Inspiratory muscle training reduces sympathetic nervous activity and improves inspiratory muscle weakness and quality of life in patients with chronic heart failure: a clinical trial

The impact of exercise training on muscle sympathetic nerve activity: a systematic review and meta-analysis

The purpose of this systematic review and meta-analysis was to examine the effects of exercise training on muscle sympathetic nerve activity (MSNA) in humans. Studies included exercise interventions [randomized controlled trials (RCTs), nonrandomized controlled trials (non-RCTs), or pre-to-post intervention] that reported on adults (≥18 yr) where MSNA was directly assessed using microneurography, and relevant outcomes were assessed [MSNA (total activity, burst frequency, burst incidence, amplitude), heart rate, blood pressure (systolic blood pressure, diastolic blood pressure, or mean blood pressure), and aerobic capacity (maximal or peak oxygen consumption)]. Forty intervention studies (n = 1,253 individuals) were included. RCTs of exercise compared with no exercise illustrated that those randomized to the exercise intervention had a significant reduction in MSNA burst frequency and incidence compared with controls. This reduction in burst frequency was not different between individuals with cardiovascular disease compared with those without. However, the reduction in burst incidence was greater in those with cardiovascular disease [9 RCTs studies, n = 234, mean difference (MD) -21.08 bursts/100 hbs; 95% confidence interval (CI) -16.51, -25.66; I2 = 63%] compared with those without (6 RCTs, n = 192, MD -10.92 bursts/100 hbs; 95% CI -4.12, -17.73; I2 = 76%). Meta-regression analyses demonstrated a dose-response relationship where individuals with higher burst frequency and incidence preintervention had a greater reduction in values post-intervention. These findings suggest that exercise training reduces muscle sympathetic nerve activity, which may be valuable for improving cardiovascular health.NEW & NOTEWORTHY This systematic review and meta-analysis suggests exercise training reduces muscle sympathetic nerve activity (MSNA), which may be valuable for improving cardiovascular health. The reduction in burst incidence was greater among individuals with cardiovascular disease when compared with those without; exercise training may be particularly beneficial for individuals with cardiovascular disease. Meta-regression analyses demonstrated a dose-response relationship, where individuals with higher sympathetic activity preintervention had greater reductions in sympathetic activity post-intervention.

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

PURPOSE

To identify the clinical effect of inspiratory muscle training (IMT) among esophageal cancer patients undergoing esophagectomy based on randomized controlled trials (RCTs).

METHODS

Several databases were searched for relevant RCTs up to August 23, 2023. Primary outcomes were respiratory muscle function, including the maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP), and pulmonary function, including the forced expiratory volume in one second % (FEV1%), forced vital capacity% (FVC%), maximal ventilator volume (MVV), FEV1/FVC% and FVC. The secondary outcomes were exercise performance, including the six-minute walk distance test (6MWT) and Borg index; mental function and quality of life, as evaluated by the Hospital Anxiety Depression Scale (HADS) and Nottingham Health Profile (NHP) score; and postoperative complications. All the statistical analyses were performed with REVMAN 5.3 software.

RESULTS

Eight RCTs were included in this meta-analysis, with 368 patients receiving IMT and 371 control subjects. The pooled results demonstrated that IMT could significantly enhance respiratory muscle function (MIP: MD = 7.14 cmH2O, P = 0.006; MEP: MD = 8.15 cmH2O, P<0.001) and pulmonary function (FEV1%: MD = 6.15%, P<0.001; FVC%: MD = 4.65%, P<0.001; MVV: MD = 8.66 L, P<0.001; FEV1/FVC%: MD = 5.27%, P = 0.03; FVC: MD = 0.50 L, P<0.001). Furthermore, IMT improved exercise performance (6MWT: MD = 66.99 m, P = 0.02; Borg index: MD = -1.09, P<0.001), mental function and quality of life (HADS anxiety score: MD = -2.26, P<0.001; HADS depression score: MD = -1.34, P<0.001; NHP total score: MD = -48.76, P<0.001). However, IMT did not significantly decrease the incidence of postoperative complications.

CONCLUSION

IMT improves clinical outcomes, such as respiratory muscle function and pulmonary function, in esophageal cancer patients receiving esophagectomy and has potential for broad applications in the clinic.

Effects of high intensity interval-based inspiratory muscle training in patients with heart failure: A single-blind randomized controlled trial

BACKGROUND

Given the promising effects of inspiratory muscle training (IMT), determining the most appropriate IMT protocol will optimize the training benefits.

OBJECTIVES

The objective of this study was to determine the effects of high intensity interval-based inspiratory muscle training (H-IMT) on cardiovascular, pulmonary, physical, and psychosocial functions in patients with heart failure and reduced ejection fraction (HFrEF).

METHODS

Thirty-four patients with HFrEF were randomly assigned to the H-IMT or control group for 3 days/week, 8 weeks training period. The H-IMT group performed IMT at least 70% of the maximal inspiratory pressure, whereas the control group performed unloaded IMT. Each session occurred 7 sets with a total of 21 min consisting of 2-min training and 1-min interval. Heart rate variability (HRV), arterial stiffness, respiratory muscle strength and endurance, diaphragm thickness, quadriceps strength, functional capacity, frailty, dyspnea, fatigue, disease-specific health-related quality of life (HRQoL), and generic HRQoL were evaluated at baseline and after 8 weeks training period by blinded assessors.

RESULTS

Statistically significant between-group differences were observed in the time domain parameters of HRV, arterial stiffness, inspiratory and quadriceps muscle strength, respiratory muscle endurance, diaphragm thickness, functional capacity, frailty, dyspnea, fatigue, and disease-specific HRQoL in favor of the H-IMT group (p<0.05).

CONCLUSIONS

H-IMT is an effective protocol for improving cardiac autonomic function, arterial stiffness, inspiratory and quadriceps muscle strength, respiratory muscle endurance, diaphragm thickness, functional capacity, frailty, dyspnea, fatigue, and disease-specific quality of life in patients with HFrEF.

CLINICAL TRIAL REGISTRATION

NCT04839211.

Effects of inspiratory muscle training on blood pressure- and sleep-related outcomes in patients with obstructive sleep apnea: a meta-analysis of randomized controlled trials

PURPOSE

Obstructive sleep apnea (OSA) is frequently accompanied by hypertension, resulting in cardiovascular comorbidities. Continuous positive airway pressure is a standard therapy for OSA but has poor adherence. Inspiratory muscle training (IMT) may reduce airway collapsibility and sympathetic output, which may decrease OSA severity and blood pressure. In this meta-analysis of randomized controlled trials (RCTs), we evaluated the efficacy of IMT in patients with OSA.

METHODS

We searched PubMed, EMBASE, Cochrane Library, Web of Science, and ClinicalTrials.gov databases for relevant RCTs published before November 2022.

RESULTS

Seven RCTs with a total of 160 patients with OSA were included. Compared with the control group, the IMT group exhibited significantly lower systolic and diastolic blood pressure (mean difference [MD]: - 10.77 and - 4.58 mmHg, respectively), plasma catecholamine levels (MD: - 128.64 pg/mL), Pittsburgh Sleep Quality Index (MD: - 3.06), and Epworth Sleepiness Scale score (MD: - 4.37). No significant between-group differences were observed in the apnea-hypopnea index, forced vital capacity (FVC), ratio of forced expiratory volume in 1 s to FVC, or adverse effects. The data indicate comprehensive evidence regarding the efficacy of IMT for OSA. However, the level of certainty (LOC) remains low.

CONCLUSION

IMT improved blood pressure- and sleep-related outcomes without causing adverse effects and may thus be a reasonable option for lowering blood pressure in patients with OSA. However, additional studies with larger sample sizes and rigorous study designs are warranted to increase the LOC.

Effects of Inspiratory Muscle Training in Patients With Pulmonary Hypertension

The study aimed to examine the effects of inspiratory muscle training (IMT) in patients with pulmonary hypertension (PH). A total of 24 patients with PH were included in the randomized controlled evaluator-blind study. IMT was performed at 40% to 60% of the maximal inspiratory pressure for 30 min/d, 7 d/wk (1 day supervised) for 8 weeks. Respiratory muscle strength, dyspnea, diaphragm thickness (DT), pulmonary functions, 24-hour ambulatory blood pressure (BP), arterial stiffness, exercise capacity, upper extremity functional exercise capacity, physical activity levels, fatigue, anxiety-depression levels, activities of daily living (ADL), and quality of life were evaluated. A total of 24 patients (treatment = 12, control = 12) completed the 8-week follow-up. There was no significant difference between the patient groups in terms of demographic and clinical characteristics (p >0.05). Considering the change between the groups in the treatment and control groups, brachial and central BP, dyspnea, respiratory muscle strength, DT in total lung capacity, knee extension muscle strength, functional exercise capacity, upper extremity functional exercise capacity, physical activity, ADL, fatigue, anxiety, and quality of life improved in favor of the IMT group (p <0.05). In conclusion, IMT has improved brachial and central BP, dyspnea, respiratory muscle strength, DT in total lung capacity, knee extension muscle strength, functional exercise capacity, upper extremity functional exercise capacity, physical activity, ADL, fatigue, anxiety, and quality of life compared with the control group. IMT is an effective method in cardiopulmonary rehabilitation for patients with PH.

Effects of inspiratory muscle training in patients with hypertension: a meta-analysis

Objective

To explore the effects of inspiratory muscle training (IMT) on hypertension and provide guidance for its clinical application as an auxiliary approach.

Methods

Articles published prior to July 2022 were searched in Cochrane Library, Web of Science, PubMed, Embase, CNKI, and Wanfang databases. Included were randomized controlled studies that used IMT to treat individuals with hypertension. The mean difference (MD) was computed using the Revman 5.4 software. In individuals with hypertension, the effects of IMT on systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and pulse pressure (PP) were compared and studied.

Results

There were found to be eight randomized controlled trials totaling 215 patients. According to a meta-analysis, the IMT reduced the SBP (MD: -12.55 mmHg, 95% CI: -15.78, -9.33), DBP (MD: -4.77 mmHg, 95% CI: -6.00, -3.54), HR (MD: -5.92 bpm, 95% CI: -8.72, -3.12), and PP (MD: -8.92 mmHg, 95% CI: -12.08, -5.76) in patients with hypertension. In subgroup analyses, low-intensity IMT showed a better reduction in SBP (MD: -14.47 mmHg, 95% CI: -17.60, -11.34), DBP (MD: -7.70 mmHg, 95% CI: -10.21, -5.18).

Conclusion

IMT may become an auxiliary means to improve the four hemodynamic indexes (SBP, DBP, HR and PP) in patients with hypertension. In subgroup analyses, low-intensity IMT was more effective in regulating blood pressure than medium-high-intensity IMT.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022300908.

Respiratory training in older women: Unravelling central and peripheral hemodynamic slow oscillatory patterns

We hypothesized that inspiratory muscle training (IMT) increases the respiratory-induced low-frequency oscillations of mean blood pressure (MBP) and middle cerebral artery blood velocity (MCAv), upregulating cerebrovascular function in older women. Firstly, participants were recorded with free-breathing (FB) and then breathed at a slow-paced frequency (0.1 Hz; DB test) supported by sonorous metronome feedback. Blood pressure was recorded using finger photoplethysmography method, ECG, and respiration using a thoracic belt. To obtain the MCAv a transcranial ultrasound Doppler device was used. Spectral analysis of MBP, R-R intervals, and mean MCAv time series was obtained by an autoregressive model. The transfer function analysis (TFA) was employed to calculate the coherence, gain, and phase. After that, older women were enrolled in a randomized controlled protocol, the IMT-group (n = 8; 64 ± 3 years-old) performed IMT at 50 % of maximal inspiratory pressure (MIP), and Sham-group, a placebo training at 5 % MIP (Sham-group; n = 6; 66 ± 3 years-old). Participants breathed against an inspiratory resistance twice a day for 4-weeks. DB test is repeated post IMT and Sham interventions. IMT-group, compared to Sham-group, augmented tidal volume responses to DB (Sham-group 1.03 ± 0.41 vs. IMT-group 1.61 ± 0.56 L; p = 0.04), increased respiratory-induced MBP (Sham-group 26.37 ± 4.46 vs. IMT-group 48.21 ± 3.15 mmHg²; p = 0.04) and MCAv (Sham-group 14.16 ± 31.26 vs. IMT-group 79.90 ± 21.76 cm²s^-2; p = 0.03) slow oscillations, and reduced TFA gain (Sham-group 2.46 ± 1.32 vs. IMT-group 1.78 ± 1.30 cm·s^-1.mmHg^-1; p = 0.01). Our findings suggest that IMT increases the respiratory-induced oscillations in MBP and MCAv signals and reduces TFA gain. It seems compatible with an improved dynamic cerebrovascular regulation following IMT in older women.

Inspiratory muscle training in patients with heart failure: A systematic review and meta-analysis

Objective

To explore the effect of inspiratory muscle training (IMT) on patients with heart failure and further explore the impact of IMT on patients with heart failure with preserved ejection fraction.

Methods

PubMed, EMBASE, Cochrane Library, CNKI, Wanfang and VIP databases were systematically searched. Randomized controlled trials of inspiratory muscle training in patients with heart failure were included. Revman 5.3 software was used to calculate the weighted mean difference (MD) of the combined effect size. The effects of IMT on the maximum oxygen uptake (peakVO2), maximum inspiratory pressure (PI_max), ventilation efficiency (V_E/VCO₂), six-minute walking distance (6MWD), forced expiratory volume (FEV₁), forced vital capacity (FVC) and quality of life in patients with heart failure were compared and analyzed.

Results

After systematic retrieval and screening, 17 studies were included in this study, and the quality of the included studies was good. The results showed that IMT could increase peakVO2 (MD 2.53; 95% CI 1. 54, 3. 51; P < 0.0001) and PI_max (MD 17.25; 95% CI 13. 75, 20. 75; P < 0.00001); improve the V_E/VCO₂ (MD −4.22; 95% CI −6.78, −1.66; P = 0.001) and significantly improve the quality of life in patients with heart failure (MD −13.34; 95% CI −20.42, −6.26; P = 0.0002). However, the effect of IMT on 6MWD in patients with heart failure was not statistically significant (MD 74.45; 95% CI −12.88,161.79; P = 0.09), and the effect on lung function (FEV₁ and FVC) was also not statistically significant (P = 0.08; P = 0.86). IMT had a more significant positive effect on peakVO2 (MD 2.98; 95% CI 1.63, 4.34; P < 0.0001) and quality of life (MD −14.52; 95% CI −18.53, −10.52; P < 0.00001) in patients with heart failure with preserved ejection fraction. Descriptive analysis suggested that IMT may positively affect dyspnoea in patients with heart failure. In addition, the choice of evaluation scale may affect the evaluation results of quality of life and dyspnoea.

Conclusion

IMT has a significant positive effect on respiratory status in patients with heart failure, but different dyspnoea and quality of life evaluation scales can affect the final evaluation results.

A comparison of the effects of inspiratory muscle strength and endurance training on exercise capacity, respiratory muscle strength and endurance, and quality of life in pacemaker patients with heart failure: A randomized study

BACKGROUND

Studies have widely investigated the effects of inspiratory muscle strength training in patients with heart failure (HF). The effects of inspiratory muscle strength or endurance training on outcomes in patients with pacemakers have not been adequately studied.

OBJECTIVES

The aim was to compare the effects of inspiratory muscle strength and endurance training on exercise capacity, quality of life (QoL), peripheral and respiratory muscle strength, respiratory muscle endurance, pulmonary function, dyspnea, fatigue, and physical activity levels in pacemaker patients with HF.

METHODS

A randomized, controlled, double-blind study was conducted. Fourteen pacemaker patients with HF received inspiratory muscle strength training (IMST) at 50% of maximal inspiratory pressure (MIP), and 18 patients received endurance training (IMET) at 30% of MIP 7 days/8 weeks. Exercise capacity [6 min. walking test (6MWT) and the Incremental Shuttle Walking Test (ISWT)], pulmonary function, respiratory muscle strength [MIP, maximal expiratory pressure (MEP)], endurance, peripheral muscle strength, dyspnea, fatigue, QoL, and physical activity level were evaluated before and after.

RESULTS

Demographic characteristics were similar in IMST (3F/11M, 56.92 ± 7.61y, EF: 25%, ICD/CRT:11/3) and IMET (4F/14M, 56 ± 10.77y, EF: 30%, ICD/CRT:16/2) groups (p > 0.05). Significant improvements were present in MIP, MEP, respiratory muscle endurance, peripheral muscle strength, 6MWT and ISWT walking distances, dyspnea, QoL, physical activity level, fatigue scores within groups (p ≤ 0.05). However, there were no significant differences between the groups (p > 0.05). There were no significant improvements in FEV₁%, FVC%, FEV₁/FVC%, and FEF_25-75 within and between the groups (p > 0.05).

CONCLUSIONS

Inspiratory muscle strength and endurance training similarly improves respiratory and peripheral muscle strength, exercise capacity, QoL, physical activity level, and decreases dyspnea and fatigue and are safe and effective in pacemaker patients with HF.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov; study number: NCT03501355.

Effects of resistance added on aerobic training on autonomic function in cardiac patients

OBJECTIVE

Autonomic imbalance in patients with chronic heart failure (CHF) and cardiovascular diseases (CVD) is characterized by reduced parasympathetic and enhanced sympathetic activity. Aerobic exercise improves autonomic function in patients with CHF and CVD. However, little is known about the effects of resistance training (RT) on cardiac autonomic function. Therefore, we aimed to investigate the effects of RT added on aerobic training on autonomic function in patients with CHF and CVD.

DATA SOURCES

The relevant clinical trials were searched in PubMed, Physiotherapy evidence Database (PEDro, Science Direct and Google Scholar databases using the following keywords, "resistance or strength training", "chronic heart failure", "coronary artery disease", "myocardial infarction", "hypertension", "cardiovascular disease", "heart rate variability (HRV)", "heart rate recovery (HRR)", "muscle sympathetic nerve activity (MSNA)", and "autonomic function".

DATA SYNTHESIS

Twelve articles with 323 subjects were eligible to be evaluated. The outcome measures included HRV, HRR, and MSNA. There were seven studies on CHF, two on CAD, and three studies on hypertension. Meta-analysis of all the studies showed that combined RT and aerobic training decreased MSNA significantly in patients with CHF and CAD (mean difference: -3.796; CI: -6.779 to 0.813; p=0.013; I2 =93.5%). No study evaluated the effects of RT or combined training on HRR.

CONCLUSION

We could not find sufficient data about the effects of RT alone on HRV and HRR, but the results showed that combined RT and aerobic training improved MSNA in patients with CHF and CAD, significantly. Further studies with similar methodological principles on the same patient population are needed.

Inspiratory muscle weakness in cardiovascular diseases: Implications for cardiac rehabilitation

Exercise limitation is a cardinal manifestation of many cardiovascular diseases (CVD) and is associated with poor prognosis. It is increasingly well understood that exercise-based cardiac rehabilitation (CR) is an intervention that portends favorable clinical outcomes, including improvements in exercise capacity. The etiology of exercise limitation in CVD is multifactorial but is typically governed by terminal sensations of pain, fatigue, and/or breathlessness. A known but perhaps underestimated complication of CVD that contributes to breathlessness and exercise intolerance in such patients is inspiratory muscle dysfunction. For example, inspiratory muscle dysfunction, which encompasses a loss in muscle mass and/or pressure generating capacity, occurs in up to ~40% of patients with chronic heart failure and is associated with breathlessness, exertional intolerance, and worse survival in this patient population. In this review, we define inspiratory muscle weakness, detail its prevalence in a range of CVDs, and discuss how inspiratory weakness impacts physiological function and clinical outcomes in patients with CVD often referred to CR. We also evaluate the available evidence addressing the effects of exercise-based CR with and without concurrent specific inspiratory muscle training (IMT) on inspiratory muscle function, general physiological function, and clinical outcomes in patients with CVD. Finally, we consider whether the assessment of global respiratory muscle function should become standard as part of the patient intake assessment for phase II CR programs, giving practical guidance on the implementation of such measures as well as IMT as part of phase II CR.

Time-efficient, high-resistance inspiratory muscle strength training for cardiovascular aging

Cardiovascular diseases (CVD) remain the leading cause of death in developed and developing societies and aging is the primary risk factor for CVD. Much of the increased risk of CVD in midlife/older adults (i.e., adults aged 50 years and older) is due to increases in blood pressure, vascular endothelial dysfunction and stiffening of the large elastic arteries. Aerobic exercise training is an effective lifestyle intervention to improve CV function and decrease CVD risk with aging. However, <40% of midlife/older adults meet guidelines for aerobic exercise, due to time availability-related barriers and other obstacles to adherence. Therefore, there is a need for new lifestyle interventions that not only improve CV function with aging but also promote adherence. High-resistance inspiratory muscle strength training (IMST) is an emerging, time-efficient (5 min/day) lifestyle intervention. Early research suggests high-resistance IMST may promote adherence, lower blood pressure and potentially improve vascular endothelial function. However, additional investigation will be required to more definitively establish high-resistance IMST as a healthy lifestyle intervention for CV aging. This review will summarize the current evidence on high-resistance IMST for improving CV function with aging and will identify key research gaps and future directions.

Effects of inspiratory muscle training combined with aerobic exercise training on neurovascular control in chronic heart failure patients

Aims

We tested the hypothesis that the effects of combined inspiratory muscle training and aerobic exercise training (IMT + AET) on muscle sympathetic nerve activity (MSNA) and forearm blood flow in patients with heart failure with reduced ejection fraction are more pronounced than the effects of AET alone.

Methods and results

Patients aged 30–70 years, New York Heart Association Functional Class II‐III, and left ventricular ejection fraction ≤40% were randomly assigned to four groups: IMT (n = 11), AET (n = 12), IMT + AET (n = 9), and non‐training (NT; n = 10). MSNA was recorded using microneurography. Forearm blood flow was measured by venous occlusion plethysmography and inspiratory muscle strength by maximal inspiratory pressure. IMT consisted of 30 min sessions, five times a week, for 4 months. Moderate AET consisted of 60 min sessions, three times a week for 4 months. AET (−10 ± 2 bursts/min, P = 0.03) and IMT + AET (−13 ± 4 bursts/min, P = 0.007) reduced MSNA. These responses in MSNA were not different between AET and IMT + AET groups. IMT (0.22 ± 0.08 mL/min/100 mL, P = 0.03), AET (0.27 ± 0.09 mL/min/100 mL, P = 0.01), and IMT + AET (0.35 ± 0.12 mL/min/100 mL, P = 0.008) increased forearm blood flow. No differences were found between groups. AET (3 ± 1 mL/kg/min, P = 0.006) and IMT + AET (4 ± 1 mL/kg/min, P = 0.001) increased peak oxygen consumption. These responses were similar between these groups. IMT (20 ± 3 cmH₂O, P = 0.005) and IMT + AET (18 ± 3 cmH₂O, P = 0.01) increased maximal inspiratory pressure. No significant changes were observed in the NT group.

Conclusions

IMT + AET causes no additive effects on neurovascular control in patients with heart failure with reduced ejection fraction compared with AET alone. These findings may be, in part, because few patients had inspiratory muscle weakness.

Inspiratory muscle training improves breathing pattern and sympatho-vagal balance but not spontaneous baroreflex sensitivity in older women

Even though recent studies reported a positive inspiratory muscle training (IMT) effect on cardiovascular autonomic modulation, its underlying mechanisms as the breathing pattern remain unclear. The study aimed to investigate the IMT effects on resting heart rate variability (HRV), spontaneous baroreflex sensitivity (BRS), and spontaneous breathing pattern in older women. Fourteen healthy older women participated in this study, allocated in IMT (50 % MIP; n = 8) or Sham (5% MIP; n = 6) protocols for four weeks. Blood pressure, heart rate, and ventilatory data were continuously recorded before and after interventions. After four weeks, IMT-group increased maximal inspiratory pressure and vagal-mediated HRV, following by the reduction of sympatho-mediated HRV and the inspiratory time during the spontaneous breathing cycle compared to Sham-group, but did not change BRS. Therefore, the shorter inspiratory time suggests a putative mechanism behind improved vagal-mediated HRV post-IMT in older women.

Time-dependent effects of inspiratory muscle training and detraining on cardiac autonomic control in older women

Inspiratory muscle training improved maximal inspiratory pressure (MIP) and vagal-mediated heart rate variability (HRV) in older women. However, it is unknown what occurs if the training is discontinued (detraining protocol). The aim of this study was to investigate the IMT and detraining effects on resting HRV in older women. Twelve healthy older women (60-72 yrs) enrolled in home-based IMT at 50% MIP (IMT-group) or placebo at 5% MIP (Sham-group) protocol for 4 weeks using a mechanical pressure threshold loading device. The participants were not engaged in any other exercise protocol at that time. During IMT and Sham interventions, the inspiratory load was adjusted weekly by the actual MIP and resting heart rate variability (HRV) evaluated. After training cessation (4 weeks of detraining), participants returned to the lab for HRV and MIP recordings. Adherence to IMT was superior to 95%. IMT increased MIP (23 ± 8 cmH₂O) and vagal-mediated HRV (normalized HF; 37 ± 8%), following by the reduction of sympatho-vagal balance (LF/HF), from the second week to the end of the protocol compared to sham-group. After detraining, IMT-group reduced MIP (-23 ± 8 cmH₂O) and vagal-mediated HRV (normalized HF; -38 ± 14%) returning to baseline values. In conclusion, MIP and vagal-HRV improvements induced by IMT were reversed by four weeks of detraining.

Effect of inspiratory muscle training on respiratory muscle strength and functional capacity in patients with type 2 diabetes mellitus: A randomized clinical trial

BACKGROUND

Type 2 diabetes mellitus (T2DM) is usually associated with respiratory manifestations including inspiratory muscle weakness which affects exercise capacity. The present study aimed to determine the effect of inspiratory muscle training (IMT) on inspiratory muscle strength and exercise capacity in patients with Type 2 diabetes mellitus (T2DM).

METHODS

This was a randomized controlled trial in patients with type 2 diabetes mellitus with no previous cardiopulmonary or neuromuscular diseases. Patients had no back pain. Patients were randomized into interventional or placebo groups. Sniff nasal inspiratory pressure (SNIP), maximum inspiratory pressure (MIP), and six-minute walking test (6MWT) were measured at baseline and 8 weeks post incremental inspiratory muscle training.

RESULTS

At baseline, interventional and placebo groups were similar in age, body mass index, sex inspiratory muscle strength, and exercise capacity. After 8 weeks of incremental inspiratory muscle training at 40% of MIP, the interventional group had a significant increase in the SNIP (mean difference: 18.5 ± 5.30 cm H2O vs 2.8 ± 4.8 cm H2O) and MIP (mean difference: 19.4 ± 4.3 Vs 5.4 ± 3.6 cm H2O) compared to the placebo group, respectively. The interventional group showed improvement in the 6MWT (mean difference: 70 ± 29 m vs 34 ± 24 m) compared to the placebo group, P < .05.

CONCLUSION

Incremental inspiratory muscle training increased the diaphragm strength in patients with T2DM and improved exercise capacity.

Acute cardiovascular responses to a single bout of high intensity inspiratory muscle strength training in healthy young adults

High intensity, low volume inspiratory muscle strength training (IMST) has favorable effects on casual systolic blood pressure and systemic vascular resistance. However, the acute effects of IMST on heart rate (HR), blood pressure (BP), and sympathetic regulation of vascular resistance and the trajectory of post exercise recovery are not known. We recruited 14 young adults (7 women/7 men, age: 22 ± 2 years) to perform a single bout of high intensity IMST (inspiratory resistance set at 75% of maximal inspiratory pressure) importantly, female and male subjects were matched in regard to the target inspiratory pressure and target inspiratory muscle work per breath. We recorded HR, beat-to-beat changes in BP and postganglionic, muscle sympathetic nerve activities (MSNA) continuously throughout baseline, a single bout of IMST (comprising five sets of 6 inspiratory efforts) and in recovery. We show that one bout of IMST does not effect a change in BP, however, it effects a significant increase in HR (68.4 ± 11.7 beats/min versus 85.4 ± 13.6 beats/min; P < 0.001) and a significant decline in MSNA (6.8 ± 1.1 bursts/15 s bin; P < 0.001 versus 3.6 ± 0.6 bursts/15 s bin) relative to baseline. Remarkably, among men MSNA rebounded to baseline levels within the first minute of recovery, however, in women, MSNA suppression persisted for 5 min. We show that in healthy young adults, high intensity, low volume respiratory training results in the acute suppression of MSNA. Importantly, MSNA suppression is of greater magnitude and longer duration in women than in men.NEW & NOTEWORTHY Previous studies show 6 weeks of high intensity, low volume inspiratory muscle strength training (IMST) lowers blood pressure (BP) and systemic vascular resistance in young adults. However, the acute response to IMST is unknown. We characterized BP, heart rate, and sympathetic nervous activity (SNA) in healthy young adults at baseline, during IMST, and in recovery. There was no acute effect of IMST on BP, however, there was significant IMST-related suppression of SNA that was of greater magnitude in women than men.

Unraveling the Role of Respiratory Muscle Metaboloreceptors under Inspiratory Training in Patients with Heart Failure

Exercise intolerance may be considered a hallmark in patients who suffer from heart failure (HF) syndrome. Currently, there is enough scientific evidence regarding functional and structural deterioration of skeletal musculature in these patients. It is worth noting that muscle weakness appears first in the respiratory muscles and then in the musculature of the limbs, which may be considered one of the main causes of exercise intolerance. Functional deterioration and associated atrophy of these respiratory muscles are related to an increased muscle metaboreflex leading to sympathetic–adrenal system hyperactivity and increased pulmonary ventilation. This issue contributes to increased dyspnea and/or fatigue and decreased aerobic function. Consequently, respiratory muscle weakness produces exercise limitations in these patients. In the present review, the key role that respiratory muscle metaboloreceptors play in exercise intolerance is accurately addressed in patients who suffer from HF. In conclusion, currently available scientific evidence seems to affirm that excessive metaboreflex activity of respiratory musculature under HF is the main cause of exercise intolerance and sympathetic–adrenal system hyperactivity. Inspiratory muscle training seems to be a useful personalized medicine intervention to reduce respiratory muscle metaboreflex in order to increase patients’ exercise tolerance under HF condition.

Obesity as an additional factor for autonomic imbalance and poor sleep behavior in chronic obstructive pulmonary disease: a case-control study

OBJECTIVES

We compared the autonomic modulation and sleep behavior of eutrophic and overweight patients with chronic obstructive pulmonary disease (COPD).

METHODS

COPD participants were divided into the overweight and eutrophic groups. Pulmonary function, blood pressure, body composition, autonomic modulation, and the Pittsburgh Sleep Quality Index score were assessed. Participants performed the six-minute walk test for functional assessment.

RESULTS

Spirometric variables obtained in eutrophic and overweight individuals with COPD showed no statistically different results. We observed that the SDNN index indicated lower overall variability (p=0.003), and root mean square of successive differences between normal heart beats (RMSSD) (p=0.04) indicated lower parasympathetic modulation in the overweight group than observed in the eutrophic group. The indexes of the frequency domain presented lower values of total variability (p<0.01), low frequency bands (p<0.01), and high frequency (p=0.02), suggesting a higher sympathetic modulation and reduced parasympathetic modulation of the overweight group compared to eutrophic group. The overweight group also showed reduced sleep quality than the eutrophic group.

CONCLUSION

Overweight COPD patients showed lower autonomic modulation and impaired sleep quality, latency, and efficiency as compared eutrophic subjects. These results reinforce the importance of weight control and the acquisition of healthy habits in this population.

Acute Effects of Resistance Exercise With Blood Flow Restriction in Elderly Women: A Pilot Study

AIM

To compare the acute effects of two resistance exercise sessions with different partial blood flow restrictions (BFR) on hemodynamic parameters and cardiac autonomic modulation in older women with metabolic syndrome.

METHODS

Thirty-nine older women (64.4 ± 4.5 years) were allocated into three groups: BFR0 = resistance exercise (20%, 1 maximum repetition [MR]) + 0% BFR; BFR60 = 20% 1 MR resistance exercise + 60% BFR; and BFR80 = 20% 1MR resistance exercise + 80% BFR.

RESULTS

A reduction of 14 mmHg (BFR60 group) and 13 mmHg (BRF80 group) was observed 48 hr after the first exercise session, while vagal modulation was increased in the BRF60 group after 24 and 48 hr.

CONCLUSION

A low-intensity resistance exercise session with 60% and 80% of BFR resulted in blood pressure (systolic, diastolic, and mean) reduction and positive changes on heart rate variability after 24 h of a RE session.

Inspiratory Muscle Training in Patients With Heart Failure: What Is New? Systematic Review and Meta-Analysis

OBJECTIVE

The benefits of inspiratory muscle training (IMT) have already been demonstrated in patients with heart failure (HF), but the best mode of training and which patients benefit from this intervention are not clear. The purpose of this study was to review the effects of IMT on respiratory muscle strength, functional capacity, pulmonary function, quality of life, and dyspnea in patients with HF; IMT isolated or combined with another intervention (combined IMT), the presence of inspiratory muscle weakness, training load, and intervention time were considered.

METHODS

The search included the databases MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Physiotherapy Evidence Database, and LILACS database through September 2019. The review included randomized studies that assessed IMT in isolation or combined with another intervention-in comparison with a control group, a placebo, or another intervention-in patients with HF. Fourteen studies were included, 13 for meta-analysis (10 for isolated IMT and 3 for combined IMT).

RESULTS

Isolated IMT demonstrated an increase in maximal inspiratory pressure (MIP) (25.12 cm H2O; 95% CI = 15.29 - 34.95), 6-Minute Walk Test (81.18 m; 95% CI = 9.73 - 152.63), maximum oxygen consumption (12 weeks: 3.75 mL/kg/min; 95% CI = 2.98 to 4.51), and quality of life (-20.68; 95% CI = -29.03 to -12.32). The presence of inspiratory muscle weakness, higher loads, and longer intervention times resulted in greater increases in MIP. IMT combined with another intervention demonstrated an increase only in MIP.

CONCLUSIONS

Isolated IMT resulted in an increase in inspiratory muscle strength, functional capacity, and quality of life. IMT combined with another intervention resulted only in a small increase in inspiratory strength. Isolated IMT with higher loads can be considered an adjuvant intervention, especially for those who do not adhere to conventional rehabilitation and who have respiratory muscle weakness.

IMPACT

A systematic review was necessary to review the effects of IMT on respiratory muscle strength, lung function, functional capacity, quality of life, and dyspnea in patients with HF. Various clinical issues important for a better training prescription were considered; these included whether the performance of the training IMT as a form of isolated training benefits patients with HF, whether the combination of IMT with another intervention has additional effects, whether any patient with HF can benefit from IMT (alone or combined with another intervention), and whether only patients who already have respiratory muscle weakness benefit. Also important was establishing which training load provides the best result and the best intervention time, so that health care can be provided more efficiently.

LAY SUMMARY

For people with heart failure, IMT by itself, without being combined with other exercise, can improve ease of breathing, increase the amount of distance that they can walk, and improve quality of life. Inspiratory training with higher loads might be helpful for those with respiratory muscle weakness who are unable to do conventional exercise.

Combined aerobic/resistance/inspiratory muscle training as the 'optimum' exercise programme for patients with chronic heart failure: ARISTOS-HF randomized clinical trial

AIMS

An 'optimum' universally agreed exercise programme for heart failure (HF) patients has not been found. ARISTOS-HF randomized clinical trial evaluates whether combined aerobic training (AT)/resistance training (RT)/inspiratory muscle training (IMT) (ARIS) is superior to AT/RT, AT/IMT or AT in improving aerobic capacity, left ventricular dimensions, and secondary functional outcomes.

METHODS AND RESULTS

Eighty-eight patients of New York Heart Association II-III, left ventricular ejection fraction  ≤ 35% were randomized to an ARIS, AT/RT, AT/IMT, or AT group, exercising 3 times/week, 180 min/week for 12 weeks. Pre- and post-training, peakVO2 was evaluated with cardiopulmonary exercise testing, left ventricular dimensions using echocardiography, walking distance with the 6-min walk test (6MWT), quality of life by the Minnesota Living with HF Questionnaire (MLwHFQ), while a programme preference survey (PPS) was used. Seventy-four patients of [mean 95% (confidence interval, CI)] age 66.1 (64.3-67.9) years and peakVO2 17.3 (16.4-18.2) mL/kg/min were finally analysed. Between-group analysis showed a trend for increased peakVO2 (mL/kg/min) [mean contrasts (95% CI)] in the ARIS group [ARIS vs. AT/RT 1.71 (0.163-3.25)(.), vs. AT/IMT 1.50 (0.0152-2.99)(.), vs. AT 1.38 (-0.142 to 2.9)(.)], additional benefits in circulatory power (mL/kg/min⋅mmHg) [ARIS vs. AT/RT 376 (60.7-690)*, vs. AT/IMT 423 (121-725)*, vs. AT 345 (35.4-656)*], left ventricular end-systolic diameter (mm) [ARIS vs. AT/RT -2.11 (-3.65 to (-0.561))*, vs. AT -2.47 (-4.01 to (-0.929))**], 6MWT (m) [ARIS vs. AT/IMT 45.6 (18.3-72.9)**, vs. AT 55.2 (27.6-82.7)****], MLwHFQ [ARIS vs. AT/RT -7.79 (-11 to (-4.62))****, vs. AT -8.96 (-12.1 to (-5.84))****], and in PPS score [mean (95% CI)] [ARIS, 4.8 (4.7-5) vs. AT, 4.4 (4.2-4.7)*] [(.) P ≤ 0.1; *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; ****P ≤ 0.0001].

CONCLUSION

ARISTOS-HF trial recommends exercise training for 180 min/week and supports the prescription of the ARIS training regime for HF patients (Clinical Trial Registration: http://www.clinicaltrials.gov. ARISTOS-HF Clinical Trial number, NCT03013270).

Effects of incentive spirometry on cardiopulmonary parameters, functional capacity and glycemic control in patients with Type 2 diabetes

BACKGROUND

Patients with Type 2 diabetes mellitus (T2DM) suffer cardiopulmonary impairment and may present with weakness of the inspiratory muscles.

OBJECTIVE

This study was designed to determine the effects of incentive spirometry (IS) on selected cardiopulmonary parameters, functional capacity and glycemic control in patients with T2DM.

METHODS

Fifty-nine participants (25 males and 34 females) recruited from the out-patient clinic of the Department of Medicine of two hospitals in Lagos State, Nigeria, who were randomly assigned into two groups, completed the study. In addition to the medical management of T2DM, IS group received incentive spirometry while control group continued with the medical management of T2DM alone. Selected cardiovascular parameters, pulmonary parameters, functional capacity (using 6-min walk test) and fasting blood glucose level were assessed at baseline and at the end of eight weeks intervention period. Data were analyzed using the Statistical Package for Social Sciences (SPSS Version 21). Level of significance was set at p < 0 . 05 .

RESULTS

There were statistically significant improvements in all the cardiovascular parameters ( p = 0 . 001 ) of IS group except systolic blood pressure. There were significant changes in all the pulmonary parameters, functional capacity and glycemic control ( p < 0 . 05 ) of IS group while there was none in control group. There were significant differences between the mean changes of various selected outcome measures of the two groups ( p < 0 . 05 ) except for diastolic blood pressure and blood glucose level.

CONCLUSION

IS had positive effects in improving cardiopulmonary function, functional capacity and glycemic control in patients with T2DM.

Sympathetic neural overdrive in congestive heart failure and its correlates: systematic reviews and meta-analysis

BACKGROUND AND OBJECTIVES

Sympathetic neural activation occurs in congestive heart failure (CHF). However, the small sample size of the microneurographic studies, heterogeneity of the patients examined, presence of comorbidities as well as confounders (including treatment) represented major weaknesses not allowing to identify the major features of the phoenomenon, particularly in mild CHF. This meta-analysis evaluated 2530 heart failure (CHF) patients recruited in 106 microneurographic studies. It was based on muscle sympathetic nerve activity (MSNA) quantification in CHF of different clinical severity, but data from less widely addressed conditions, such as ischemic vs. idiopathic, were also considered.

METHODS

Assessment was extended to the relationships of MSNA with venous plasma norepinephrine, heart rate (HR) and echocardiographic parameters of cardiac morphology [left ventricular (LV) end-diastolic diameter] and function (LV ejection fraction) as well.

RESULTS

MSNA was significantly greater (1.9 times, P < 0.001) in CHF patients as compared with healthy controls, a progressive significant increase being observed from New York Heart Association classes I-IV in unadjusted and adjusted analyses. MSNA was significantly greater in both untreated and treated CHF (P < 0.001 for both), related to left ventricular (LV) end-diastolic diameter and to a lesser extent to LV ejection fraction (r = 0.24 and -0.05, P < 0.001 and <0.01, respectively), and closely associated with HR (r = 0.66, P < 0.001) and plasma norepinephrine (r = 0.68, P < 0.001).

CONCLUSION

CHF is characterized by sympathetic overactivity which mirrors the degree of LV dysfunction independently of the stage of CHF, its cause and presence of confounders or pharmacological treatment. plasma norepinephrine and HR represent potentially valuable surrogate markers of sympathetic activation in the clinical setting.

Functional Infrared Thermal Imaging: A Contemporary Tool in Soft Tissue Screening

Soft tissue injury screening faces two main diagnostic challenges. One is the perceptual bias of the athlete in terms of referred pain and second injury assessment tools are not only in need of highly specialized personal but they are also financially demanding. Since ankle sprains is one of the leading soft tissue injuries, the current study was set to examine the suitability of functional infrared thermal imaging (fITI) in evaluating physiological alteration on the ankle as a result of exercise or injury. The current study consists of a case report of a patient with an ankle sprain and the behavior of temperature after a series of physiotherapy sessions. Moreover to strengthen the communication of the report, results from a healthy population sample were added to draw a deeper understanding on physiological temperature manifestations on soft tissue. Twenty participants underwent a 30-minute treadmill run with pictures of their ankles being taken during rest and after exercise. In addition the case of a patient is reported that has suffered an ankle sprain followed for a period of over a month. It was observed that the temperature of the ankles of participants that underwent physical exercise rose on average by 2.4 °C after taking into account both the medial and lateral sides of the both ankles. In addition the patient's left ankle appeared to be 2.5 °C above the temperature of the non-affected right ankle. This phenomenon of unilateral hyperthermia of the left injured side seems to start to dissipate by the 21st day following the injury, completely resolving by the 42nd day achieving bilateral isothermia in both ankles. Thermal imaging provides a reliable tool for the screening of soft tissue strain and injury. The current study further expands the literature on soft tissue screening with the use of thermal imaging, adding a quantifiable way for assessing the extend of tissue damage. The implemented method of analyses offers a suggested simple way not only in visualizing trauma but also physical strain. Nevertheless further investigations with a variety in the severity of ankle sprains need to be applied in order for thermal imaging to be used as a first line tool for the assessment and recovery of ankle sprains.

Inspiratory Muscle Training in Patients with Heart Failure

Background: Prior systematic reviews and meta-analysis addressed that inspiratory muscle training (IMT) improved inspiratory muscle weakness, cardiorespiratory fitness and quality of life similar to conventional exercise training as a first alternative in deconditioned patients with heart failure (HF) lead to a better adaptation to posterior exercise training. The heterogeneity and variability in a wide range of new studies about this topic led to the necessity of an updated and comprehensive narrative review. The present review aimed to analyze and update the most relevant studies about IMT in patients who suffer from HF. Methods: A narrative review was carried out about IMT in HF patients including 26 experimental studies divided into 21 clinical trials and 5 quasi-experimental studies identified through database searching in PubMed, Cochrane and PEDro. Results: There is enough evidence to state that IMT produces improvements in functional capacity of patients with HF. Nevertheless, there is not enough evidence to support that IMT could improve cardiovascular parameters, blood biomarkers or quality of life in these patients. Conclusions: Thus, IMT may be recommended to improve functional capacity in patients who suffer from HF; nevertheless, more evidence is needed regarding cardiovascular parameters, biomarkers and quality of life. Furthermore, mortality or HF hospitalization was not evaluated and most studies were not longer than 3 months. According to IMT protocols and study designs heterogeneity and mid-term follow-up, further investigations through high-quality long-term randomized clinical trials should be performed to achieve systematic reviews and meta-analysis to support strong evidence for IMT in HF patients.

Effects of aerobic and inspiratory training on skeletal muscle microRNA-1 and downstream-associated pathways in patients with heart failure

BACKGROUND

The exercise intolerance in chronic heart failure with reduced ejection fraction (HFrEF) is mostly attributed to alterations in skeletal muscle. However, the mechanisms underlying the skeletal myopathy in patients with HFrEF are not completely understood. We hypothesized that (i) aerobic exercise training (AET) and inspiratory muscle training (IMT) would change skeletal muscle microRNA-1 expression and downstream-associated pathways in patients with HFrEF and (ii) AET and IMT would increase leg blood flow (LBF), functional capacity, and quality of life in these patients.

METHODS

Patients age 35 to 70 years, left ventricular ejection fraction (LVEF) ≤40%, New York Heart Association functional classes II-III, were randomized into control, IMT, and AET groups. Skeletal muscle changes were examined by vastus lateralis biopsy. LBF was measured by venous occlusion plethysmography, functional capacity by cardiopulmonary exercise test, and quality of life by Minnesota Living with Heart Failure Questionnaire. All patients were evaluated at baseline and after 4 months.

RESULTS

Thirty-three patients finished the study protocol: control (n = 10; LVEF = 25 ± 1%; six males), IMT (n = 11; LVEF = 31 ± 2%; three males), and AET (n = 12; LVEF = 26 ± 2%; seven males). AET, but not IMT, increased the expression of microRNA-1 (P = 0.02; percent changes = 53 ± 17%), decreased the expression of PTEN (P = 0.003; percent changes = -15 ± 0.03%), and tended to increase the p-AKT^ser473 /AKT ratio (P = 0.06). In addition, AET decreased HDAC4 expression (P = 0.03; percent changes = -40 ± 19%) and upregulated follistatin (P = 0.01; percent changes = 174 ± 58%), MEF2C (P = 0.05; percent changes = 34 ± 15%), and MyoD expression (P = 0.05; percent changes = 47 ± 18%). AET also increased muscle cross-sectional area (P = 0.01). AET and IMT increased LBF, functional capacity, and quality of life. Further analyses showed a significant correlation between percent changes in microRNA-1 and percent changes in follistatin mRNA (P = 0.001, rho = 0.58) and between percent changes in follistatin mRNA and percent changes in peak VO₂ (P = 0.004, rho = 0.51).

CONCLUSIONS

AET upregulates microRNA-1 levels and decreases the protein expression of PTEN, which reduces the inhibitory action on the PI3K-AKT pathway that regulates the skeletal muscle tropism. The increased levels of microRNA-1 also decreased HDAC4 and increased MEF2c, MyoD, and follistatin expression, improving skeletal muscle regeneration. These changes associated with the increase in muscle cross-sectional area and LBF contribute to the attenuation in skeletal myopathy, and the improvement in functional capacity and quality of life in patients with HFrEF. IMT caused no changes in microRNA-1 and in the downstream-associated pathway. The increased functional capacity provoked by IMT seems to be associated with amelioration in the respiratory function instead of changes in skeletal muscle. ClinicalTrials.gov (Identifier: NCT01747395).

Time-efficient physical training for enhancing cardiovascular function in midlife and older adults: promise and current research gaps

Cardiovascular diseases (CVD) remain the leading cause of death in developed societies, and "midlife" (50-64 yr) and older (65+) men and women bear the great majority of the burden of CVD. Much of the increased risk of CVD in this population is attributable to CV dysfunction, including adverse changes in the structure and function of the heart, increased systolic blood pressure, and arterial dysfunction. The latter is characterized by increased arterial stiffness and vascular endothelial dysfunction. Conventional aerobic exercise training, as generally recommended in public health guidelines, is an effective strategy to preserve or improve CV function with aging. However, <40% of midlife and older adults meet aerobic exercise guidelines, due in part to time availability-related barriers. As such, there is a need to develop evidence-based time-efficient exercise interventions that promote adherence and optimize CV function in these groups. Two promising interventions that may meet these criteria are interval training and inspiratory muscle strength training (IMST). Limited research suggests these modes of training may improve CV function with time commitments of ≤60 min/wk. This review will summarize the current evidence for interval training and IMST to improve CV function in midlife/older adults and identify key research gaps and future directions.

Effects of inspiratory muscle-training intensity on cardiovascular control in amateur cyclists

Chronic effects of inspiratory muscle training (IMT) on autonomic function and baroreflex regulation are poorly studied. This study aims at evaluating chronic effects of different IMT intensities on cardiovascular control in amateur cyclists. A longitudinal, randomized, controlled blind study was performed on 30 recreational male cyclists undergoing IMT for 11 wk. Participants were randomly allocated into sham-trained group (SHAM, n = 9), trained group at 60% of the maximal inspiratory pressure (MIP60, n = 10), and trained group at critical inspiratory pressure (CIP, n = 11). Electrocardiogram, finger arterial pressure, and respiratory movements were recorded before (PRE) and after (POST) training at rest in supine position (REST) and during active standing (STAND). From the beat-to-beat series of heart period (HP) and systolic arterial pressure (SAP), we computed time domain markers, frequency domain indexes in the low frequency (0.04-0.15 Hz) and high frequency (HF, 0.15-0.4 Hz) bands, an entropy-based complexity index (CI), and baroreflex markers estimated from spontaneous HP-SAP sequences. Compared with SHAM, the positive effect of MIP60 over the HP series led to the HF power increase during REST (PRE: 521.2 ± 447.5 ms²; POST: 1,161 ± 878.9 ms²) and the CI rise during STAND (PRE: 0.82 ± 0.18; POST: 0.97 ± 0.13). Conversely, the negative effect of CIP took the form of the decreased HP mean during STAND (PRE: 791 ± 71 ms; POST: 737 ± 95 ms). No effect of IMT was visible over SAP and baroreflex markers. These findings suggest that moderate-intensity IMT might be beneficial when the goal is to limit cardiac sympathetic hyperactivity at REST and/or in response to STAND.

Respiratory training interventions improve health status of heart failure patients: A systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

Prior studies indicate that doing breathing exercises improves physical performance and quality of life (QoL) in heart failure patients. However, these effects remain unclear and contradictory.

AIM

To determine the effects of machine-assisted and non-machine-assisted respiratory training on physical performance and QoL in heart failure patients.

METHODS

This was a systematic review and network meta-analysis study. A literature search of electronic databases was conducted for randomized controlled trials (RCTs) on heart failure. Respiratory training interventions were grouped as seven categories: IMT_Pn (inspiratory muscle training without pressure or < 10% maximal inspiratory pressure, MIP), IMT_Pl (inspiratory muscle training with low pressure, 10%-15% MIP), IMT_Pm (inspiratory muscle training with medium pressure, 30%-40% MIP), IMT_Ph (inspiratory muscle training with high pressure, 60% MIP or MIP plus aerobics), Aerobics (aerobic exercise or weight training), Qi_Ex (tai chi, yoga, and breathing exercise), and none. The four outcomes were heart rate, peak oxygen uptake (VO₂ peak), 6-min walking distance test (6MWT), and Minnesota Living with Heart Failure QoL. The random-effects model, side-splitting model, and the surface under the cumulative ranking curve (SUCRA) were used to test and analyze the data.

RESULTS

A total of 1499 subjects from 31 RCT studies were included. IMT_Ph had the highest effect sizes for VO₂ peak and 6MWT, IMT_Pm highest for QoL, and Qi_Ex highest for heart rate. Aerobics had the second highest for VO₂ peak, Qi_Ex second highest for 6MWT, and IMT_Ph second highest for heart rate and QoL.

CONCLUSION

This study supports that high- and medium-intensity machine-assisted training improves exercise capacity and QoL in hospital-based heart failure patients. After hospital discharge, non-machine-assisted training continuously improves cardiac function.

Can Inspiratory Muscle Training Improve Exercise Tolerance and Lower Limb Function After Myocardial Infarction?

Background

Respiratory therapy is an integral part of treatment of cardiac patients. The aim of this study was to evaluate the effect of addition of inspiratory muscle training (IMT) to second-stage cardiac rehabilitation on exercise tolerance and function of lower extremities in patients following myocardial infarction (MI).

Material/Methods

This study included 90 patients (mean age 65 years) with MI who took part in the second stage of an 8-week cycle of cardiac rehabilitation (CR). They were divided into 3 groups: group I underwent CR and IMT, group II only underwent CR, and group III only underwent IMT. Groups I and II were allocated randomly according sealed opaque envelopes. The third group consisted of patients who could not participate in standard rehabilitation for various reasons. Before and after the 8-week program, participants were assessed for maximal inspiratory and expiratory pressure (PImax and PEmax) values, exercise tolerance, and knee muscle strength.

Results

In groups I and II, a significant increase in the PImax parameters and exercise tolerance parameters (MET) were observed. Group I had increased PEmax parameters. In group III, the same changes in the parameter values that reflect respiratory muscle function were observed. All of the examined strength parameters of the knee joint muscles demonstrated improvement in all of the investigated groups, but the biggest differences were observed in group I.

Conclusions

Use of IMT in the ambulatory rehabilitation program of MI patients resulted in improved rehabilitation efficacy, leading to a significant improvement in physical condition.

Home-based inspiratory muscle training for management of older patients with heart failure with preserved ejection fraction: does baseline inspiratory muscle pressure matter?

BACKGROUND

Heart failure with preserved ejection fraction is a clinical syndrome characterised by reduced exercise capacity. Some evidence has shown that a simple and home-based programme of inspiratory muscle training offers promising results in terms of aerobic capacity improvement in patients with heart failure with preserved ejection fraction. This study aimed to investigate whether the baseline inspiratory muscle function predicts the changes in aerobic capacity (measured as peak oxygen uptake; peak VO₂) after a 12-week home-based programme of inspiratory muscle training in patients with heart failure with preserved ejection fraction.

METHODS

A total of 45 stable symptomatic patients with heart failure with preserved ejection fraction and New York Heart Association II-III received a 12-week home-based programme of inspiratory muscle training between June 2015 and December 2016. They underwent cardiopulmonary exercise testing and measurements of maximum inspiratory pressure pre and post-inspiratory muscle training. Maximum inspiratory pressure and peak VO₂ were registered in both visits. Multivariate linear regression analysis was used to assess the association between changes in peak VO₂ (Δ-peakVO₂) and baseline predicted maximum inspiratory pressure (pp-MIP).

RESULTS

The median (interquartile range) age was 73 (68-77) years, 47% were women and 35.6% displayed New York Heart Association III. The mean peak VO₂ at baseline and Δ-peakVO₂ post-training were 10.4±2.8 ml/min/kg and +2.2±1.3 ml/min/kg (+21.3%), respectively. The median (interquartile range) of pp-MIP and Δ-MIP were 71% (64-92) and 39.2 (26.7-80.4) cmH₂O, respectively. After a multivariate analysis, baseline pp-MIP was not associated with Δ-peakVO₂ (β coefficient 0.005, 95% confidence interval -0.009-0.019, P=0.452).

CONCLUSIONS

In symptomatic and deconditioned older patients with heart failure with preserved ejection fraction, a home-based inspiratory muscle training programme improves aerobic capacity regardless of the baseline maximum inspiratory pressure.

Current insights of inspiratory muscle training on the cardiovascular system: a systematic review with meta-analysis

Background: Cardiorespiratory limitation is a common hallmark of cardiovascular disease which is a key component of pharmacological and exercise treatments. More recently, inspiratory muscle training (IMT) is becoming an effective complementary treatment with positive effects on muscle strength and exercise capacity. We assessed the effectiveness of IMT on the cardiovascular system through autonomic function modulation via heart rate variability and arterial blood pressure.

Methods: Randomized controlled trials (RCTs) were identified from searches of The Cochrane Library, MEDLINE and EMBASE to November 2018. Citations, conference proceedings and previous reviews were included without population restriction, comparing IMT intervention to no treatment, placebo or active control.

Results: We identified 10 RCTs involving 267 subjects (mean age range 51–71 years). IMT programs targeted maximum inspiratory pressure (MIP) and cardiovascular outcomes, using low (n=6) and moderate to high intensity (n=4) protocols, but the protocols varied considerably (duration: 1–12 weeks, frequency: 3–14 times/week, time: 10–30 mins). An overall increase of the MIP (cmH₂O) was observed (−27.57 95% CI −18.48, −37.45, I²=64%), according to weighted mean difference (95%CI), and was accompanied by a reduction of the low to high frequency ratio (−0.72 95% CI−1.40, −0.05, I²=50%). In a subgroup analysis, low- and moderate-intensity IMT treatment was associated with a reduction of the heart rate (HR) (−7.59 95% CI −13.96, −1.22 bpm, I²=0%) and diastolic blood pressure (DBP) (−8.29 [−11.64, −4.94 mmHg], I²=0%), respectively.

Conclusion: IMT is an effective treatment for inspiratory muscle weakness in several populations and could be considered as a complementary treatment to improve the cardiovascular system, mainly HR and DBP. Further research is required to better understand the above findings.

Effects of inspiratory muscle training on respiratory muscle strength, lung function, functional capacity and cardiac autonomic function in Parkinson's disease: Randomized controlled clinical trial protocol

BACKGROUND

Individuals with Parkinson's disease (PD), in addition to motor impairment, may evolve with respiratory and autonomic nervous system disorders. Currently, there are few studies with emphasis on muscle and pulmonary dysfunction and that verify the benefits of inspiratory muscle training (IMT) in this population.

AIM

The aim of this study was to evaluate whether IMT is effective for the improvement of respiratory muscle strength, lung function, thoracic mobility, functional capacity and cardiac autonomic function in PD.

METHODS

A randomized and controlled trial will be conducted with 26 participants with idiopathic PD, with aged between 50 and 65 years, in the Stages I to III by the Modified Hoehn and Yahr Scale. Respiratory muscle strength will be performed by manovacuometry and lung function by spirometry. Functional capacity will be evaluated by the 6-min walk test and autonomic cardiac function by heart rate variability. In addition, thoracic mobility measurement will also be performed. After the evaluations, these participants will be randomly assigned to two groups: the IMT group with Powerbreathe^® , which will perform the eight series of 2 min each, with 1 min of rest between them, totaling 30 min, at 60% of the maximum inspiratory pressure and the control group, who will perform the same training protocol but with the load maintained at 9 cmH₂ O. All participants will be submitted to the same motor training protocol.

CONCLUSION

It is expected that IMT increases the inspiratory muscle strength, contributing to the improved expiratory muscle strength, lung function, thoracic mobility, functional capacity and cardiac autonomic function in individuals with mild to moderate PD.

ERS statement on exercise training and rehabilitation in patients with severe chronic pulmonary hypertension

Objectives of this European Respiratory Society task force were to summarise current studies, to develop strategies for future research and to increase availability and awareness of exercise training for pulmonary hypertension (PH) patients.

An evidence-based approach with clinical expertise of the task force members, based on both literature search and face-to-face meetings was conducted. The statement summarises current knowledge and open questions regarding clinical effects of exercise training in PH, training modalities, implementation strategies and pathophysiological mechanisms.

In studies (784 PH patients in total, including six randomised controlled trials, three controlled trials, 10 prospective cohort studies and four meta-analyses), exercise training has been shown to improve exercise capacity, muscular function, quality of life and possibly right ventricular function and pulmonary haemodynamics. Nevertheless, further studies are needed to confirm these data, to investigate the impact on risk profiles and to identify the most advantageous training methodology and underlying pathophysiological mechanisms.

As exercise training appears to be effective, cost-efficient and safe, but is scarcely reimbursed, support from healthcare institutions, commissioners of healthcare and research funding institutions is greatly needed. There is a strong need to establish specialised rehabilitation programmes for PH patients to enhance patient access to this treatment intervention.

The elevation training mask induces modest hypoxaemia but does not affect heart rate variability during cycling in healthy adults

This study examined the acute effects of the elevation training mask (ETM) on haemodynamics and heart rate variability (HRV) at rest, during cycling, and during recovery in healthy adults. Fifteen healthy male (N=9) and female (N=6) adults (27.0 ± 1.14 years) completed two trials with the mask (MASK) and without the mask (CON). The 40-minute cycling exercise protocol included 10-minute phases of (1) rest, (2) 50% of VO_2peak cycling, (3) 70% of VO_2peak cycling, and (4) recovery. Blood pressure and pulse oximetry saturation (S_PO₂) were measured at each phase. An Actiwave-Cardio ECG monitor (CamNtech, UK) was used to measure HRV variables including time and frequency domains. A greater response in systolic blood pressure (p=.035) was observed at rest while S_PO₂ (p=.033) was lower during high-intensity cycling (70% of VO_2peak) in the MASK trial. The HRV indices were not different between trials during cycling. However, heart rate (p=.047) was greater while inter-beat interval and sympathovagal balance (the ratio between low-frequency and high-frequency components; ln LF/HF, p=.01) were lower in the MASK than the CON trials during recovery. Wearing an ETM during high-intensity cycling (70% of VO_2peak) induces modest hypoxaemia. Although this device did not affect HRV changes during cycling, it seems to delay the cardiac-autonomic recovery from exercise. Healthy adults may be required to perform high-intensity exercise with an ETM to simulate a hypoxic environment, but future studies are needed to determine whether repeated exposure to this condition provides similar benefits as altitude training.

Efeitos do treinamento muscular inspiratório no controle autonômico: revisão sistemática

RESUMO A disfunção do sistema nervoso autônomo tem papel importante na fisiopatologia de diversas doenças. Uma possível maneira de melhorar o controle autonômico é o treinamento muscular inspiratório (TMI), sendo o objetivo deste estudo revisar sistematicamente a literatura disponível sobre os efeitos desta modalidade. Dois revisores buscaram ensaios clínicos controlados e randomizados nas bases de dados MEDLINE, PEDro, SciELO e LILACS, avaliando também sua qualidade metodológica (escala de PEDro). Foram encontrados 181 artigos e, após verificar os critérios de elegibilidade, foram incluídos quatro pesquisas que avaliaram o efeito do TMI sobre o controle autonômico de participantes com fatores de risco para doenças cardiovasculares, por meio da variabilidade da frequência cardíaca (VFC) e dos níveis plasmáticos de noradrenalina. O TMI melhorou o controle autonômico em três estudos, reduzindo a atividade nervosa simpática (níveis plasmáticos de noradrenalina; LF u.n. - VFC) e aumentando a atividade nervosa vagal (HF u.n. - VFC). Conclui-se que o TMI parece ser uma alternativa terapêutica para melhorar o controle autonômico.

Cardiorespiratory interactions in humans and animals: rhythms for life

The cardiorespiratory system exhibits oscillations from a range of sources. One of the most studied oscillations is heart rate variability, which is thought to be beneficial and can serve as an index of a healthy cardiovascular system. Heart rate variability is dampened in many diseases including depression, autoimmune diseases, hypertension, and heart failure. Thus, understanding the interactions that lead to heart rate variability, and its physiological role, could help with prevention, diagnosis, and treatment of cardiovascular diseases. In this review, we consider three types of cardiorespiratory interactions: respiratory sinus arrhythmia (variability in heart rate at the frequency of breathing), cardioventilatory coupling (synchronization between the heart beat and the onset of inspiration), and respiratory stroke volume synchronization (the constant phase difference between the right and the left stroke volumes over one respiratory cycle). While the exact physiological role of these oscillations continues to be debated, the redundancies in the mechanisms responsible for its generation and its strong evolutionary conservation point to the importance of cardiorespiratory interactions. The putative mechanisms driving cardiorespiratory oscillations as well as the physiological significance of these oscillations will be reviewed. We suggest that cardiorespiratory interactions have the capacity to both dampen the variability in systemic blood flow as well as improve the efficiency of work done by the heart while maintaining physiological levels of arterial CO2. Given that reduction in variability is a prognostic indicator of disease, we argue that restoration of this variability via pharmaceutical or device-based approaches may be beneficial in prolonging life.

The ‘aerobic/resistance/inspiratory muscle training hypothesis in heart failure’

Evidence from large multicentre exercise intervention trials in heart failure patients, investigating both moderate continuous aerobic training and high intensity interval training, indicates that the ‘crème de la crème’ exercise programme for this population remains to be found. The ‘aerobic/resistance/inspiratory (ARIS) muscle training hypothesis in heart failure’ is introduced, suggesting that combined ARIS muscle training may result in maximal exercise pathophysiological and functional benefits in heart failure patients. The hypothesis is based on the decoding of the ‘skeletal muscle hypothesis in heart failure’ and on revision of experimental evidence to date showing that exercise and functional intolerance in heart failure patients are associated not only with reduced muscle endurance, indication for aerobic training (AT), but also with reduced muscle strength and decreased inspiratory muscle function contributing to weakness, dyspnoea, fatigue and low aerobic capacity, forming the grounds for the addition of both resistance training (RT) and inspiratory muscle training (IMT) to AT. The hypothesis will be tested by comparing all potential exercise combinations, ARIS, AT/RT, AT/IMT, AT, evaluating both functional and cardiac indices in a large sample of heart failure patients of New York Heart Association class II–III and left ventricular ejection fraction ≤35% ad hoc by the multicentre randomized clinical trial, Aerobic Resistance, InSpiratory Training OutcomeS in Heart Failure (ARISTOS-HF trial).

Can diaphragmatic breathing modify chest wall volumes during inspiratory loaded breathing in patients with heart failure?

BACKGROUND

Some inspiratory muscle training protocols for patients with heart failure report the request of diaphragmatic breathing during inspiratory loaded breathing. However, it is unclear whether this condition modifies the chest wall volumes.

OBJECTIVE

The primary purpose was to evaluate chest wall volumes during inspiratory loaded breathing as well as during inspiratory loaded breathing associated with diaphragmatic breathing in patients with heart failure.

METHODS

Sixteen men with heart failure functional class I to III, aged 50(SD=7) years were evaluated. Volumes of the pulmonary rib cage, abdominal rib cage and abdomen, as well as other breathing pattern variables, were assessed by optoelectronic plethysmography during quiet breathing, inspiratory loaded breathing, and inspiratory loaded breathing associated with diaphragmatic breathing.

RESULTS

Chest wall tidal volume significantly increased from quiet breathing 0.53(SD=0.14)L to inspiratory loaded breathing 1.33(SD=0.48)L and to inspiratory loaded breathing associated with diaphragmatic breathing 1.36(SD=0.48)L. A significant volume variation was observed on the three compartments (p<0.05 for all). During inspiratory loaded breathing associated with diaphragmatic breathing, patients showed increased abdominal volume compared to quiet breathing [0.28(SD=0.05) to 0.83(SD=0.47)L, p<0.001]; as well as from inspiratory loaded breathing [0.63(SD=0.23) to 0.83(SD=0.47)L, p=0.044]. No significant changes were observed between the two inspiratory loaded breathing conditions on the percentages of the contribution of each chest wall compartment for the tidal volume, respiratory rate, minute ventilation, and duty cycle.

CONCLUSION

When inspiratory loaded breathing was associated with diaphragmatic breathing, a higher volume in the abdominal compartment was obtained without significant changes in other breathing pattern variables.

Respiratory muscle training decreases diaphragm DNA damage in rats with heart failure

Respiratory muscle training (RMT) promotes beneficial effects on respiratory mechanics, heart and lung morphological changes, and hemodynamic variables in rats with heart failure (HF). However, the relation between RMT effects and diaphragm oxidative stress remains unclear. Therefore, the aim of this study was to evaluate the RMT effects on diaphragm DNA damage in HF rats. Wistar rats were allocated into 4 groups: sedentary sham (Sed-Sham, n = 8), trained sham (RMT-Sham, n = 8), sedentary HF (Sed-HF, n = 8), and trained HF (RMT-HF, n = 8). The animals underwent a RMT protocol (30 min/day, 5 days/week for 6 weeks), whereas sedentary animals did not exercise. Groups were compared by a two-way ANOVA and Tukey’s post hoc tests. In rats with HF, RMT promoted reduction in pulmonary congestion (p < 0.0001) and left ventricular end diastolic pressure (p < 0.0001). Moreover, RMT produced a decrease in the diaphragm DNA damage in HF rats. This was demonstrated through the reduction in the percentage of tail DNA (p < 0.0001), tail moment (p < 0.01), and Olive tail moment (p < 0.001). These findings showed that a 6-week RMT protocol in rats with HF promoted an improvement in hemodynamic function and reduces diaphragm DNA damage.

Effects of inspiratory muscle training in chronic heart failure patients: A systematic review and meta-analysis

OBJECTIVE

The aim of this study was to evaluate the effects of inspiratory muscle training (IMT) in chronic heart failure (CHF) patients.

DESIGN

We searched MEDLINE, EMBASE, Cochrane Library, CINHAL, and CBMdisc to collect controlled trials on the application of inspiratory muscle training in CHF patients from the establishment of these databases to November 2016. Two reviewers independently screened literature according to the inclusion and exclusion criteria, extracted data, and assessed the quality of literature. Meta-analysis was conducted by software RevMan5.3.

RESULTS

Eight studies involving 302 patients were identified. Meta-analysis indicated that IMT significantly improved PI_max , V_E /VCO₂ slope and dyspnea (weighted mean difference [WMD] = 16.52, 95% CI: 13.87-19.17, P < .01; WMD = -5.78, 95% CI: -7.72 to -3.85, P < .01; SMD = -0.95, 95% CI: -1.5 to -0.39, P < .01), and descriptive results showed that long-term IMT (≥6 weeks) can improve the quality of life of CHF patients, and patients in IMT group also have a significant improvement in 6-minute walking distance test (6-MWD).

CONCLUSION

IMT can improve pulmonary function, exercise tolerance, and quality of life of CHF patients and relieve the symptom of dyspnea.

Daily inspiratory muscle training lowers blood pressure and vascular resistance in healthy men and women

NEW FINDINGS

What is the central question of this study? What impact does inspiratory muscle training have on systemic vascular resistance, cardiac output and baroreflex sensitivity in adult men and women? What is the main finding and its importance? Inspiratory muscle training exerts favorable effects on blood pressure, vascular resistance and perception of stress. This exercise format is well-tolerated and equally effective whether implemented in men or women.

ABSTRACT

Previous work has shown that inspiratory muscle training (IMT) lowers blood pressure after a mere 6 weeks, identifying IMT as a potential therapeutic intervention to prevent or treat hypertension. Here, we explore the effects of IMT on respiratory muscle strength and select cardiovascular parameters in recreationally active men and women. Subjects were randomly assigned to IMT (n = 12, 75% maximal inspiratory pressure) or sham training (n = 13, 15% maximal inspiratory pressure) groups and underwent a 6-week intervention comprising 30 breaths day^-1 , 5 days week^-1 . Pre- and post-training measures included maximal inspiratory pressure and resting measures of blood pressure, cardiac output, heart rate, spontaneous cardiac baroreflex sensitivity and systemic vascular resistance. We evaluated psychological and sleep status via administration of the Cohen-Hoberman inventory of physical symptoms and the Epworth sleepiness scale. Male and female subjects in the IMT group showed declines in systolic/diastolic blood pressures (-4.3/-3.9 mmHg, P < 0.025) and systemic vascular resistance (-3.5 mmHg min l^-1 , P = 0.008) at week 6. There was no effect of IMT on cardiac output (P = 0.722), heart rate (P = 0.795) or spontaneous cardiac baroreflex sensitivity (P = 0.776). The IMT subjects also reported fewer stress-related symptoms (pre- versus post-training, 12.5 ± 8.5 versus 7.2 ± 9.7, P = 0.025). Based on these results, we suggest that a short course of IMT confers significant respiratory and cardiovascular improvements and parallel (modest) psychological benefits in healthy men and women.

Effects of inspiratory muscle training on cardiovascular autonomic control: A systematic review

PURPOSE

To carry out a systematic review to determine if inspiratory muscle training (IMT) promotes changes in cardiovascular autonomic responses in humans.

METHODS

The methodology followed the PRISMA statement for reporting systematic review analysis. MEDLINE, PEDro, SCOPUS and PubMed electronic databases were searched from the inception to March 2017. The quality assessment was performed using a PEDro scale. The articles were included if: (1) primary objective was related to the effects of IMT on the cardiovascular autonomic nervous system, and (2) randomized clinical trials and quasi-experimental studies. Exclusion criteria were reviews, short communications, letters, case studies, guidelines, theses, dissertations, qualitative studies, scientific conference abstracts, studies on animals, non-English language articles and articles addressing other breathing techniques. Outcomes evaluated were measures of cardiovascular autonomic control, represented by heart rate variability (HRV) and blood pressure variability (BPV) indexes.

RESULTS

The search identified 729 citations and a total of 6 studies were included. The results demonstrated that IMT performed at low intensities can chronically promote an increase in the parasympathetic modulation and/or reduction of sympathetic cardiac modulation in patients with diabetes, hypertension, chronic heart failure and gastroesophageal reflux, when assessed by HRV spectral analysis. However, there was no study which evaluated the effects of IMT on cardiovascular autonomic control assessed by BPV.

CONCLUSIONS

IMT can promote benefits for cardiac autonomic control, however the heterogeneity of populations associated with different protocols, few studies reported in the literature and the lack of randomized controlled trials make the effects of IMT on cardiovascular autonomic control inconclusive.

Inspiratory Muscle Training Is Associated With Improved Inspiratory Muscle Strength, Resting Cardiac Output, and the Ventilatory Efficiency of Exercise in Patients With a Fontan Circulation

BACKGROUND

Patients with a Fontan circulation have reduced exercise capacity and respiratory muscle strength. Inspiratory muscle training (IMT) improves exercise capacity and quality of life in adults with heart failure. We assessed whether 6 weeks of a home-based program of IMT improves inspiratory muscle strength and the ventilatory efficiency of exercise in adolescent patients with a Fontan circulation.

METHODS AND RESULTS

Twenty-three adolescent participants (aged 16±2 years) with a Fontan circulation underwent 6 weeks of IMT for 30 minutes daily. Respiratory muscle strength (maximal inspiratory pressure and expiratory pressure), lung function, and exercise capacity (cardiopulmonary exercise testing) were assessed. Fourteen of 23 participants also underwent exercise cardiac magnetic resonance imaging to examine the effects of IMT on cardiac output and systemic and pulmonary blood flow. Six weeks of IMT improved maximal inspiratory pressure by 36±24 cm H₂O (61±46%) with no change in maximal expiratory pressure. Ventilatory efficiency of exercise improved after 6 weeks of IMT (from 34.2±7.8 to 32.2±5.6, P=0.04). In those who underwent exercise cardiac magnetic resonance imaging, IMT increased resting cardiac output (from 4.2±1.2 to 4.5±1.0 L/min, P=0.03) and ejection fraction (from 50.1±4.3 to 52.8±6.1%, P=0.03).

CONCLUSIONS

Six weeks of IMT is associated with improved inspiratory muscle strength, ventilatory efficiency of exercise, and resting cardiac output in young Fontan patients. IMT may be a simple beneficial addition to the current management of Fontan patients, potentially reducing exercise intolerance and long-term morbidity and mortality.

Effects of inspiratory muscle exercise in the pulmonary function, autonomic modulation, and hemodynamic variables in older women with metabolic syndrome

The aim of the present study was to investigate the effects of inspiratory muscle exercise (IME) on metabolic and hemodynamic parameters, cardiac autonomic modulation and respiratory function of older women with metabolic syndrome (MS). For this, sixteen older women with MS and 12 aged-matched controls participated of the present study. Two days before and 2 days after the main experiment, fasting blood samples (i.e., total cholesterol, triglycerides and blood glucose), cardiac autonomic modulation (i.e., heart rate variability), and respiratory muscle function were obtained and evaluated. The sessions of physical exercise was based on a IME, which was performed during 7 days. Each session of IME was performed during 20 min, at 30% of maximal static inspiratory pressure. In the results, MS group presented higher levels of triglycerides, blood glucose, and systolic blood pressure when compared to control group. IME was not able to change these variables. However, although MS group showed impaired respiratory muscle strength and function, as well as cardiac autonomic modulation, IME was able to improve these parameters. Thus, the data showed that seven days of IME are capable to improve respiratory function and cardiac autonomic modulation of older women with MS. These results indicate that IME can be a profitable therapy to counteracting the clinical markers of MS, once repeated sessions of acute IME can cause chronical alterations on respiratory function and cardiac autonomic modulation.