The importance of quantifying training loads and applying exercise principles in respiratory muscle training studies

Mechanisms of improved exercise capacity following respiratory muscle training in athletes with cervical spinal cord injury.

Respiratory muscle training is a structured intervention targeting the respiratory muscles, yet its effect on chronic stroke patients remains unclear. The study evaluated the influence of this training on respiratory function, exercise capacity and quality of life among individuals who experienced chronic strokes. This study adhered to the PRISMA statement guidelines. A comprehensive search of databases including PubMed, Embase, AMED, CINAHL, Cochrane Library, and Web of Science was conducted without date limitations, extending until 8 March 2025. The search targeted randomised controlled trials that involved: 1) chronic stroke patients (≥18 years, diagnosed for >3 months), 2) respiratory muscle training encompasses both inspiratory and expiratory muscle training, and 3) outcomes measuring the strength and endurance of respiratory muscle, pulmonary function testing, exercise capacity, and quality of life. Two separate reviewers conducted the screening for eligibility, gathered data, and evaluated both the methodological quality and potential risk of bias. Meta-analyses utilized RevMan version 5.4 (Cochrane Collaboration, United Kingdom), applying random-effects models to calculate mean difference (MD), standardized mean difference (SMD), and corresponding 95% confidence intervals (95% CI). Nine studies were included, comprising 288 participants (143 males and 145 females) with a mean age of 58.5 years. For primary outcomes, respiratory muscle training significantly enhanced maximal inspiratory pressure (MD = 17.71 cmH2O, 95% CI: 10.19-25.23) and respiratory muscle endurance (MD = 20.58 cmH2O, 95% CI: 12.25-28.92) among chronic stroke patients, but no significant effects were observed for maximal expiratory pressure (MD = 11.37 cmH2O, 95% CI: -0.78-25.23). The subgroup analysis revealed that the combination of inspiratory muscle training and expiratory muscle training enhanced maximal inspiratory pressure (MD = 23.47 cmH2O, 95% CI: 3.65-43.30) and respiratory muscle endurance (MD = 34.00 cmH2O, 95% CI: 21.21-46.79), while inspiratory muscle training improved maximal inspiratory pressure (MD = 14.09 cmH2O, 95% CI: 7.57-20.62), maximal expiratory pressure (MD = 8.69 cmH2O, 95% CI: 0.63-16.75), and respiratory muscle endurance (MD = 16.69 cmH2O, 95% CI: 10.27-23.11). For secondary outcomes, significant improvements occurred in forced expiratory volume in 1s (MD = 0.25 L, 95% CI: 0.06-0.44) and peak expiratory flow (MD = 0.84 L/s, 95% CI: 0.31-1.37), but not in forced vital capacity (MD = 0.16 L, 95% CI: -0.08-0.41), exercise capacity (SMD = 0.29, 95% CI: -0.03-0.61), and quality of life. Respiratory muscle training effectively enhances primary outcomes, including maximal inspiratory pressure and respiratory muscle endurance, as well as secondary outcomes such as forced expiratory volume in 1s and peak expiratory flow in chronic stroke patients, but does not improve maximal expiratory pressure, forced vital capacity, exercise capacity, and quality of life. The combination of inspiratory muscle training with expiratory muscle training, as well as inspiratory muscle training alone, can enhance maximal inspiratory pressure and the endurance of respiratory muscles. Furthermore, inspiratory muscle training alone can improve maximal expiratory pressure. identifier, CRD42024517859.

Inspiratory Muscle Training Improves Shuttle Run Performance in Healthy Subjects

The respiratory system has traditionally been viewed to be capable of meeting the substantial demands for ventilation and gas exchange and the cardiopulmonary interactions imposed by short-term maximum exercise or long-term endurance exercise. Recent studies suggest that specific respiratory muscle (RM) training can improve the endurance and strength of the respiratory muscles in healthy humans. The effects of RM training on exercise performance remains controversial. When whole-body exercise performance is evaluated using submaximal fixed work-rate tests, significant improvements are seen and smaller, but significant improvements have also been reported in placebo-trained individuals. When performance is measured using time-trial type performance measures versus fixed workload tests, performance is increased to a much lesser extent with RM training. It appears that RM training influences relevant measures of physical performance to a limited extent at most. Interpretation of the collective literature is difficult because most studies have utilised relatively small sample sizes and very few studies have used appropriate control or placebo groups. Mechanisms to explain the purported improvements in exercise performance remain largely unknown. However, possible candidates include improved ratings of breathing perception, delay of respiratory muscle fatigue, ventilatory efficiency, or blood-flow competition between respiratory and locomotor muscles. This review summarises the current literature on the physiology of RM training in healthy individuals and critically evaluates the possible implications for exercise performance.

A consistent finding of recent research on respiratory muscle training (RMT) in healthy humans has been an attenuation of respiratory discomfort (dyspnoea) during exercise. We argue that the neurophysiology of dyspnoea can be explained in terms of Cambell's paradigm of length-tension inappropriateness. In the context of this paradigm, changes in the contractile properties of the respiratory muscles modify the intensity of dyspnoea predominantly by changing the required level of motor outflow to these respiratory muscles. Thus, factors that impair the contractile properties of the respiratory muscles (e.g. the pattern of tension development, functional weakening and fatigue) have the potential to increase the intensity of dyspnoea, while factors that improve the contractile properties of these respiratory muscles (e.g. RMT) have the potential to reduce the intensity of dyspnoea. In patients with obstructive pulmonary disease, functional weakening of the inspiratory muscles in response to dynamic lung hyperinflation appears to be a central component of dyspnoea. A decrease in the intensity of respiratory effort sensation (during exercise and loaded breathing) has been observed in both healthy individuals and patients with obstructive pulmonary disease after RMT. We conclude that RMT has the potential to reduce the severity of dyspnoea in healthy individuals and in patients with obstructive pulmonary disease, and that this probably occurs via a reduction in the level of motor outflow. Further work is required to clarify the role of RMT in the management of other disease conditions in which the function of the respiratory muscles is impaired, or the loads that they must overcome are elevated (e.g. cardiorespiratory and neuromuscular disorders).

RMT may improve lung capacity and respiratory muscle strength in some NMDs. In ALS there may not be any clinically meaningful effect of RMT on physical functioning or quality of life and it is uncertain whether it causes adverse effects. Due to clinical heterogeneity between the trials and the small number of participants included in the analysis, together with the risk of bias, these results must be interpreted very cautiously.

Effect of high-intensity home-based respiratory muscle training on strength of respiratory muscles following a stroke: a protocol for a randomized controlled trial

We undertook two systematic reviews to determine the levels of respiratory muscle weakness and effects of respiratory muscle training in stroke patients. Two systematic reviews were conducted in June 2011 using a number of electronic databases. Review 1 compared respiratory muscle strength in stroke and healthy controls. Review 2 was expanded to include randomized controlled trials assessing the effects of respiratory muscle training on stroke and other neurological conditions. The primary outcomes of interest were maximum inspiratory and expiratory mouth pressure (maximum inspiratory pressure and maximum expiratory pressure, respectively). Meta-analysis of four studies revealed that the maximum inspiratory pressure and maximum expiratory pressure were significantly lower (P < 0·00001) in stroke patients compared with healthy individuals (weighted mean difference -41·39 and -54·62 cmH(2) O, respectively). Nine randomized controlled trials indicate a significantly (P = 0·0009) greater effect of respiratory muscle training on maximum inspiratory pressure in neurological patients compared with control subjects (weighted mean difference 6·94 cmH(2) O) while no effect on maximum expiratory pressure. Respiratory muscle strength appears to be impaired after stroke, possibly contributing to increased incidence of chest infection. Respiratory muscle training can improve inspiratory but not expiratory muscle strength in neurological conditions, although the paucity of studies in the area and considerable variability between them is a limiting factor. Respiratory muscle training may improve respiratory muscle function in neurological conditions, but its clinical benefit remains unknown.

RMT may improve lung capacity and respiratory muscle strength in some NMDs. In ALS there may not be any clinically meaningful effect of RMT on physical functioning or quality of life and it is uncertain whether it causes adverse effects. Due to clinical heterogeneity between the trials and the small number of participants included in the analysis, together with the risk of bias, these results must be interpreted very cautiously.

COPD is characterized not only by pulmonary pathology but also by systemic disorders leading to abrupt reduction in physical tolerance causing a significant decrease in the patients' quality of life (QoL). Training of upper and lower limb muscles along with breathing training, training of respiratory muscles using respiratory training devices and adequate drug therapy can improve physical tolerance of COPD patients. The aim of this work was to compare different methods of physical rehabilitation under the therapy with tiotropium bromide (TB). The study involved 45 patients with severe and very severe COPD (the mean age, 64.5 ±11.0 yrs) randomized into 3 groups: the 1st group patients took inhaled corticosteroids (ICS), short-acting b-agonists and TB, the 2nd group patients were treated with the same medications plus respiratory muscle training with Threshold IMT, PEP, and the 3rd group received the same medications plus skeletal muscle training. The study continued for 3 months and included 3 active visits with testing of lung function (LF) and respiratory muscle strength (Pi, Pe), 6-minute walking test (6-MWT), evaluation of QoL using the SF-36 questionnaire and of dyspnea using MRC scale. As a result, all groups have improved QoL, LF, respiratory muscle strength, and 6-minute walk distance after 3-month treatment. The best values of QoL and 6-MWT were seen in the 3rd group. The greatest improvement for the 2nd group patients was noted in LF and respiratory muscle strength. The 1st group also improved all the parameters. Therefore, we can not exclude the effect of TB on physical tolerance in COPD patients. We conclude that combined application of respiratory and skeletal muscle training and drug therapy including TB is the optimal treatment for COPD patients.

BackgroundRespiratory muscle training is a continuous and standardized training of respiratory muscles, but the evidence of the effects on early stroke patients is not clear. This meta-analysis aimed to investigate the effects of respiratory muscle training on respiratory function and functional capacity in patients with early stroke.MethodsPubMed, Embase, PEDro, ScienceDirect, AMED, CINAHL, and China National Knowledge Infrastructure databases were searched from inception to December 8, 2023 for articles about studies that 1) stroke patients with age ≥ 18 years old. Early stroke < 3 months at the time of diagnosis, 2) respiratory muscle training, including inspiratory and expiratory muscle training, 3) the following measurements are the outcomes: respiratory muscle strength, respiratory muscle endurance, pulmonary function testing, dyspnea fatigue score, and functional capacity, 4) randomized controlled trials. Studies that met the inclusion criteria were extracted data and appraised the methodological quality and risk of bias using the Physiotherapy Evidence Database scale and the Cochrane Risk of Bias tool by two independent reviewers. RevMan 5.4 with a random effect model was used for data synthesis and analysis. Mean differences (MD) or standard mean differences (SMD), and 95% confidence interval were calculated (95%CI).ResultsNine studies met inclusion criteria, recruiting 526 participants (mean age 61.6 years). Respiratory muscle training produced a statistically significant effect on improving maximal inspiratory pressure (MD = 10.93, 95%CI: 8.51–13.36), maximal expiratory pressure (MD = 9.01, 95%CI: 5.34–12.69), forced vital capacity (MD = 0.82, 95%CI: 0.54–1.10), peak expiratory flow (MD = 1.28, 95%CI: 0.94–1.63), forced expiratory volume in 1 s (MD = 1.36, 95%CI: 1.13–1.59), functional capacity (SMD = 0.51, 95%CI: 0.05–0.98) in patients with early stroke. Subgroup analysis showed that inspiratory muscle training combined with expiratory muscle training was beneficial to the recovery of maximal inspiratory pressure (MD = 9.78, 95%CI: 5.96–13.60), maximal expiratory pressure (MD = 11.62, 95%CI: 3.80–19.43), forced vital capacity (MD = 0.87, 95%CI: 0.47–1.27), peak expiratory flow (MD = 1.51, 95%CI: 1.22–1.80), forced expiratory volume in 1 s (MD = 0.76, 95%CI: 0.41–1.11), functional capacity (SMD = 0.61, 95%CI: 0.08–1.13), while inspiratory muscle training could improve maximal inspiratory pressure (MD = 11.60, 95%CI: 8.15–15.05), maximal expiratory pressure (MD = 7.06, 95%CI: 3.50–10.62), forced vital capacity (MD = 0.71, 95%CI: 0.21–1.21), peak expiratory flow (MD = 0.84, 95%CI: 0.37–1.31), forced expiratory volume in 1 s (MD = 0.40, 95%CI: 0.08–0.72).ConclusionsThis study provides good-quality evidence that respiratory muscle training is effective in improving respiratory muscle strength, pulmonary function, and functional capacity for patients with early stroke. Inspiratory muscle training combined with expiratory muscle training seems to promote functional recovery in patients with early stroke more than inspiratory muscle training alone.Trial registrationProspero registration number: CRD42021291918.

Objective To explore the influence of resistive respiratory training for patients with chronic obstructive pulmonary disease（COPD） on rehabilitation effect.Methods According to the digital table,68 COPD patients were randomly divided into the observation group and control group,34 cases each group.The observation group were taken respiratory muscle training under the supervision of rehabilitation nurses for 8 weeks,and the respir-atory muscle training including shrinkage lip diaphragm breathing training and abdominal muscle resistance training. Before and after the abdominal muscle resistance training and training were given 1 h double nasal oxygen tube contin-uous low flow oxygen inhalation.The control group were taken pursed lips abdominal breathing training.In the two groups before treatment and 8 weeks after, the blood gas analysis （ PaO2 , PaCO2 ） , pulmonary function test （ FEV1 , FEV1/FVC%） and respiratory muscle function（ MIP,MEP） were detected.Results After treatment,blood gas anal-ysis in the two groups comparison（tPaO2 =2.95,tPaCO2 =2.07）,pulmonary function（tFEV1 =2.38,tFEV1/FVC%=2.04） and respiratory muscle physiology index（tMIP =6.40,tMEP =4.04）,the differences were statistically （all P〈0.05）.In the observed group before and after treatment,blood gas analysis（tPaO2 =19.23,tPaCO2 =3.05）,pulmonary function（tFEV1 =2.67,tFEV1/FVC%=4.19）and respiratory muscle physiology index（tMIP=9.09,tMEP=9.67） were compared,the differences were statistically（all P〈0.01）.Conclusion Respiratory mus-cle resistance training can improve COPD patients with respiratory muscle strength and endurance,and it has the cura-tive effect to improve pulmonary function. Key words: Pulmonary Disease; Chronic Obstructive Respiratory Muscles Breathing Exercises Rehabilita-tion

Entrenamiento de los músculos respiratorios: ¿sí o no?

BackgroundSpinal Muscular Atrophy (SMA) is characterized by progressive and predominantly proximal and axial muscle atrophy and weakness. Respiratory muscle weakness results in impaired cough with recurrent respiratory tract infections, nocturnal hypoventilation, and may ultimately lead to fatal respiratory failure in the most severely affected patients. Treatment strategies to either slow down the decline or improve respiratory muscle function are wanting.ObjectiveThe aim of this study is to assess the feasibility and efficacy of respiratory muscle training (RMT) in patients with SMA and respiratory muscle weakness.MethodsThe effect of RMT in patients with SMA, aged ≥ 8 years with respiratory muscle weakness (maximum inspiratory mouth pressure [PImax] ≤ 80 Centimeters of Water Column [cmH2O]), will be investigated with a single blinded randomized sham-controlled trial consisting of a 4-month training period followed by an 8-month open label extension phase.InterventionThe RMT program will consist of a home-based, individualized training program involving 30-breathing cycles through an inspiratory and expiratory muscle training device. Patients will be instructed to perform 10 training sessions over 5–7 days per week. In the active training group, the inspiratory and expiratory threshold will be adjusted to perceived exertion (measured on a Borg scale). The sham-control group will initially receive RMT at the same frequency but against a constant, non-therapeutic resistance. After four months the sham-control group will undergo the same intervention as the active training group (i.e., delayed intervention). Individual adherence to the RMT protocol will be reviewed every two weeks by telephone/video call with a physiotherapist.Main study parameters/endpointsWe hypothesize that the RMT program will be feasible (good adherence and good acceptability) and improve inspiratory muscle strength (primary outcome measure) and expiratory muscle strength (key secondary outcome measure) as well as lung function, patient reported breathing difficulties, respiratory infections, and health related quality of life (additional secondary outcome measures, respectively) in patients with SMA.DiscussionRMT is expected to have positive effects on respiratory muscle strength in patients with SMA. Integrating RMT with recently introduced genetic therapies for SMA may improve respiratory muscle strength in this patient population.Trial registrationRetrospectively registered at clinicaltrial.gov: NCT05632666.

The effect of combined inspiratory and expiratory muscle training on resting and reflexive cardiac function, as well as exercise capacity, in individuals with cervical spinal cord injury (SCI) is presently unknown. Six weeks of combined inspiratory and expiratory muscle training enhances both inspiratory and expiratory muscle strength in highly-trained athletes with cervical SCI with no significant effect on lung function. There was a significant decrease in left-ventricular filling and stroke volume at rest in response to 45° head-up tilt, which is irreversible by respiratory muscle training. Combined inspiratory and expiratory muscle training increased peak aerobic work rate and reduced end-expiratory lung volumes during exercise, which may have implications for left-ventricular filling during exercise. To investigate the pulmonary, cardiovascular and exercise responses to combined inspiratory and expiratory respiratory muscle training (RMT) in athletes with tetraplegia, six wheelchair rugby athletes (five males and one female, aged 33±5years) completed 6weeks of pressure threshold RMT, 2 sessionsday-1 on 5daysweek-1 . Resting pulmonary and cardiac function, exercise capacity, exercising lung volumes and field-based exercise performance were assessed at pre-RMT, post-RMT and after a 6-week no RMT period. RMT enhanced maximal inspiratory (pre- vs. post-RMT: -76±15 to -106±23cmH2 O, P=0.002) and expiratory (59±26 to 73±32cmH2 O, P=0.007) mouth pressures, as well as peak expiratory flow (6.74±1.51vs. 7.32±1.60L/s, P<0.04). Compared to pre-RMT, peak work rate was higher at post-RMT (60±23 to 68±22W, P=0.003), whereas exercising end-expiratory lung volumes were reduced (P<0.017). Peak oxygen uptake increased in all athletes at post-RMT (1.24±0.40vs. 1.40±0.50lmin-1 , P=0.12). After 6weeks of no RMT all indices returned towards baseline, with peak work rate (P=0.037), peak oxygen uptake (P=0.041) and end-expiratory lung volume (P<0.034) being significantly lower at follow-up than at post-RMT. There was a significant decrease in left-ventricular end-diastolic volume and stroke volume in response to 45° head-up tilt (P=0.030 and 0.021, respectively); however, all cardiac indices in both supine and tilted positions were unchanged by RMT. Our findings demonstrate the efficacy of RMT with respect to enhancing respiratory muscle strength, lowering exercising lung volumes and increasing exercise capacity. Although the precise mechanisms by which RMT may enhance exercise capacity remain unclear, our data suggest that it is probably not the result of a direct cardiac adaptation associated with RMT.