON: control group; EELV: end-expiratory lung volume; EXP: experimental group; FEV₁: forced expiratory volume in one second; FiO₂: fraction of inspired oxygen; FVC: forced vital capacity; HR: heart rate; IMT: inspiratory muscle training; IMT_F: functional inspiratory muscle training; P_emax: maximal expiratory pressure; P_imax: maximal inspiratory pressure; RMF: respiratory muscle fatigue; RPE: rate of perceived exertion; RWU: respiratory muscle warm-up; SaO₂: arterial oxygen saturation; SpO₂: peripheral oxygen saturation; V̇E: minute ventilation; V̇O₂: rate of oxygen uptake.

Effect of Passive Stretching of Respiratory Muscles on Chest Expansion and 6-Minute Walk Distance in COPD Patients

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. Hyperinflation of the lungs leads to a remodeling of the inspiratory muscles that causes postural deformities and more labored breathing. Postural changes include elevated, protracted, or abducted scapulae with medially rotated humerus, and kyphosis that leads to further tightening of respiratory muscles. As the severity of the disease progresses, use of the upper limbs for functional tasks becomes difficult due to muscle stiffness. There are various studies that suggest different rehabilitation programs for COPD patients; however, to the best of our knowledge none recommends passive stretching techniques. The aim of this study was to assess the effect of respiratory muscle passive stretching on chest expansion and 6-min walk distance (6MWD) in patients with moderate to severe COPD.

METHODS

Thirty patients were divided into two groups, experimental (n = 15) and control (n = 15). The experimental group received a hot pack followed by stretching of the respiratory muscles and relaxed passive movements of the shoulder joints. The control group received a hot pack followed by relaxed passive movements of the shoulder joints.

RESULTS

In the control group, there was no difference in chest expansion at the levels of both the axilla and the xiphisternum or in 6MWD between baseline and post treatment (p > 0.05). In the experimental group, chest expansion at the level of the axilla (p < 0.05) and 6MWD (p < 0.001) were significantly higher post treatment, while there was no difference in chest expansion at the level of the xiphisternum (p > 0.05). A comparison between control and experimental groups showed that chest expansion at the level of the axilla (p < 0.05) and 6MWD (p < 0.01) were significantly higher in the experimental group, while there was no difference in chest expansion at the level of the xiphisternum (p > 0.05).

CONCLUSIONS

Although COPD is an irreversible disease, results of this study indicate that passive stretching of respiratory muscles can clinically improve the condition of such patients, especially in terms of chest expansion and 6MWD. Given the good effects of muscle stretching and the fact that such an exercise is harmless, clinicians and physiotherapists should consider including passive stretching of respiratory muscles in the rehabilitation plan of COPD patients.

Long-Term Combined Training in Idiopathic Pulmonary Fibrosis: A Case Study

A supervised combined training program was applied to a sedentary 56-year-old man with idiopathic pulmonary fibrosis (IPF) along three years, until lung transplantation. It included: (a) aerobic continuous (CT) and interval training (IT), (b) high load resistance training (RT) and (c) inspiratory muscle training (IMT). IT and IMT were applied for two years, while CT and RT could be maintained until transplantation using supplemental oxygen. Maximal inspiratory pressure (MIP) kept above 180 cm H₂O and forced vital capacity (FVC) remained stable until lung transplantation. Peak oxygen uptake VO₂ increased during 1.5 years before its decline, staying above the poor prognosis level two years. Finally, the patient maintained his walking capacity and independence for 2 years, before the decline due to the disease. After receiving a two-lung transplant, the patient remained intubated for 12 h, left the intensive care unit after 3.5 days and was discharged after 18 days (average values: 48 h, 7–10 days and 25–35 days, respectively). These results show that systematic and supervised combined training can be safety applied in an IPF patient to maintain functionality and quality of life. In addition, we show that RT can be maintained for as long as necessary without complications.

Cardiopulmonary Rehabilitation Improves Respiratory Muscle Function and Functional Capacity in Children with Congenital Heart Disease. A Prospective Cohort Study

Critical surgical and medical advances have shifted the focus of congenital heart disease (CHD) patients from survival to achievement of a greater health-related quality of life (HRQoL). HRQoL is influenced, amongst other factors, by aerobic capacity and respiratory muscle strength, both of which are reduced in CHD patients. This study evaluates the influence of a cardiopulmonary rehabilitation program (CPRP) on respiratory muscle strength and functional capacity. Fifteen CHD patients, ages 12 to 16, with reduced aerobic capacity in cardiopulmonary exercise testing (CPET) were enrolled in a CPRP involving strength and aerobic training for three months. Measurements for comparison were obtained at the start, end, and six months after the CPRP. A significant improvement of inspiratory muscle strength was evidenced (maximum inspiratory pressure 21 cm H₂O, 23%, p < 0.01). The six-minute walking test showed a statistically and clinically significant rise in walked distance (48 m, p < 0.01) and a reduction in muscle fatigue (1.7 out of 10 points, p = 0.017). These results suggest CPRP could potentially improve respiratory muscle function and functional capacity, with lasting results, in children with congenital heart disease, but additional clinical trials must be conducted to confirm this finding.

Effectiveness of inspiratory muscle training associated with a cardiac rehabilitation program on sympathetic activity and functional capacity in patients with heart failure: a study protocol for a randomized controlled trial

BACKGROUND

Individuals affected by heart failure (HF) may present fatigue, dyspnea, respiratory muscle weakness, and sympathetic activity hyperstimulation of the myocardium, among other symptoms. Conducting cardiac rehabilitation (CR) programs can be associated with inspiratory muscle training. The aim of this study was to evaluate the efficacy of inspiratory muscular training (IMT) associated with a CR program on modulating myocardial sympathetic activity and maximal functional capacity, submaximal functional capacity, thickness, and mobility of the diaphragm muscle in patients with HF.

METHODS

We will conduct a clinical, controlled, randomized, double-blind trial that will include sedentary men and women who are 21-60 years old and who have diagnosed systolic HF and a left ventricular ejection fraction of less than 45%. Participants will be randomly assigned to one of two groups: experimental and control. The control group will follow the conventional CR protocol, and the experimental group will follow the conventional CR protocol associated with IMT 7 days a week. The two proposed exercise protocols will have a frequency of three times a week for a period of 12 weeks. The sympathetic innervation of the cardiac muscle, the maximum and submaximal functional capacity, diaphragm mobility and thickness, and the quality of life of the participants will be evaluated before and after the intervention protocol.

DISCUSSION

This clinical trial will be the first study to investigate the additional effects of IMT on CR in sympathetic hyperstimulation in the myocardium. The results of this study will contribute to developing therapeutic strategies collaborating to elucidate whether the association of IMT with CR can induce clinical benefits for patients with HF.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02600000. Registered November 9, 2015. Retrospectively registered.

Pulmonary and Respiratory Muscle Function in Response to Marathon and Ultra-Marathon Running: A Review

The physiological demands of marathon and ultra-marathon running are substantial, affecting multiple body systems. There have been several reviews on the physiological contraindications of participation; nevertheless, the respiratory implications have received relatively little attention. This paper provides an up-to-date review of the literature pertaining to acute pulmonary and respiratory muscle responses to marathon and ultra-marathon running. Pulmonary function was most commonly assessed using spirometry, with infrequent use of techniques including single-breath rebreathe and whole-body plethysmography. All studies observed statistically significant post-race reductions in one-or-more metrics of pulmonary function, with or without evidence of airway obstruction. Nevertheless, an independent analysis revealed that post-race values rarely fell below the lower-limit of normal and are unlikely, therefore, to be clinically significant. This highlights the virtue of healthy baseline parameters prior to competition and, although speculative, there may be more potent clinical manifestations in individuals with below-average baseline function, or those with pre-existing respiratory disorders (e.g., asthma). Respiratory muscle fatigue was most commonly assessed indirectly using maximal static mouth-pressure manoeuvres, and respiratory muscle endurance via maximum voluntary ventilation (MVV₁₂). Objective nerve-stimulation data from one study, and others documenting the time-course of recovery, implicate peripheral neuromuscular factors as the mechanism underpinning such fatigue. Evidence of respiratory muscle fatigue was more prevalent following marathon compared to ultra-marathon, and might be a factor of work rate, and thus exercise ventilation, which is tempered during longer races. Potential implications of respiratory muscle fatigue on health and marathon/ultra-marathon performance have been discussed, and include a diminished postural stability that may increase the risk of injury when running on challenging terrain, and possible respiratory muscle fatigue-induced effects on locomotor limb blood flow. This review provides novel insights that might influence marathon/ultra-marathon preparation strategies, as well as inform medical best-practice of personnel supporting such events.

Inspiratory muscle training in young, race-fit Thoroughbred racehorses during a period of detraining

Although inspiratory muscle training (IMT) is reported to improve inspiratory muscle strength in humans little has been reported for horses. We tested the hypothesis that IMT would maintain and/or improve inspiratory muscle strength variables measured in Thoroughbreds during detraining. Thoroughbreds from one training yard were placed into a control (Con, n = 3 males n = 7 females; median age 2.2±0.4 years) or treatment group (Tr, n = 5 males, n = 5 females; median age 2.1±0.3 years) as they entered a detraining period at the end of the racing/training season. The Tr group underwent eight weeks of IMT twice a day, five days per week using custom-made training masks with resistance valves and an incremental threshold of breath-loading protocol. An inspiratory muscle strength test to fatigue using an incremental threshold of breath-loading was performed in duplicate before (T₀) and after four (T₁) and eight weeks (T₂) of IMT/no IMT using a custom-made testing mask and a commercial testing device. Inspiratory measurements included the total number of breaths achieved during the test, average load, peak power, peak volume, peak flow, energy and the mean peak inspiratory muscle strength index (IMSi). Data were analysed using a linear mixed effects model, P≤0.05 significant. There were no differences for inspiratory measurements between groups at T₀. Compared to T₀, the total number of breaths achieved (P = 0.02), load (P = 0.003) and IMSi (P = 0.01) at T₂ had decreased for the Con group while the total number of breaths achieved (P<0.001), load (P = 0.03), volume (P = 0.004), flow (P = 0.006), energy (P = 0.01) and IMSi (P = 0.002) had increased for the Tr group. At T₂ the total number of breaths achieved (P<0.0001), load (P<0.0001), volume (P = 0.02), energy (P = 0.03) and IMSi (P<0.0001) were greater for the Tr than Con group. In conclusion, our results support that IMT can maintain and/or increase aspects of inspiratory muscle strength for horses in a detraining programme.

Acute inspiratory muscle exercise effect on glucose levels, glucose variability and autonomic control in patients with type 2 diabetes: A crossover randomized trial

Inspiratory muscle exercise (IME) can be an alternative to conventional exercise. We aimed to evaluate the effect of IME on glucose, glucose variability, and autonomic cardiovascular control in type 2 diabetes. Fourteen diabetic subjects were randomly assigned to IME with 2% maximal inspiratory pressure (PImax) or 60% PImax wearing a continuous glucose monitoring system for three days. Glucose variability [glucose variance (VAR), glucose coefficient of variation (CV%), glucose standard deviation (SD), and mean amplitude of glycemic excursions (MAGE)] were evaluated. Glucose reduction was observed in 5 min (60% of PImax 33.2% and 2% of PImax 32.0%), 60 min (60% of PImax 29.6% and 2% of PImax 31.4%) and 120 min (60% of PImax 21.4% and 2% of PImax 24.0%) after IME (vs.1 h before the exercise), with no difference between loads. This reduction in glucose levels was observed in all moments of the IME protocol. Glucose variability was reduced after 12 h and 18 h of the IME (ΔCV: P < 0.001, ΔSD: P < 0.001 and ΔVAR: P < 0.001) for both loads. No difference was found in MAGE (P = 0.594) after IME. Mean arterial pressure and heart rate rose during the exercise session with 60% of PImax. Although sufficiently strong to induce cardiovascular changes, an inspiratory muscle exercise session with 60% of PImax in subjects with type 2 diabetes has failed to induce any significant improvement in glucose, glucose variability and autonomic control, compared to the 2% Plmax exercise session.

Comparison of balance changes after inspiratory muscle or Otago exercise training

The inspiratory muscles contribute to balance via diaphragmatic contraction and by increasing intra-abdominal pressure. We have shown inspiratory muscle training (IMT) improves dynamic balance significantly with healthy community-dwellers. However, it is not known how the magnitude of balance improvements following IMT compares to that of an established balance program. This study compared the effects of 8-week of IMT for community-dwellers, to 8-week of the Otago exercise program (OEP) for care-residents, on balance and physical performance outcomes. Nineteen healthy community-dwellers (74 ± 4 years) were assigned to self-administered IMT. Eighteen, healthy care-residents (82 ± 4 years) were assigned to instructor-led OEP. The IMT involved 30 breaths twice-daily at ~50% of maximal inspiratory pressure (MIP). The OEP group undertook resistance and mobility exercises for ~60 minutes, twice-weekly. Balance and physical performance were assessed using the mini Balance Evaluation System Test (mini-BEST) and time up and go (TUG). After 8-week, both groups improved balance ability significantly (mini-BEST: IMT by 24 ± 34%; OEP by 34 ± 28%), with no between-group difference. Dynamic balance sub-tasks improved significantly more for the IMT group (P < 0.01), than the OEP group and vice versa for static balance sub-tasks (P = 0.01). The IMT group also improved MIP (by 66 ± 97%), peak inspiratory power (by 31 ± 12%) and TUG (by -11 ± 27%); whereas the OEP did not. IMT and OEP improved balance ability similarly, with IMT eliciting greater improvement in dynamic balance, whilst OEP improved static balance more than IMT. Unlike IMT, the OEP did not provide additional benefits in inspiratory muscle function and TUG performance. Our findings suggest that IMT offers a novel method of improving dynamic balance in older adults, which may be more relevant to function than static balance and potentially a useful adjunct to the OEP in frailty prevention.

Blood pressure and limb blood flow responses during hyperpnoea are not affected by menstrual cycle phase in young women

The purpose of this study was to clarify whether the menstrual cycle affects the cardiovascular and limb blood flow responses during hyperpnoea. Fifteen young female subjects participated. An incremental respiratory endurance test was performed at the early follicular (EF) and midluteal (ML) phases. Target minute ventilation was initially set at 30 % of maximal voluntary ventilation (MVV12) and was increased by 10 %MVV12 every 3 min. The test was terminated when the subjects no longer maintained the target ventilation. Mean arterial blood pressure (MBP) and mean blood flow in the brachial artery were continuously measured. There were no significant differences in the increase in MBP (EF: +13.0 ± 7.9 mmHg vs. ML: + 15.4 ± 12.9 mmHg during the test, F = 0.70, P = 0.59) and the decrease in brachial blood flow between the phases. These results suggest that menstrual cycle does not affect respiratory muscle-induced metaboreflex in young women.

Chest Movement and Respiratory Volume both Contribute to Thoracic Bioimpedance during Loaded Breathing

Bioimpedance has been widely studied as alternative to respiratory monitoring methods because of its linear relationship with respiratory volume during normal breathing. However, other body tissues and fluids contribute to the bioimpedance measurement. The objective of this study is to investigate the relevance of chest movement in thoracic bioimpedance contributions to evaluate the applicability of bioimpedance for respiratory monitoring. We measured airflow, bioimpedance at four electrode configurations and thoracic accelerometer data in 10 healthy subjects during inspiratory loading. This protocol permitted us to study the contributions during different levels of inspiratory muscle activity. We used chest movement and volume signals to characterize the bioimpedance signal using linear mixed-effect models and neural networks for each subject and level of muscle activity. The performance was evaluated using the Mean Average Percentage Errors for each respiratory cycle. The lowest errors corresponded to the combination of chest movement and volume for both linear models and neural networks. Particularly, neural networks presented lower errors (median below 4.29%). At high levels of muscle activity, the differences in model performance indicated an increased contribution of chest movement to the bioimpedance signal. Accordingly, chest movement contributed substantially to bioimpedance measurement and more notably at high muscle activity levels.

Beneficial Effects of Inspiratory Muscle Training Combined With Multicomponent Training in Elderly Active Women

Purpose: This study aims to analyze changes in Maximum Inspiratory Pressure (MIP), lung function, cardiorespiratory fitness, and blood pressure, in 10 healthy active elderly women, following 7 weeks of inspiratory muscle training (IMT) combined with a multicomponent training program (MCTP). The association among these health parameters, their changes after training (deltas), and the influence of MIP at baseline (MIP_pre) are also considered. Methods: IMT involved 30 inspirations at 50% of the MIP, twice daily, 7 days a week, while MCTP was 1 hr, twice a week. MIP, lung function (FVC, FEV₁, FEV₁/FVC, FEF_25-75%, PEF), 6MWT, and blood pressure (SBP, DBP), jointly with body composition, were assessed before and after the intervention. Results: Seven weeks were enough to improved MIP (p = .019; d = 1.397), 6MWT (p = .012; d = .832), SBP (p = .003; d = 1.035) and DBP (p = .024; d = .848). Despite the high physical fitness (VO₂ peak: M = 23.38, SD = 3.39 ml·min·Kg^-1), MIP_pre was low (M = 39.00, SD = 7.63 cmH₂O) and displayed a significant negative correlation with ΔMIP_pre-post (r = -.821; p < .004), showing that women who started the intervention with lower MIP achieved higher improvements in inspiratory muscle strength after training. Conclusions: No significant changes in spirometric parameters may signal that lung function is independent of early improvements in inspiratory muscles and cardiorespiratory fitness. Absence of correlation between physical fitness and respiratory outcomes suggests that being fit does not ensure cardiorespiratory health in active elderly women, so IMT might be beneficial and should supplement the MCTP in this population.

Functional training of the inspiratory muscles improves load carriage performance

Inspiratory Muscle Training (IMT) whilst adopting body positions that mimic exercise (functional IMT; IMT_F) improves running performance above traditional IMT methods in unloaded exercise. We investigated the effect of IMT_F during load carriage tasks. Seventeen males completed 60 min walking at 6.5 km·h^-1 followed by a 2.4 km load carriage time-trial (LC_TT) whilst wearing a 25 kg backpack. Trials were completed at baseline; post 4 weeks IMT (consisting of 30 breaths twice daily at 50% of maximum inspiratory pressure) and again following either 4 weeks IMT_F (comprising four inspiratory loaded core exercises) or maintenance IMT (IMT_CON). Baseline LC_TT was 15.93 ± 2.30 min and was reduced to 14.73 ± 2.40 min (mean reduction 1.19 ± 0.83 min, p < 0.01) after IMT. Following phase two, LC_TT increased in IMT_F only (13.59 ± 2.33 min, p < 0.05) and was unchanged in post-IMT_CON. Performance was increased following IMT_F, providing an additional ergogenic effect beyond IMT alone. Practitioner Summary: We confirmed the ergogenic benefit of Inspiratory Muscle Training (IMT) upon load carriage performance. Furthermore, we demonstrate that functional IMT methods provide a greater performance benefit during exercise with thoracic loads. Abbreviations: [Lac^-]_B: blood lactate; FEV₁: forced expiratory volume in one second; FEV₁/FVC: forced expiratory volume in one second/forced vital capacity ratio; FVC: forced vital capacity; HR: heart rate; IMT: inspiratory muscle training; IMT_CON: inspiratory muscle training maintenance; IMT_F: functional inspiratory muscle training; LC: load carriage; LC_TT: load carriage time trial; P_di: transdiaphragmatic pressure; PEF: peak expiratory flow; P_Emax: maximum expiratory mouth pressure; P_Imax: maximum inspiratory mouth pressure; RPE: rating of perceived exertion; RPE_breating: rating of perceived exertion for the breathing; RPE_leg: rating of perceived exertion for the legs; SEPT: sport-specific endurance plank test; V̇ O₂: oxygen consumption; V̇ O_2peak: peak oxygen consumption.

Respiratory muscle activation and action during voluntary cough in healthy humans

Cough is a defensive airway reflex consisting of a modified respiratory act which involves the sequential activation of several laryngeal and respiratory muscles. The contraction of the latter results in thoraco-abdominal volume variations in order to provide enough amount of air available, the operating volume (OV), to be expelled. Because both posture and OV could influence muscular activation and thoraco-abdominal displacements during voluntary cough, we aimed to verify if and how they play a role during inspiratory (ICP) and expiratory (ECP) cough phases, in terms of flow, volumes and surface electromyography activity (sEMG). In 10 healthy subjects, we measured sEMG of 7 muscles (scalene, sternocleidomastoid, parasternal, intercostal, diaphragm (assessed at the 8^th intercostal space), external abdominal oblique and rectus abdominis) in supine and seated position during cough maneuvers performed at 4 different OV measured by opto-electronic plethismography: total lung capacity (TLC), functional residual capacity and two intermediate volumes. The amplitude of sEMG signals tended to be maximal at TLC (p < 0.005) during ICP in the neck and parasternal muscles and during ECP in abdominal muscles. Postures slightly affected only sEMG of the thoracic muscles. sEMG data were similar (p > 0.05) in the other OV, but cough peak flow increased with OV. Thoraco-abdominal volume variations during cough were unaffected by posture and OV as well, being predominantly thoracic (supine: 60 and 64%; seated: 68 and 69%, respectively during ICP and ECP). Our results suggest that voluntary cough OV or posture do not have an important effect on voluntary cough that seems more likely to be resulting from a motor mechanism that activates a synergetic antagonistic contraction of inspiratory and expiratory muscles leading to a specific thoraco-abdominal pattern, in which the rib cage is the predominant.

Effects of Specific Core Re-Warm-Ups on Core Function, Leg Perfusion and Second-Half Team Sport-Specific Sprint Performance: A Randomized Crossover Study

This study examined the effects of a specific core exercise program, as a re-warm-up regime during the half-time period, on inspiratory (IM) and core (CM) muscle functions, leg perfusion and the team sport-specific sprint performance in the initial stage of the second half of a simulated exercise task. Nine team-sports players performed a simulated team-sport intermittent exercise protocol (IEP) in two phases, on a non-motorized treadmill, interspersed by a 15-min half-time break. During the half-time period subsequent to the 25-min Phase-1 IEP, the players either rested passively or performed 4-min CM exercise concomitant with inspiratory loaded breathing following 11-min passive recovery. The changes in IM and CM functions, leg perfusion and repeated-sprint ability mediated by the two recovery modes were compared. Following Phase-1 IEP, there was a significant decline in IM and CM functions respectively, revealed by the decreases in maximal inspiratory pressure (PImax: -8.1%) and performance of a sport-specific endurance plank test (SEPT: -29.7%, p < 0.05). With the 15-min passive recovery, the decline in IM and CM functions from pre-exercise levels were not restored satisfactorily (PImax: -6.4%, SEPT: -19.0%, p < 0.05). Moreover, repeated-sprint ability during the Phase-2 IEP tended to decrease (peak velocity: -2.3%, mean velocity: -2.1%) from the levels recorded in Phase-1. In contrast, following the re-warm-up exercises during half-time, the restoration of IM and CM function was accelerated (PImax: -0.9%, SEPT: -3.3%, p <0 .05). This was associated with enhanced repeated-sprint ability (peak velocity: +3.0%, mean velocity: +2.0%, p < 0.05) in Phase-2 IEP. Nevertheless, the changes in the anterior thigh muscle perfusion assessed by near-infrared spectroscopy following the re-warm-up exercises was not different from that of passive recovery (p > 0.05). The findings suggest that a brief inspiratory-loaded CM exercise regime appears to be an effective re-warm-up strategy that optimizes second-half repeated-sprint performance and core function of players in team sports.

Effectiveness of the muscle energy technique on respiratory muscle strength and endurance in patients with fibromyalgia

BACKGROUND

Fibromyalgia is characterized by a chronic and common musculoskeletal system pain that affects cervical mobility and inspiration. This may cause changes in thoracic mechanics.

OBJECTIVE

To investigate the effectiveness of the muscle energy technique applied to cervical accessory respiratory muscles on respiratory muscle strength and endurance in patients with fibromyalgia.

METHODS

The participants were 37 women diagnosed with fibromyalgia. They were assessed for their respiratory muscle strength, respiratory muscle endurance, pain and fatigue severity, flexibility and disability. The muscle energy technique was applied to the scalene, upper trapezius, and sternocleidomastoid muscles after a superficial heat application. The treatment was continued for 3 weeks with 3 sessions per week.

RESULTS

After the treatment, expiratory muscle strength and respiratory muscle endurance increased significantly. Severity of pain and fatigue and disability were reduced, cervical flexibility increased significantly (p< 0.05). The effect size was r⩾ 0.4 for all the variables.

CONCLUSION

The muscle energy technique applied to cervical accessory respiratory muscles in patients with fibromyalgia who had complaints in the neck and back region positively increased respiratory muscle strength and endurance, cervical flexibility, and decrease pain intensity, fatigue and disability. It is recommended that subsequent randomized studies are carried out with a placebo control group.