Effects of inspiratory muscle training on respiratory muscle electromyography and dyspnea during exercise in healthy men

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

OBJECTIVES

We investigated the effect of inspiratory muscle training (IMT) on inspiratory muscle strength, functional capacity and respiratory muscle kinematics during exercise in healthy older adults.

METHODS

24 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.

RESULTS

PImax 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.

CONCLUSIONS

IMT 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.

Correlation of cervical-inspiratory-muscle electromyography and oxygen uptake during treadmill walking

For measurements of exercise intensity, an individual's oxygen uptake (V̇O2) is measured with an exhaled gas analyzer that involves a mask, but exercise coaching would benefit if an individual's V̇O2 could be estimated with more easily obtained predictors. We investigated the predictability of V̇O2 by electromyography (EMG) of the neck inspiratory muscles. We analyzed the EMG results of the sternocleidomastoid (EMGst) and scalene (EMGsc) muscles of 14 healthy adults who performed a treadmill exercise load test. Their V̇O2, inspiratory flow rate, and heart rate were simultaneously recorded during the exercise. The exercise load test was performed twice at a ≥2-day interval. The first visit was an incremental exercise test, and the second was a repeated two-load exercise test at levels below and above the participant's ventilatory threshold (VT) as determined in the first test. We observed that the integrated EMG values for each exercise load showed partially significant positive correlations with the EMGst and EMGsc. However, the cervical inspiratory muscle EMGs did not show as high a correlation as the minute ventilation. These results indicate that (i) EMG of the cervical inspiratory muscles could be used to estimate V̇O2, but (ii) these EMG parameters alone should be considered insufficient for estimating V̇O2.

Effects of High-Intensity Inspiratory Muscle Warm-Up on High-Intensity Exercise Performance and Muscle Oxygenation

PURPOSE

An inspiratory muscle warm-up (IMW) improves inspiratory muscle function, but the effects of high-intensity exercise are inconsistent. We aimed to determine the effects of high-intensity IMW on high-intensity exercise performance and muscle oxygenation.

METHODS

Ten healthy men (maximal oxygen uptake [V˙O2max] 52.2 [5.0] mL·kg-1·min-1) performed constant-load exercise to exhaustion on a cycle ergometer at V˙O2max under 2 IMW conditions: a placebo condition (PLA) and a high-intensity IMW condition (HIGH). The inspiratory loads were set at 15% and 80% of maximal inspiratory pressure, respectively. Maximal inspiratory pressure was measured before and after IMW. Oxyhemoglobin was measured in the vastus lateralis by near-infrared spectroscopy during exercise. Rating of perceived exertion (RPE) for a leg was measured after 1 and 2 minutes of exercise.

RESULTS

Exercise tolerance was significantly higher under HIGH than PLA (228 [49] s vs 218 [49] s, P = .003). Maximal inspiratory pressure was significantly increased by IMW under HIGH (from 125 [20] to 136 [25] cm H2O, P = .031). Oxyhemoglobin was significantly higher under HIGH than PLA at 80% of the total duration of exercise (P = .048). RPE for the leg was significantly lower under HIGH than PLA after 2 minutes of exercise (P = .019).

CONCLUSIONS

Given that oxyhemoglobin is an index of local oxygen supply, the results of this study suggest that high-intensity IMW increases the oxygen supply to active limbs. It may also reflect a reduction in RPE in the leg. In addition, high-intensity IMW may improve exercise performance.

Effects of Different Inspiratory Muscle Training Protocols on Exercise Capacity, Respiratory Muscle Strength, and Health-Related Quality of Life in Patients with Hypertension

Aim

This study aimed to explore how varying inspiratory muscle training workloads affect exercise capacity, health-related quality of life (HrQoL), depression, peripheral and respiratory muscle strength, pulmonary function, dyspnea, fatigue, and physical activity levels in hypertension (HT) patients.

Methods

A randomized, controlled three-arm study. Forty-five patients (58.37 ± 8.53 y, 7F/38M) with HT received IMT (7 days/8 weeks) by POWERbreathe® Classic LR device and were randomized to control group (CG, 10% maximal inspiratory pressure (MIP), n: 15), low-load group (LLG, 30% MIP), and high-load group (HLG, %50 MIP). Exercise capacity, HrQoL, depression, peripheral and respiratory muscle strength, pulmonary function, fatigue, physical activity level, dyspnea, and sleep quality were evaluated before and after the training.

Results

Exercise capacity, physical functioning, peripheral muscle strength, and resting dyspnea were statistically significantly improved in HLG and LLG after the training compared to CG (p < 0.05). Similar improvements in perception of depression, fatigue, and sleep quality were seen within and between the groups (p > 0.05). Statistically significant differences were found within all the groups in terms of MIP and PEF values of respiratory functions (p < 0.05). The superior improvement in the physical activity level was found in the HLG (p < 0.05). Discussion. High-load IMT was particularly effective in increasing physical activity level, peripheral muscle strength, exercise capacity, and improved HrQoL. Low-load IMT was effective in reducing dyspnea and improving respiratory function. Device-guided breathing exercises decreased blood pressure, improved sleep quality, and strengthened respiratory muscles. IMT, an efficient method, is suggested for inclusion in rehabilitation programs due to its capacity to increase physical activity, exercise capacity, and peripheral muscle strength, enhance HrQoL and respiratory function, and alleviate dyspnea. Also, the efficacy of IMT should be investigated with different training protocols such as endurance IMT or functional IMT in HT patients.

Determining the Optimal Position of Surface Electrodes for Diaphragm Electromyography: A Cross-Sectional Study

BACKGROUND

Placing electrodes on different aspects of the chest determines the motor firing from the diaphragm. The electrode placement close to the extent of the muscle gave promising readings as compared to the ones that were placed away. The position with the maximum amplitude and least duration was chosen. Positions of the electrodes were decided as per the extent of the muscle. The aim is to determine the appropriate position of surface electrodes for surface diaphragm electromyography (EMG).

MATERIAL AND METHODOLOGY

Thirty healthy individuals of age ranging from 21 to 45 years were included in the study. Participants were made to lie down in a supine position and different positions like G1 (recording electrode) 5 cm superior to the tip of the xiphoid process and G2 (reference) 16 cm along the costal margin from G1, G1 over the xiphoid tip and G2 at the seventh intercostal space at the costochondral junction and G1 over the xiphoid tip and G2 at the eight intercostal space at the costochondral junction were used for assessing maximum amplitudes and durations were observed by using a Octopus New Wave EMG machine (Octopus Medical Technologies, Vadodara, IND). After observing all the positions, an optimum position for maximum amplitude and least duration was analyzed.

RESULTS

As per the study, out of the four positions, the electrode placements on the tip of the xiphoid process and 16 cm away diagonally on the sixth intercostal space showed maximum amplitude and the least duration with maximum mean amplitude and less mean duration of 232.35 and 7.316. On the seventh intercostal space it was 199.15 and 7.887 and on the eighth intercostal space was 176.055 and 8.639. The tip of the xiphoid process and 16 cm away diagonally on the sixth intercostal space is chosen as the appropriate position for electrode placement for EMG of the diaphragm.

CONCLUSION

We conclude that the best electrode position was when the electrodes were placed 5 cm superior to the xiphoid process, i.e., G1, and 16 cm away from the recording electrode on the costochondral junction, i.e., G2, at the sixth intercostal space. Ground electrode placement is the nearest bony prominence, i.e., xiphisternum.

Analysis and applications of respiratory surface EMG: report of a round table meeting

Surface electromyography (sEMG) can be used to measure the electrical activity of the respiratory muscles. The possible applications of sEMG span from patients suffering from acute respiratory failure to patients receiving chronic home mechanical ventilation, to evaluate muscle function, titrate ventilatory support and guide treatment. However, sEMG is mainly used as a monitoring tool for research and its use in clinical practice is still limited-in part due to a lack of standardization and transparent reporting. During this round table meeting, recommendations on data acquisition, processing, interpretation, and potential clinical applications of respiratory sEMG were discussed. This paper informs the clinical researcher interested in respiratory muscle monitoring about the current state of the art on sEMG, knowledge gaps and potential future applications for patients with respiratory failure.

The results of inspiratory muscle training on cardiac, respiratory, musculoskeletal, and psychological status in patients with stable angina: a randomized controlled trial

PURPOSE

To determine the effect of inspiratory muscle training (IMT) on respiratory and peripheral muscle strength, functional exercise capacity, health-related quality of life (HRQoL), fatigue, depression, and cardiac functions in patients with stable angina.

METHODS

A randomized, controlled, single-blinded study. Twenty patients (59.95 ± 7.35 y, LVEF = 58.77 ± 7.49) with stable angina received IMT at the lowest load (10 cmH2O), and 20 patients (55.85 ± 7.60 y, LVEF = 62.26 ± 7.75) received training at 30% of maximal inspiratory pressure (MIP) seven days/8 weeks. Respiratory muscle strength (MIP; maximal expiratory pressure, MEP), peripheral muscle strength, pulmonary functions, functional exercise capacity (6-min walking test; exercise test), fatigue, HRQoL, depression, and cardiac functions were evaluated before and after.

RESULTS

A statistical difference was found between groups in terms of respiratory and peripheral muscle strength, pulmonary functions, functional exercise capacity (p < 0.05). The results of fatigue, depression, HRQoL, and cardiac functions were similar between the groups (p > 0.05).

CONCLUSIONS

This study is the first to demonstrate the positive effects of IMT in patients with stable angina. IMT is a safe and effective method and is recommended to be added to cardiopulmonary rehabilitation programs and guidelines, as it results in increased peripheral muscle strength and functional exercise capacity in stable angina patients.Implications for rehabilitationInspiratory muscle training (IMT) is a safe and effective method for coronary artery disease (CAD) patients with stable angina.IMT improved respiratory and peripheral muscle strength, functional exercise capacity, pulmonary functions, and health-related quality of life in CAD patients with stable angina.Perception of depression and fatigue were decreased with IMT in CAD patients with stable angina.

The therapeutic role of inspiratory muscle training in the management of asthma: a narrative review

Asthma is a disorder of the airways characterized by chronic airway inflammation, hyperresponsiveness, and variable recurring airway obstruction. Treatment options for asthma include pharmacological strategies, whereas nonpharmacological strategies are limited. Established pharmacological approaches to treating asthma may cause unwanted side effects and do not always afford adequate protection against asthma, possibly because of an individual's variable response to medications. A potential nonpharmacological intervention that is most available and cost effective is inspiratory muscle training (IMT), which is a technique targeted at increasing the strength and endurance of the diaphragm and accessory muscles of inspiration. Studies examining the impact of IMT on asthma have reported increases in inspiratory muscle strength and a reduction in the perception of dyspnea and medication use. However, because of the limited number of studies and discordant methods between studies more evidence is required to elucidate in individuals with asthma the efficacy of IMT on inspiratory muscle endurance, exercise capacity, asthma control, symptoms, and quality of life as well as in adolescents with differing severities of asthma. Large randomized controlled trials would be a significant step forward in clarifying the effectiveness of IMT in individuals with asthma. Although IMT may have favorable effects on inspiratory muscle strength, dyspnea, and medication use, the current evidence that IMT is an effective treatment for asthma is inconclusive.

Effects of Sprint Interval and Endurance Respiratory Muscle Training on Postcycling Inspiratory and Quadriceps Fatigue

PURPOSE

We investigated whether a 4-wk period of respiratory muscle endurance training (RMET) or respiratory muscle sprint interval training (RMSIT) would lead to an attenuation of inspiratory muscle and quadriceps fatigue after a bout of high-intensity cycling compared with a placebo intervention (PLAT), as predicted by the respiratory metaboreflex model.

METHODS

Thirty-three active, young healthy adults performed RMET, RMSIT, or PLAT. Changes in inspiratory muscle and quadriceps twitches in response to a cycling test at 90% of peak work capacity were assessed before and after training. EMG activity and deoxyhemoglobin (HHb, via near-infrared spectroscopy) of the quadriceps and inspiratory muscles were also monitored during the cycling test, along with cardiorespiratory and perceptual variables.

RESULTS

At pretraining, cycling reduced the twitch force of the inspiratory muscles (86% ± 11% baseline) and quadriceps (66% ± 16% baseline). Training did not attenuate the drop in twitch force of the inspiratory muscles (PLAT, -3.5 ± 4.9 percent-points [p.p.]; RMET, 2.7 ± 11.3 p.p.; RMSIT, 4.1 ± 8.5 p.p.; group-training interaction, P = 0.394) or quadriceps (PLAT, 3.8 ± 18.6 p.p.; RMET, -2.6 ± 14.0 p.p.; RMSIT, 5.2 ± 9.8 p.p.; group-training interaction P = 0.432). EMG activity and HHb levels during cycling did not change after training for either group. Only RMSIT showed a within-group decrease in the perception of respiratory exertion with training.

CONCLUSIONS

Four weeks of RMET or RMSIT did not attenuate the development of exercise-induced inspiratory or quadriceps fatigue. The ergogenic effects of respiratory muscle training during whole-body exercise might be related to an attenuation of perceptual responses.

Early Internal Fixation of Concomitant Clavicle Fractures in Severe Thoracic Trauma Prevents Posttraumatic Pneumonia

BACKGROUND

Severe thoracic trauma can lead to pulmonary restriction, loss of lung volume, and difficulty with ventilation. In recent years, there has been increasing evidence of better clinical outcomes following surgical stabilization of clavicle fractures in the setting of this combination of injuries. The aim of this study was to evaluate surgical versus non-surgical treatment of clavicle fractures in severe thoracic trauma in terms of clinical and radiological outcomes in order to make a generalized treatment recommendation based on the results of a large patient cohort.

PATIENTS AND METHODS

This retrospective study included 181 patients (42 women, 139 men) from a European level I trauma centre with a median of 49.3 years in between 2005 and 2021. In 116 cases, the clavicle fracture was stabilized with locking plate or hook plate fixation (group 1), and in 65 cases, it was treated non-surgically (group 2). Long-term functional outcomes at least one year postoperatively using the disabilities of the arm, shoulder and hand (DASH) questionnaire and the Nottingham Clavicle Score (NCS) as well as radiological outcomes were collected in addition to parameters such as hospital days, intensive care days, and complication rates.

RESULTS

The Injury Severity Score (ISS) was 17.8 ± 9.8 in group 1 and 19.9 ± 14.4 in group 2 (mean ± SEM; p = 0.93), the time in hospital was 21.5 ± 27.2 days in group 1 versus 16 ± 29.3 days in group 2 (p = 0.04). Forty-seven patients in group 1 and eleven patients in the group 2 were treated in the ICU. Regarding the duration of ventilation (group 1: 9.1 ± 8.9 days, group 2: 8.1 ± 7.7 days; p = 0.64), the functional outcome (DASH group 1: 11 ± 18 points, group 2: 13.7 ± 18. 4 points, p = 0.51; NCS group 1: 17.9 ± 8.1 points, group 2: 19.4 ± 10.3 points, p = 0.79) and the radiological results, no significant differences were found between the treatment groups. With an overall similar complication rate, pneumonia was found in 2% of patients in group 1 and in 14% of patients in group 2 (p = 0.001).

DISCUSSION

This study could demonstrate that surgical locking plate fixation of clavicle fractures in combination with CWI significantly reducing the development of posttraumatic pneumonia in a large patient collection and, therefore, can be recommended as standard therapeutic approach for severe thoracic trauma.

The effect of inspiratory muscle training and detraining on the respiratory metaboreflex

NEW FINDINGS

What is the central question of this study? Is the attenuation of the respiratory muscle metaboreflex preserved after detraining? What is the main finding and its importance? Inspiratory muscle training increased respiratory muscle strength and attenuated the respiratory muscle metaboreflex as evident by lower heart rate and blood pressure. After 5 weeks of no inspiratory muscle training (detraining), respiratory muscle strength was still elevated and the metaboreflex was still attenuated. The benefits of inspiratory muscle training persist after cessation of training, and attenuation of the respiratory metaboreflex follows changes in respiratory muscle strength.

ABSTRACT

Respiratory muscle training (RMT) improves respiratory muscle (RM) strength and attenuates the RM metaboreflex. However, the time course of muscle function loss after the absence of training or 'detraining' is less known and some evidence suggest the respiratory muscles atrophy faster than other muscles. We sought to determine the RM metaboreflex in response to 5 weeks of RMT and 5 weeks of detraining. An experimental group (2F, 6M; 26 ± 4years) completed 5 weeks of RMT and tibialis anterior (TA) training (each 5 days/week at 50% of maximal inspiratory pressure (MIP) and 50% maximal isometric force, respectively) followed by 5 weeks of no training (detraining) while a control group (1F, 7M; 24 ± 1years) underwent no intervention. Prior to training (PRE), post-training (POST) and post-detraining (DETR), all participants underwent a loaded breathing task (LBT) to failure (60% MIP) while heart rate and mean arterial blood pressure (MAP) were measured. Five weeks of training increased RM (18 ± 9%, P < 0.001) and TA (+34 ± 19%, P < 0.001) strength and both remained elevated after 5 weeks of detraining (MIP-POST vs. MIP-DETR: 154 ± 31 vs. 153 ± 28 cmH2O, respectively, P = 0.853; TA-POST vs. TA-DETR: 86 ± 19 vs. 85 ± 16 N, respectively, P = 0.982). However, the rise in MAP during LBT was attenuated POST (-11 ± 17%, P = 0.003) and DETR (-9 ± 9%, P = 0.007) during the iso-time LBT. The control group had no change in MIP (P = 0.33), TA strength (P = 0.385), or iso-time MAP (P = 0.867) during LBT across all time points. In conclusion, RM and TA have similar temporal strength gains and the attenuation of the respiratory muscle metaboreflex remains after 5 weeks of detraining.

Does inspiratory muscle training provide additional benefits during pulmonary rehabilitation in people with interstitial lung disease? A randomized control trial

BACKGROUND

Interstitial lung disease (ILD) encompasses a diverse group of chronic lung conditions which is often characterized by inspiratory muscle weakness (IMW). Despite the potential importance of inspiratory muscle dysfunction in ILD, the effect of inspiratory muscle training (IMT) added to pulmonary rehabilitation (PR) in ILD largely remains unknown.

OBJECTIVE

The primary objective of the present study was to evaluate the benefits of IMT added to PR on inspiratory muscle strength and secondary objectives were to assess its effects on functional capacity, health-related quality of life (HRQoL), pulmonary function test (PFT) and dyspnea in ILD along with IMW.

METHODS

Fifty-one participants were randomly allocated into two groups; PR + IMT (n = 26) or PR alone (n = 25). The primary outcome [maximal inspiratory pressure (PI_max)] and secondary outcomes [6-min walk distance (6MWD), St. George's Respiratory Questionnaire (SGRQ), PFT and modified Medical Research Council dyspnea scale (mMRC)] were evaluated before and after the 8-weeks intervention. Independent t-test or Mann Whitney-U test was applied for between-group comparisons while for within-group comparison Wilcoxon's Sign Rank test or paired t test was performed.

RESULTS

At the end of 8 weeks exercise intervention inspiratory muscle strength (PI_max + 11.10 cm H₂O, p< .001), functional capacity (6MWD, + 47.90 m, p= .001), HRQoL (SGRQ-total - 4 points, p= .038) and dyspnea (mMRC dyspnea scale, -1.27, p< .001) improved significantly in PR+IMT group alone.

CONCLUSION

Inclusion of IMT to PR may have superior benefits as compared to PR alone in ILD accompanied with IMW.

Effects of Face Masks on the Multiple Dimensions and Neurophysiological Mechanisms of Exertional Dyspnea

INTRODUCTION

During the coronavirus disease 2019 pandemic, public health officials widely adopted the use of face masks (FM) to minimize infections. Despite consistent evidence that FMs increase dyspnea, no studies have examined the multidimensional components of dyspnea or their underlying physiological mechanisms.

METHODS

In a randomized crossover design, 16 healthy individuals ( n = 9 women, 25 ± 3 yr) completed incremental cycling tests over three visits, where visits 2 and 3 were randomized to either surgical FM or no mask control. Dyspnea intensity and unpleasantness were assessed throughout exercise (0-10 Borg scale), and the Multidimensional Dyspnea Profile was administered immediately after exercise. Crural diaphragmatic EMG and esophageal pressure were measured using a catheter to estimate neural respiratory drive and respiratory muscle effort, respectively.

RESULTS

Dyspnea unpleasantness was significantly greater with the FM at the highest equivalent submaximal work rate achieved by a given participant in both conditions (iso-work; 5.9 ± 1.7 vs 3.9 ± 2.9 Borg 0-10 units, P = 0.007) and at peak exercise (7.8 ± 2.1 vs 5.9 ± 3.4 Borg 0-10 units, P = 0.01) with no differences in dyspnea intensity ratings throughout exercise compared with control. There were significant increases in the sensory quality of "smothering/air hunger" ( P = 0.01) and the emotional response of "anxiousness" ( P = 0.04) in the FM condition. There were significant increases in diaphragmatic EMG and esophageal pressure at select submaximal work rates, but no differences in heart rate, pulse oximetry-derived arterial oxygen saturation, or breathing frequency throughout exercise with FMs compared with control. FMs significantly reduced peak work rate and exercise duration (both P = 0.02).

CONCLUSIONS

FMs negatively impact the affective domain of dyspnea and increase neural respiratory drive and respiratory muscle effort during exercise, although the impact on other cardiorespiratory responses are minimal.

The Effects of Respiratory Muscle Training on Resting-State Brain Activity and Thoracic Mobility in Healthy Subjects: A Randomized Controlled Trial

BACKGROUND

Although inspiratory muscle training (IMT) is an effective intervention for improving breath perception, brain mechanisms have not been studied yet.

PURPOSE

To examine the effects of IMT on insula and default mode network (DMN) using resting-state functional MRI (RS-fMRI).

STUDY TYPE

Prospective.

POPULATION

A total of 26 healthy participants were randomly assigned to two groups as IMT group (n = 14) and sham IMT groups (n = 12).

FIELD STRENGTH/SEQUENCE

A 3-T, three-dimensional T2* gradient-echo echo planar imaging sequence for RS-fMRI was obtained.

ASSESSMENT

The intervention group received IMT at 60% and sham group received at 15% of maximal inspiratory pressure (MIP) for 8 weeks. Pulmonary and respiratory muscle function, and breathing patterns were measured. Groups underwent RS-fMRI before and after the treatment.

STATISTICAL TESTS

Statistical tests were two-tailed P < 0.05 was considered statistically significant. Student's t test was used to compare the groups. One-sample t-test for each group was used to reveal pattern of functional connectivity. A statistical threshold of P < 0.001 uncorrected value was set at voxel level. We used False discovery rate (FDR)-corrected P < 0.05 cluster level.

RESULTS

The IMT group showed more prominent alterations in insula and DMN connectivity than sham group. The MIP was significantly different after IMT. Respiratory rate (P = 0.344), inspiratory time (P = 0.222), expiratory time (P = 1.000), and inspiratory time/total breath time (P = 0.572) of respiratory patterns showed no significant change after IMT. All DMN components showed decreased, while insula showed increased activation significantly.

DATA CONCLUSION

Differences in brain activity and connectivity may reflect improved ventilatory perception with IMT with a possible role in regulating breathing pattern by processing interoceptive signals.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 4.

Effectiveness of Respiratory Muscles Training by Voluntary Isocapnic Hyperpnea Versus Inspiratory Threshold Loading on Intercostales and Vastus Lateralis Muscles Deoxygenation Induced by Exercise in Physically Active Adults

Respiratory muscle training (RMT) improves physical performance, although it is still debated whether this effect depends on the type of training. The purpose of this study was to compare the effects of two different types of RMT, i.e., voluntary isocapnic hyperpnea (VIH) and inspiratory threshold loading (ITL), on the deoxygenation of intercostal (ΔSmO₂-m. intercostales) and vastus lateralis (ΔSmO₂-m. vastus lateralis) muscles during exercise. Twenty-four participants performed eight weeks of RMT by: (i) VIH (3 days·week^-1 for 12 min at 60% maximal voluntary ventilation) or (ii) ITL (5 sets·week^-1 of 30 breaths·minute^-1 at 60% maximal inspiratory pressure). Cardiopulmonary exercise testing (CPET) included ΔSmO₂ (the change from baseline to end of test) of intercostal and vastus lateralis muscles. After RMT, both groups showed decreased ΔSmO₂-m. intercostales (VIH = 12.8 ± 14.6%, p = 0.04 (effect size, ES = 0.59), and ITL = 8.4 ± 9.8%, p = 0.04 (ES = 0.48)), without a coincident change of ∆SmO_2-m. vastus lateralis. ITL training induced higher V˙O_2-peak absolute values than VIH (mean Δ post-pre, ITL = 229 ± 254 mL·min^-1 [95% CI 67-391] vs. VIH, 39 ± 153 mL·min^-1 [95% CI -58-136.0], p = 0.01). In conclusion, both RMT improved the balance between supply and oxygen consumption levels of m. intercostales during CPET, with ITL also inducing an increase of aerobic capacity.

Effect of a home-based inspiratory muscle training programme on functional capacity in postdischarged patients with long COVID: the InsCOVID trial

BACKGROUND

Fatigue and exercise intolerance are the most common symptoms in patients with long COVID.

AIMS

This study aimed to evaluate whether a home-based inspiratory muscle training (IMT) programme improves maximal functional capacity in patients' long COVID after a previous admission due to SARS-CoV-2 pneumonia.

METHODS

This study was a single-centre, blinded assessor, randomised controlled trial. Twenty-six patients with long COVID and a previous admission due to SARS-CoV-2 pneumonia were randomly assigned to receive either a 12-week IMT or usual care alone (NCT05279430). The physiotherapist and participants were not blinded. Patients allocated to the IMT arm were instructed to train at home twice daily using a threshold inspiratory muscle trainer and to maintain diaphragmatic breathing during the training session. The usual care arm received no intervention.The primary endpoint was the change in peak oxygen consumption (peakVO2). Secondary endpoints were changes in quality of life (QoL), ventilatory efficiency and chronotropic response during exercise (evaluated by chronotropic index-CI_x- formula). We used linear mixed regression analysis for evaluating changes in primary and secondary endpoints.

RESULTS

The mean age of the sample and time to first visit after discharge were 50.4±12.2 years and 362±105 days, respectively. A total of 11 (42.3%) were female. At baseline, the mean of peakVO₂, ventilatory efficiency and CIx were 18.9±5 mL/kg/min, 29.4±5.2 and 0.64±0.19, respectively. The IMT arm improved their peakVO₂ significantly compared with usual care (+Δ 4.46 mL/kg/min, 95% CI 3.10 to 5.81; p<0.001). Similar positive findings were found when evaluating changes for CI_x and some QoL dimensions. We did not find significant changes in ventilatory efficiency.

CONCLUSION

In long COVID patients with a previous admission due to SARS-CoV-2 pneumonia, IMT was associated with marked improvement in exercise capacity and QoL.

TRIAL REGISTRATION NUMBER

NCT05279430.

A multi-trial, retrospective analysis of the antihypertensive effects of high-resistance, low-volume inspiratory muscle strength training

Above-normal blood pressure (BP) is a primary risk factor for cardiovascular diseases. In a retrospective analysis of five pilot trials, we assessed the BP-lowering effects of high-resistance inspiratory muscle strength training (IMST) in adults aged 18-82 years and the impact of IMST on maximal inspiratory pressure (PIMAX), a gauge of inspiratory muscle strength and independent disease risk factor. Participants were randomized to high-resistance IMST (75% PIMAX) or low-resistance sham (15% PIMAX) training (30 breaths/day, 5-7 days/wk, 6 wk). IMST (n = 67) reduced systolic BP (SBP) by 9 ± 6 mmHg (P < 0.01) and diastolic BP (DBP) by 4 ± 4 mmHg (P < 0.01). IMST-related reductions in SBP and DBP emerged by week 2 of training (-4 ± 8 mmHg and -3 ± 6 mmHg; P ≤ 0.01, respectively) and continued across the 6-wk intervention. SBP and DBP were unchanged with sham training (n = 61, all P > 0.05). Select subject characteristics slightly modified the impact of IMST on BP. Greater reductions in SBP were associated with older age (β = -0.07 ± 0.03; P = 0.04) and greater reductions in DBP associated with medication-naïve BP (β = -3 ± 1; P = 0.02) and higher initial DBP (β = -0.12 ± 0.05; P = 0.04). PIMAX increased with high-resistance IMST and low-resistance sham training, with a greater increase from high-resistance IMST (+20 ± 17 vs. +6 ± 14 cmH2O; P < 0.01). Gains in PIMAX had a modest inverse relation with age (β = -0.20 ± 0.09; P = 0.03) and baseline PIMAX (β = -0.15 ± 0.07; P = 0.04) but not to reductions in SBP or DBP. These compiled findings from multiple independent trials provide the strongest evidence to date that high-resistance IMST evokes clinically significant reductions in SBP and DBP, and increases in PIMAX, in adult men and women.NEW & NOTEWORTHY In young-to-older adult men and women, 6 wk of high-resistance inspiratory muscle strength training lowers casual systolic and diastolic blood pressure by 9 mmHg and 4 mmHg, respectively, with initial reductions observed by week 2 of training. Given blood pressure outcomes with the intervention were only slightly altered by subject baseline characteristics (i.e., age, blood pressure medication, and health status), inspiratory muscle strength training is effective in lowering blood pressure in a broad range of adults.

Acute clavicle fixation after blunt chest trauma: effect on pulmonary outcomes and patient disposition

PURPOSE

Clavicle fractures are common in patients who sustain blunt chest trauma (BCT). Recently, surgical fixation of rib fractures in patients with BCT has been shown to improve pulmonary and clinical outcomes. Therefore, the purpose of this study is to assess the role of early clavicle fixation (ECF) versus non-operative (NO) treatment for midshaft clavicle fractures in this same population.

METHODS

A retrospective chart review was performed in patients with midshaft clavicle fractures and BCT at a Level I Trauma Center between 2007 and 2017. Patients with pre-existing pulmonary conditions and head injuries necessitating mechanical ventilation were excluded. Demographic data, injury mechanisms, and Thoracic Trauma Severity Scores (TTS) were analyzed. Inpatient pulmonary outcomes were assessed with serial vital capacity (VC) measurements, intubation, mechanical ventilation, and pulmonary complications data. In addition, intensive care unit (ICU) and hospital length of stay (LOS), mortality, discharge location, and incidence of postoperative complications in the ECF group were also measured.

RESULTS

Thirty-six patients underwent ECF, and 24 underwent NO treatment. The ECF cohort was statistically younger and had a greater incidence of clavicle fracture shortening than the NO group. There was no difference in pulmonary outcomes, ICU or hospital LOS, or mortality between groups. There were no complications associated with ECF. Patients who underwent ECF were more likely to discharge to home. There were no postoperative complications associated with ECF.

CONCLUSION

ECF of midshaft clavicle fractures does not improve pulmonary outcomes in patients with BCT. However, despite the lack of pulmonary benefit, there appears to be no added risk of harm. Therefore, ECF is a reasonable consideration in this patient population who otherwise meet clavicle fracture operative indications.

Effect of a home-based inspiratory muscular training programme on functional capacity in patients with chronic COVID-19 after a hospital discharge: protocol for a randomised control trial (InsCOVID trial)

Introduction

Exercise intolerance and fatigue are the most common symptoms in patients with chronic COVID-19 after hospital discharge. Supervised exercise training programmes improve symptoms, but scarce research has been done on home-based exercise programmes on the maximal functional capacity for discharged symptomatic COVID-19 patients. This study evaluates whether a home-based inspiratory muscle training (IMT) programme improves maximal functional capacity in chronic COVID-19 after hospital admission.

Methods and analysis

This single-centre, assessor-blinded randomised controlled trial, powered for superiority, seeks to evaluate maximal functional capacity as the primary endpoint. A total of 26 eligible patients with a previous admission for acute respiratory syndrome coronavirus 2 pneumonia (>3 months after hospital discharge) will be randomised (1:1) to receive a 12-week programme of IMT versus usual care alone. A blinded assessor will measure outcomes at baseline and after the intervention (12 weeks). An analysis of variance will be used to compare continuous outcomes among the two-intervention groups. As of 21 March 2022, eight patients have been enrolled.

Ethics and dissemination

The research ethics committee (Comité Ético de Investigación con Medicamentos de l'Hospital Clínic Universitari de València) approved the protocol following the principles of the Declaration of Helsinki and national regulations (Approval Number: 021/226). Findings will be published in peer-reviewed journals and conference publications.

Trial registration number

NCT05279430.

CO2-Enriched Air Inhalation Modulates the Ventilatory and Metabolic Responses of Endurance Runners During Incremental Running in Hypobaric Hypoxia

Cao, Yinhang, Naoto Fujii, Tomomi Fujimoto, Yin-Feng Lai, Takeshi Ogawa, Tsutomu Hiroyama, Yasushi Enomoto, and Takeshi Nishiyasu. CO₂-enriched air inhalation modulates the ventilatory and metabolic responses of endurance runners during incremental running in hypobaric hypoxia. High Alt Med Biol. 23:125-134, 2022. Aim: We measured the effects of breathing CO₂-enriched air on ventilatory and metabolic responses during incremental running exercise under moderately hypobairc hypoxic (HH) conditions. Materials and Methods: Ten young male endurance runners [61.4 ± 6.0 ml/(min·kg)] performed incremental running tests under three conditions: (1) normobaric normoxia (NN), (2) HH (2,500 m), and (3) HH with 5% CO₂ inhalation (HH+CO₂). The test under NN was always performed first, and then, the two remaining tests were completed in random and counterbalanced order. Results: End-tidal CO₂ partial pressure (55 ± 3 vs. 35 ± 1 mmHg), peak ventilation (163 ± 14 vs. 152 ± 12 l/min), and peak oxygen uptake [52.3 ± 5.5 vs. 50.5 ± 4.9 ml/(min·kg)] were all higher in the HH+CO₂ than HH trial (all p < 0.01), respectively. However, the duration of the incremental test did not differ between HH+CO₂ and HH trials. Conclusion: These data suggest that chemoreflex activation by breathing CO₂-enriched air stimulates breathing and aerobic metabolism during maximal intensity exercise without affecting exercise performance in male endurance runners under a moderately hypobaric hypoxic environment.

Time to Move Beyond a "One-Size Fits All" Approach to Inspiratory Muscle Training

Inspiratory muscle training (IMT) has been studied as a rehabilitation tool and ergogenic aid in clinical, athletic, and healthy populations. This technique aims to improve respiratory muscle strength and endurance, which has been seen to enhance respiratory pressure generation, respiratory muscle weakness, exercise capacity, and quality of life. However, the effects of IMT have been discrepant between populations, with some studies showing improvements with IMT and others not. This may be due to the use of standardized IMT protocols which are uniformly applied to all study participants without considering individual characteristics and training needs. As such, we suggest that research on IMT veer away from a standardized, one-size-fits-all intervention, and instead utilize specific IMT training protocols. In particular, a more personalized approach to an individual's training prescription based upon goals, needs, and desired outcomes of the patient or athlete. In order for the coach or practitioner to adjust and personalize a given IMT prescription for an individual, factors, such as frequency, duration, and modality will be influenced, thus inevitably affecting overall training load and adaptations for a projected outcome. Therefore, by integrating specific methods based on optimization, periodization, and personalization, further studies may overcome previous discrepancies within IMT research.

Influence of surgical stabilization of clavicle fractures in multiply-injured patients with thoracic trauma

Thoracic trauma has decisive influence on the outcome of multiply-injured patients and is often associated with clavicle fractures. The affected patients are prone to lung dysfunction and multiple organ failure. A multi-center, retrospective analysis of patient records documented in the TraumaRegister DGU was performed to assess the influence of surgical stabilization of clavicle fractures in patients with thoracic trauma. A total of 3,209 patients were included in the analysis. In 1362 patients (42%) the clavicle fracture was treated operatively after 7.1 ± 5.3 days. Surgically treated patients had a significant reduction in lung failure (p = 0.013, OR = 0.74), multiple organ failure (p = 0.001, OR = 0.64), intubation time (p = 0.004; -1.81 days) and length of hospital stay (p = 0.014; -1.51 days) compared to non-operative treatment. Moreover, surgical fixation of the clavicle within five days following hospital admission significantly reduced the rates of lung failure (p = 0.01, OR = 0.62), multiple organ failure (p = 0.01, OR = 0.59) and length of hospital stay (p = 0.01; -2.1 days). Based on our results, multiply-injured patients with thoracic trauma and concomitant clavicle fracture may benefit significantly from surgical stabilization of a clavicle fracture, especially when surgery is performed within the first five days after hospital admission.

Inspiratory muscle activation during inspiratory muscle training in patients with COPD

BACKGROUND AND OBJECTIVES

The main target of inspiratory muscle training (IMT) is to improve diaphragm function in patients with COPD who have inspiratory muscle weakness. Ventilatory demand is already increased during quiet breathing in patients with COPD, and whether threshold load imposed by IMT would active more accessory muscle remained to be determined. The purpose of this study was to examine diaphragm and sternocleidomastoid (SCM) activation during IMT with intensities of 30% and 50% maximal inspiratory pressure (P_Imax).

METHODS

Patients with COPD and a P_Imax lower than 60 cmH₂O were recruited for the study. Surface electromyography (EMG) was used to measure diaphragm and SCM activation, and group-based trajectory modeling (GBTM) was used to identify activation patterns during IMT. The generalized estimating equation (GEE) was then used to detect differences of variables between various breathing tasks. Statistical significance was established at p < 0.05.

RESULTS

A total of 30 patients with COPD participated in this study. All patients demonstrated significant increases in diaphragm and SCM activation during 30% and 50% P_Imax of IMT than during quiet breathing (all p < 0.001). Diaphragm demonstrated two distinct patterns in response to IMT: low activation (n = 8) and high activation (n = 22) group using GBTM analysis.

CONCLUSION

Diaphragm and SCM were substantially activated during IMT in patients with COPD who had inspiratory muscle weakness. Regardless of whether diaphragm activation was high or low, SCM was activated to a greater extent in response to IMT.

Respiratory muscle strength in volleyball players suffered from COVID-19

Background

Symptoms related to Coronavirus-19 disease (COVID-19) and quarantine measures have caused pulmonary function abnormality and impaired respiratory mechanics. However, no studies are evaluating pulmonary functions and respiratory muscle strength in female volleyball players according to COVID-19 status in the pandemic.

Aims

This study aims to compare pulmonary functions and respiratory muscle strength in female players with and without COVID-19.

Methods

Seventeen players (23.47 ± 5.89 years) who were recovered from COVID-19 and 25 female volleyball players (20.48 ± 5.05 years) who were not infected by SARS-CoV-2 were included in the study. Maximal inspiratory and expiratory pressure, pulmonary functions, body composition, symptom severity, and perceptions of performance were evaluated.

Results

Measured and predicted percent maximal inspiratory pressure and measured maximal expiratory pressure values of COVID-19 players were statistically significantly lower than non-COVID-19 players (p < 0.05). Dynamic lung volumes were similar in groups (p > 0.05).

Conclusions

Inspiratory and expiratory muscle strength in COVID-19 players were more affected compared with non-COVID-19 players. Pulmonary functions were mostly preserved in COVID-19 players. Respiratory muscle weakening can affect the performance of female players. Therefore, respiratory muscle strength training could be suggested in female players with COVID-19 to increase respiratory muscle strength and prevent deterioration in performance.

Trial registration (ClinicalTrials.gov)

Registration ID: NCT04789512.

Effect of end-inspiratory lung volume and breathing pattern on neural activation of the diaphragm and extra-diaphragmatic inspiratory muscles in healthy adults

This study examined the effect of changes in end-inspiratory lung volume (EILV) and breathing pattern on neural activation of the crural diaphragm (EMG_DIA) and of the sternocleidomastoid (EMG_SCM), scalene (EMG_SCA) and external intercostal muscles (EMG_INT) at constant ventilation (V̇_E). Twelve healthy adults performed a series of 30-sec breathing trials at a constant V̇_E corresponding to 15% of their maximum voluntary ventilation while (i) altering EILV at a constant breathing pattern and (ii) altering breathing pattern at a constant EILV. Using a real-time visual display of each participant's spirogram, EILV was voluntarily targeted at 65% (EILV_65%), 75% (EILV_75%), 85% (EILV_85%) and 95% (EILV_95%) of each participant's inspired vital capacity, while breathing frequency (f_R) was targeted at 15, 35 and 50 breaths/min using a metronome. The tidal volume needed for a participant to maintain V̇_E constant across trials was achieved via changes in end-expiratory lung volume. A multipair esophageal electrode catheter was used to record EMG_DIA, while surface electrodes were used to record EMG_SCM, EMG_SCA and EMG_INT. On average, EMG_DIA, EMG_SCM, EMG_SCA and EMG_INT increased as a function of increasing EILV at constant V̇_E, independent of changes in breathing pattern. The magnitudes of these increases were particularly notable in the transition from EILV_85% to EILV_95%, especially for EMG_SCM and EMG_SCA. In healthy adults, as EILV increases towards total lung capacity, progressive compensatory increases in neural activation of the diaphragm and extra-diaphragmatic inspiratory muscles are needed to support V̇_E, independent of changes in breathing pattern.

Case Studies in Physiology: Cardiopulmonary exercise testing and inspiratory muscle training in a 59-year-old, four years after an extra-pleural pneumonectomy

This case report characterizes the physiological responses to incremental cycling and determines the effects of 12 weeks of inspiratory muscle training (IMT) on respiratory muscle strength, exercise capacity and dyspnea in a physically active 59-year-old female, four years after a left-sided extra-pleural pneumonectomy (EPP). On separate days, a symptom limited incremental exercise test and a constant work rate (CWR) test at 75% of peak work rate (WR) were completed, followed by 12 weeks of IMT and another CWR test. IMT consisted of two sessions of 30 repetitions twice daily for 5 days per week. Physiological and perceptual variables were measured throughout each exercise test. The participant had a total lung capacity that was 43% predicted post-EPP. A rapid and shallow breathing pattern was adopted throughout exercise, and the ratio of minute ventilation to carbon dioxide output was elevated for a given work rate. Oxygen uptake was 74%predicted and WR was 88%predicted. Following IMT, maximal inspiratory pressure improved by 36% (-27.1 cmH₂O) and endurance time by 31s, with no observable changes in any submaximal or peak cardiorespiratory variables during exercise. The intensity and unpleasantness of dyspnea increased by 2 and 3 Borg 0-10 units, respectively, at the highest equivalent submaximal exercise time achieved on both tests. Despite having undergone a significant reduction in lung volume post-EPP, the participant achieved a relatively normal peak incremental WR, which may reflect a high level of physical conditioning. This case report also demonstrates that IMT can effectively increase respiratory muscle strength several years following EPP.

Features of electromyography threshold of the respiratory muscles during incremental exercise test

In this study, we aimed to examine the electromyography threshold (EMGT) of the respiratory muscle and accessory respiratory muscles. Sixteen healthy men underwent an incremental exercise test at 15 W/minute to the end point. Expired gases and electromyograms of the respiratory and lower limb muscles were measured. The breakpoints for the EMG and expired gas data were analyzed using a segmented regression model. EMGT of the sternocleidomastoid and diaphragm was significantly more delayed than the ventilation threshold (VT) (287.94 s, 288.15 s vs. 185.5 s, p = 0.028 and 0.044, respectively). The EMGT of respiratory muscles and VT were not related, though EMGT of rectus femoris and vastus lateralis correlated with VT (r = 0.854, p < 0.001; r = 0.657, p = 0.011, respectively). EMGT of respiratory muscles may be influenced by multiple factors, such as central command and afferent input of mechanical stimulation from muscles, in addition to VT-induced changes in metabolic dynamics.

Respiratory Muscle Strength: New Technology for Easy Assessment

Respiratory muscle strength (RMS) is associated with good functionality of the respiratory system. For the general population, it refers to the quality of life, and for the athletes, is related to greater performance. In this study, a comparison was made between two different portable devices, MicroRPM (CareFusion, Kent, United Kingdom) and AirOFit PRO™ (AirOFit, Copenhagen, Denmark), assessing the maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP). Twenty-one male professional athletes were evaluated on a voluntary basis and randomly used the devices for RMS assessment, while all athletes underwent Pittsburgh Sleep Quality Index (PSQI), pulmonary function tests and ergospirometry. All measurements of MIP and MEP were made with the same methodology and all participants after the efforts answered the question "easy-operation device-information" and dyspnea and/or respiratory fatigue during trials with the CR10 scale. Results showed statistical differences between VO_2max and maximal respiratory strength both for AirOFit PRO™ (r=0.526, p=0.014) and in MicroPRM (r=0.567, p=0.007). The PSQI score showed statistical differences in % of predicted values in MEP with the AirOFit PRO™ device (r=0.478, p=0.028). Athletes reported that the AirOFit PRO™ device is easier in operation as a device and provides more information during trial comparisons to MicroPRM (p=0.001). Athletes reported that the AirOFit PRO™ device is easier in operation as a device and provides more information during the trial compared to MicroPRM. The results did not show differences in RMS (MIP and MEP) between devices (p>0.05). For the people who want to train with tele-exercise and/or tele-rehabilitation, the AirOFit PRO™ device would be an important and safe training solution.

Acute thoracoabdominal and hemodynamic responses to tapered flow resistive loading in healthy adults

We investigated the acute physiological responses of tapered flow resistive loading (TFRL) at 30, 50 and 70 % maximal inspiratory pressure (PI_max) in 12 healthy adults to determine an optimal resistive load. Increased end-inspiratory rib cage and decreased end-expiratory abdominal volumes equally contributed to the expansion of thoracoabdominal tidal volume (captured by optoelectronic plethysmography). A significant decrease in end-expiratory thoracoabdominal volume was observed from 30 to 50 % PI_max, from 30 to 70 % PI_max, and from 50 to 70 % PImax. Cardiac output (recorded by cardio-impedance) increased from rest by 30 % across the three loading trials. Borg dyspnoea increased from 2.36 ± 0.20 at 30 % PI_max, to 3.45 ± 0.21 at 50 % PI_max, and 4.91 ± 0.25 at 70 % PI_max. End-tidal CO₂ decreased from rest during 30, 50 and 70 %PI_max (26.23 ± 0.59, 25.87 ± 1.02 and 24.30 ± 0.82 mmHg, respectively). Optimal intensity for TFRL is at 50 % PI_max to maximise global respiratory muscle and cardiovascular loading whilst minimising hyperventilation and breathlessness.

Differences in Respiratory Muscle Responses to Hyperpnea or Loaded Breathing in COPD

INTRODUCTION

We aimed to compare acute mechanical and metabolic responses of the diaphragm and rib cage inspiratory muscles during two different types of respiratory loading in patients with chronic obstructive pulmonary disease.

METHODS

In 16 patients (age, 65 ± 13 yr; 56% male; forced expiratory volume in the first second, 60 ± 6%pred; maximum inspiratory pressure, 82 ± 5%pred), assessments of respiratory muscle EMG, esophageal pressure (Pes) and gastric pressures, breathing pattern, and noninvasive assessments of systemic (V˙O2, cardiac output, oxygen delivery and extraction) and respiratory muscle hemodynamic and oxygenation responses (blood flow index, oxygen delivery index, deoxyhemoglobin concentration, and tissues oxygen saturation [StiO2]), were performed during hyperpnea and loaded breathing.

RESULTS

During hyperpnea, breathing frequency, minute ventilation, esophageal and diaphragm pressure-time product per minute, cardiac output, and V˙O2 were higher than during loaded breathing (P < 0.05). Average inspiratory Pes and transdiaphragmatic pressure per breath, scalene (SCA), sternocleidomastoid, and intercostal muscle activation were higher during loading breathing compared with hyperpnea (P < 0.05). Higher transdiaphragmatic pressure during loaded breathing compared with hyperpnea was mostly due to higher inspiratory Pes (P < 0.05). Diaphragm activation, inspiratory and expiratory gastric pressures, and rectus abdominis muscle activation did not differ between the two conditions (P > 0.05). SCA-blood flow index and oxygen delivery index were lower, and SCA-deoxyhemoglobin concentration was higher during loaded breathing compared with hyperpnea. Furthermore, SCA and intercostal muscle StiO2 were lower during loaded breathing compared with hyperpnea (P < 0.05).

CONCLUSION

Greater inspiratory muscle effort during loaded breathing evoked larger rib cage and neck muscle activation compared with hyperpnea. In addition, lower SCA and intercostal muscle StiO2 during loaded breathing compared with hyperpnea indicates a mismatch between inspiratory muscle oxygen delivery and utilization induced by the former condition.

Comparison between Two Inspiratory Muscle Training Protocols, Low Loads versus High Loads, in Institutionalized Elderly Women: A Double-Blind Randomized Controlled Trial

BACKGROUND

Aging results in a decline in the function of the respiratory muscles. Inspiratory muscle training is presented as a possible solution to attenuate the loss of respiratory function in the elderly. The objective of the study was to evaluate and compare the efficacy of 2 protocols with inspiratory muscle training (IMT), low loads and high loads, to improve respiratory strength, functional capacity and dyspnea in institutionalized elderly women, over 65 years.

METHODS

The study was a controlled, randomized, double-blind trial and with allocation concealment performed on 26 institutionalized elderly women distributed in 2 groups, the high-intensity group (HIG) and low-intensity group (LIG). Over an 8-week period an IMT protocol was followed 5 days/week, 15 min/day. The HIG trained with a load of 40% of the maximum inspiratory pressure (MIP) and the LIG with 20%. MIP, maximum expiratory pressure (MEP), functional capacity and dyspnea were evaluated.

RESULTS

After training, in the HIG MIP, MEP and functional capacity increased 52, 16 and 7%, respectively (p = 0.000, p = 0.001, p = 0.001) and in the LIG 30, 18 and 9%, respectively (p = 0.002, p = 0.014, p = 0.001). The improvement in MIP was significantly higher in the HIG than in the LIG (p = 0.042).

CONCLUSION

IMT with low and high loads improves respiratory muscle strength and functional capacity in institutionalized elderly women. In addition, high loads were significantly more effective to improve MIP.

Clinical Utility of Measuring Inspiratory Neural Drive During Cardiopulmonary Exercise Testing (CPET)

Cardiopulmonary exercise testing (CPET) has traditionally included ventilatory and metabolic measurements alongside electrocardiographic characterization; however, research increasingly acknowledges the utility of also measuring inspiratory neural drive (IND) through its surrogate measure of diaphragmatic electromyography (EMGdi). While true IND also encompasses the activation of non-diaphragmatic respiratory muscles, the current review focuses on diaphragmatic measurements, providing information about additional inspiratory muscle groups for context where appropriate. Evaluation of IND provides mechanistic insight into the origins of dyspnea and exercise limitation across pathologies; yields valuable information reflecting the integration of diverse mechanical, chemical, locomotor, and metabolic afferent signals; and can help assess the efficacy of therapeutic interventions. Further, IND measurement during the physiologic stress of exercise is uniquely poised to reveal the underpinnings of physiologic limitations masked during resting and unloaded breathing, with important information provided not only at peak exercise, but throughout exercise protocols. As our understanding of IND presentation across varying conditions continues to grow and methods for its measurement become more accessible, the translation of these principles into clinical settings is a logical next step in facilitating appropriate and nuanced management tailored to each individual's unique physiology. This review provides an overview of the current state of understanding of IND measurement during CPET: its origins, known patterns of behavior and links with dyspnea in health and major respiratory diseases, and the possibility of expanding this approach to applications beyond exercise.

Effectiveness of inspiratory muscle training on respiratory fitness and breathlessness in chronic renal failure: A randomized control trial

BACKGROUND

People with chronic renal failure (CRF) show decreased respiratory fitness and poor quality of life (QOL). Exercise during hemodialysis has been suggested to improve the cardio-respiratory fitness. However, results of effects of respiratory muscle (RM) training on respiratory fitness and QOL are inconsistent. In addition, very few studies explored the association between inspiratory muscle (IM) training and sensation of breathlessness.

OBJECTIVES

To examine the effects of IM training in hemodialysis patients on respiratory fitness QOL and breathlessness.

METHOD

A randomized control trial with 50 CRF, who underwent hemodialysis (25 individuals in each group; IM training and sham group) was designed. Pulmonary function, RM strength, QOL (measured by Kidney Disease Quality of Life-36), and sensation of breathlessness were measured before and after an 8-week intervention.

RESULTS

Compared to the sham group, the IM strength increased in the intervention group after an 8-week program (Δ25.92 ± 8.73 cmH₂ O, p = 0.005). Significantly increased IM and forced vital capacity values in training groups was observed after an 8-week intervention (Δ12.44 ± 3.07 cmH₂ O and Δ0.097 ± 0.046 L, respectively), but not the sham group. Neither, the training group, nor the sham group were significantly different in the QOL. However, feeling of shortness of breath improved after the training program among inspiratory muscle training group, but not the sham group.

CONCLUSION

IM training during hemodialysis could lead to an improvement of respiratory fitness and reduce breathlessness in people with CRF who are receiving hemodialysis. However, QOL was not different after the training program. The study suggests that after 8-week intervention program, IM training (loading exercise) could improve IM strength, pulmonary function without any complications during the intervention program within 1-2 h.

Pulmonary rehabilitation and exercise therapy in a patient with COVID-19: A Case report

Dyspnea, shortness of breath, and inability to perform activities of daily living are the main complaints in patients with COVID-19 and physiotherapy has a vital role in managing such symptoms. We present a case treated with pulmonary and neurological physiotherapy, which improved symptoms and quality of life. In this case report, the importance and potential effect of concise physiotherapy on patients with COVID-19 is presented.

Surface respiratory electromyography and dyspnea in acute heart failure patients

Introduction and Objectives: Dyspnea is the most common symptom among hospitalized patients with heart failure (HF) but besides dyspnea questionnaires (which reflect the subjective patient sensation and are not fully validated in HF) there are no measurable physiological variables providing objective assessment of dyspnea in a setting of acute HF patients. Studies performed in respiratory patients suggest that the measurement of electromyographic (EMG) activity of the respiratory muscles with surface electrodes correlates well with dyspnea. Our aim was to test the hypothesis that respiratory muscles EMG activity is a potential marker of dyspnea severity in acute HF patients. Methods: Prospective and descriptive pilot study carried out in 25 adult patients admitted for acute HF. Measurements were carried out with a cardio-respiratory portable polygraph including EMG surface electrodes for measuring the activity of main (diaphragm) and accessory (scalene and pectoralis minor) respiratory muscles. Dyspnea sensation was assessed by means of the Likert 5 questionnaire. Data were recorded during 3 min of spontaneous breathing and after breathing at maximum effort for several cycles for normalizing data. An index to quantify the activity of each respiratory muscle was computed. This assessment was carried out within the first 24 h of admission, and at day 2 and 5. Results: Dyspnea score decreased along the three measured days. Diaphragm and scalene EMG index showed a positive and significant direct relationship with dyspnea score (p<0.001 and p = 0.003 respectively) whereas pectoralis minor muscle did not. Conclusion: In our pilot study, diaphragm and scalene EMG activity was associated with increasing severity of dyspnea. Surface respiratory EMG could be a useful objective tool to improve assessment of dyspnea in acute HF patients.

Effect of inspiratory resistive training on diaphragm shear modulus and accessory inspiratory muscle activation

This study aimed to elucidate changes in diaphragm and accessory inspiratory muscle (sternocleidomastoid (SCM) muscle and intercostal muscle (IC)) function after a 6-week training program. Nineteen male elite collegiate swimmers were assigned to either a control group (n = 9) or training group (n = 10). The subjects in the training group performed 30 maximum inspirations at a load resistance of 50% of maximum inspiratory mouth pressure (PImax) using an inspiratory muscle training device. These were conducted twice per day and 6 days per week. At baseline and after 6 weeks, PImax, shear modulus of the diaphragm, and electromyograms (EMG) of the SCM and IC during a maximal inspiratory maneuver were evaluated. Relative change in PImax was greater in the training group than in controls. The shear modulus during a PImax maneuver had increased significantly in both groups after 6 weeks. EMG amplitudes of the SCM increased in the training group after 6 weeks, but not in the control group. EMG amplitudes of the IC did not change after 6 weeks in either group. These results suggest that 6-week inspiratory resistive training significantly improves the activation of the SCM, which could be one of the major mechanisms behind increases in inspiratory muscle strength after resistive training. Novelty Six-week inspiratory resistive training increased diaphragm stiffness during maximal inspiration maneuver. Six-week inspiratory resistive training increased electromyogram amplitudes of the sternocleidomastoid during maximal inspiration maneuver.

Manipulation of mechanical ventilatory constraint during moderate intensity exercise does not influence dyspnoea in healthy older men and women

KEY POINTS

The perceived intensity of exertional breathlessness (i.e. dyspnoea) is higher in older women than in older men, possibly as a result of sex-differences in respiratory system morphology. During exercise at a given absolute intensity or minute ventilation, older women have a greater degree of mechanical ventilatory constraint (i.e. work of breathing and expiratory flow limitation) than their male counterparts, which may lead to a greater perceived intensity of dyspnoea. Using a single-blind randomized study design, we experimentally manipulated the magnitude of mechanical ventilatory constraint during moderate-intensity exercise at ventilatory threshold in healthy older men and women. We found that changes in the magnitude of mechanical ventilatory constraint within the physiological range had no effect on dyspnoea in healthy older adults. When older men and women perform moderate intensity exercise, mechanical ventilatory constraint does not contribute significantly to the sensation of dyspnoea.

ABSTRACT

We aimed to determine the effect of manipulating mechanical ventilatory constraint during submaximal exercise on dyspnoea in older men and women. Eighteen healthy subjects (aged 60-80 years; nine men and nine women) completed two days of testing. On day 1, subjects were assessed for pulmonary function and performed a maximal incremental cycle exercise test. On day 2, subjects performed three 6-min bouts of cycling at ventilatory threshold, in a single-blind randomized manner, while breathing: (i) normoxic helium-oxygen (HEL) to reduce the work of breathing (W_b ) and alleviate expiratory flow limitation (EFL); (ii) through an inspiratory resistance (RES) of ∼5 cmH₂ O L^-1  s^-1 to increase W_b ; and (iii) ambient air as a control (CON). Oesophageal pressure, diaphragm electromyography, and sensory responses (category-ratio 10 Borg scale) were monitored throughout exercise. During the HEL condition, there was a significant decrease in W_b (men: -21 ± 6%, women: -17 ± 10%) relative to CON (both P < 0.01). Moreover, if EFL was present during CON (four men and five women), it was alleviated during HEL. Conversely, during the RES condition, W_b (men: 42 ± 19%, women: 50 ± 16%) significantly increased relative to CON (both P < 0.01). There was no main effect of sex on W_b (P = 0.59). Across conditions, women reported significantly higher dyspnoea intensity than men (2.9 ± 0.9 vs. 1.9 ± 0.8 Borg scale units, P < 0.05). Despite significant differences in the degree of mechanical ventilatory constraint between conditions, the intensity of dyspnoea was unaffected, independent of sex (P = 0.46). When older men and women perform moderate intensity exercise, mechanical ventilatory constraint does not contribute significantly to the sensation of dyspnoea.

Surface electromyography in inspiratory muscles in adults and elderly individuals: A systematic review

INTRODUCTION

Electromyography (EMG) helps to evaluate disorders and pulmonary behavior, as impairments in respiratory muscle function are associated with the development of diseases. There is a wide range of methods and protocols used to record and analyze EMG obtained from respiratory muscles, demonstrating a lack of standardization.

OBJECTIVE

To identify the most common procedures used to record surface EMG (sEMG) of inspiratory muscles in adults and elderly individuals through a systematic review (primary), and to evaluate the quality of the report presented by the studies (secondary).

METHOD

Studies published from January 1995 until June 2018 were searched for in the Web of Science, PubMed, LILACS, EBSCO and Embase databases. Only studies evaluating sEMG of inspiratory muscles were included.

RESULTS

The electronic search retrieved a total of 6697 titles and 92 of them were included. A great variability on the methods applied to both recording and processing/analyzing data was found. Therefore, the synthesis of practical/clinical evidence to support immediate recommendations was impaired. In general, the descriptions presented by the studies are poor.

CONCLUSION

The most common procedures used for sEMG were identified. Methodological studies with objective comparisons were fundamental for improving standardization, given the impossibility of recommendations from this review.

The application of ECG cancellation in diaphragmatic electromyographic by using stationary wavelet transform

In this paper, we present and investigate a special kind of stationary wavelet algorithm using "inverse" hard threshold to eliminate the electrocardiogram (ECG) interference included in diaphragmatic electromyographic (EMGdi). Differing from traditional wavelet hard threshold, "inverse" hard threshold is used to shrink strong coefficients of ECG interference and reserve weak coefficients of EMGdi signal. Meanwhile, a novel QRS location algorithm is proposed for the position detection of R wave by using low frequency coefficients in this paper. With the proposed method, raw EMGdi is decomposed by wavelet at fifth scale. Then, each ECG interference threshold is calculated by mean square, which is estimated by wavelet coefficients in the ECG cycle at each level. Finally, ECG interference wavelet coefficients are removed by "inverse" hard threshold, and then the de-noised signal is reconstructed by wavelet coefficients. The simulation and clinical EMGdi de-noising results show that the "inverse" hard threshold investigated in this paper removes the ECG interference in EMGdi availably and reserves its signal characteristics effectively, as compared to wavelet threshold.

Recent Advancements in Our Understanding of the Ergogenic Effect of Respiratory Muscle Training in Healthy Humans: A Systematic Review

Shei, R-J. Recent advancements in our understanding of the ergogenic effect of respiratory muscle training in healthy humans: a systematic review. J Strength Cond Res 32(9): 2674-2685, 2018-Respiratory muscle training (RMT) has been shown to be an effective ergogenic aid for sport performance. Respiratory muscle training has been documented to improve performance in a wide range of exercise modalities including running, cycling, swimming, and rowing. The physiological effects of RMT that may explain the improvements in performance have been proposed to include diaphragm hypertrophy, muscle fiber-type switching, improved neural control of the respiratory muscles, increased respiratory muscle economy, attenuation of the respiratory muscle metaboreflex, and decreases in perceived breathlessness and exertion. This review summarizes recent studies on the ergogenicity and mechanisms of RMT since 2013 when the topic was last systematically reviewed. Recent evidence confirms the ergogenic effects of RMT and explores different loading protocols, such as concurrent exercise and RMT (i.e., "functional" RMT). These studies suggest that adapting new training protocols may have an additive improvement effect, but evidence of the efficacy of such an approach is conflicting thus far. Other recent investigations have furthered our understanding of the mechanisms underpinning RMT-associated improvements in performance. Importantly, changes in ventilatory efficiency, oxygen delivery, cytokine release, motor recruitment patterns, and respiratory muscle fatigue resistance are highlighted as potential mechanistic factors linking RMT with performance improvements. It is suggested that future investigations focus on development of sport-specific RMT loading protocols, and that further work be undertaken to better understand the mechanistic basis of RMT-induced performance improvements.

Inspiratory muscle training reduces diaphragm activation and dyspnea during exercise in COPD

Among patients with chronic obstructive pulmonary disease (COPD), those with the lowest maximal inspiratory pressures experience greater breathing discomfort (dyspnea) during exercise. In such individuals, inspiratory muscle training (IMT) may be associated with improvement of dyspnea, but the mechanisms for this are poorly understood. Therefore, we aimed to identify physiological mechanisms of improvement in dyspnea and exercise endurance following inspiratory muscle training (IMT) in patients with COPD and low maximal inspiratory pressure (Pi_max). The effects of 8 wk of controlled IMT on respiratory muscle function, dyspnea, respiratory mechanics, and diaphragm electromyography (EMGdi) during constant work rate cycle exercise were evaluated in patients with activity-related dyspnea (baseline dyspnea index <9). Subjects were randomized to either IMT or a sham training control group ( n = 10 each). Twenty subjects (FEV₁ = 47 ± 19% predicted; Pi_max  = -59 ± 14 cmH₂O; cycle ergometer peak work rate = 47 ± 21% predicted) completed the study; groups had comparable baseline lung function, respiratory muscle strength, activity-related dyspnea, and exercise capacity. IMT, compared with control, was associated with greater increases in inspiratory muscle strength and endurance, with attendant improvements in exertional dyspnea and exercise endurance time (all P < 0.05). After IMT, EMGdi expressed relative to its maximum (EMGdi/EMGdi_max) decreased ( P < 0.05) with no significant change in ventilation, tidal inspiratory pressures, breathing pattern, or operating lung volumes during exercise. In conclusion, IMT improved inspiratory muscle strength and endurance in mechanically compromised patients with COPD and low Pi_max. The attendant reduction in EMGdi/EMGdi_max helped explain the decrease in perceived respiratory discomfort despite sustained high ventilation and intrinsic mechanical loading over a longer exercise duration. NEW & NOTEWORTHY In patients with COPD and low maximal inspiratory pressures, inspiratory muscle training (IMT) may be associated with improvement of dyspnea, but the mechanisms for this are poorly understood. This study showed that 8 wk of home-based, partially supervised IMT improved respiratory muscle strength and endurance, dyspnea, and exercise endurance. Dyspnea relief occurred in conjunction with a reduced activation of the diaphragm relative to maximum in the absence of significant changes in ventilation, breathing pattern, and operating lung volumes.

Association of physical activity with lung function in lung-healthy German adults: results from the KORA FF4 study

BACKGROUND

In lung disease, physical activity (PA) yields beneficial health effects, but its association with the function of healthy lungs has rarely been studied. We investigated the association of accelerometer-based PA with spirometric indices, maximal inspiratory mouth pressure (PI_max) and lung diffusion capacity in lung-healthy adults.

METHODS

In total, 341 apparently lung-healthy participants from the population-based KORA (Cooperative Health Research in the Region of Augsburg) FF4 cohort study (45% male, aged 48-68 years, 47% never smokers) completed lung function testing and wore ActiGraph accelerometers over a one week period at the hip. In adjusted regression analyses, moderate to vigorous PA (MVPA) was characterized as: sex-specific activity quartiles, achieving ≥ 10 consecutive minutes (yes vs. no), and meeting the WHO PA recommendations (yes vs. no).

RESULTS

Positive associations of MVPA-quartiles with forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), and corresponding Global Lung Function Initiative z-scores were found. Subjects in the most active quartile (> 47 or > 50 min/day for females and males, respectively) had 142 ml [95% CI: 23, 260] higher FEV₁ and 155 ml [95% CI: 10, 301] higher FVC than those in the least active quartile (< 17 or < 21 min/day for females and males, respectively); however these associations were stronger among ex-/current smokers. Achieving at least once 10 consecutive minutes of MVPA was only associated with higher PI_max [β-estimate: 0.57 kPa; 95% CI: 0.04, 1.10], remaining significant among never smokers. No associations were found with diffusion capacity or for reaching the WHO-recommended 150 min of MVPA/week in 10-min bouts.

CONCLUSIONS

Although the effects were small, active subjects showed higher spirometric results. The observed associations were more pronounced among ever smokers suggesting a higher benefit of PA for subjects being at a higher risk for chronic lung diseases.