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

Aerobic exercise training combined with local strength exercise restores muscle blood flow and maximal aerobic capacity in long-term Hodgkin lymphoma survivors

It is unclear whether muscle blood flow (MBF) is altered in long-term Hodgkin lymphoma (HL) survivors. We tested the hypothesis that 1) MBF response during mental stress (MS) is impaired in long-term HL survivors and 2) aerobic exercise training combined with local strength exercise (ET) restores MBF responses during MS in these survivors. Eighteen 5-year HL survivors and 10 aged-paired healthy subjects (HC) were studied. Twenty HL survivors were randomly divided into two groups: exercise-trained (HLT, n = 10) and untrained (HLUT, n = 10). Maximal aerobic capacity was evaluated by a cardiopulmonary exercise test and forearm blood flow (FBF) by venous occlusion plethysmography. MS was elicited by Stroop color and word test. ET was conducted for 4 mo, 3/wk for 60 min each session. The aerobic exercise intensity corresponded to anaerobic threshold up to 10% below the respiratory compensation point. The strength exercises consisted of two to three sets of chest press, pulley and squat exercises, 12-15 repetitions each exercise at 30-50% of the maximal voluntary contraction. Baseline was similar in HL survivors and HC, except peak oxygen consumption (peak V̇o2, P = 0.013) and FBF (P = 0.006) that were lower in the HL survivors. FBF responses during MS were lower in HL survivors (P < 0.001). ET increased peak V̇o2 (11.59 ± 3.07%, P = 0.002) and FBF at rest (33.74 ± 5.13%, P < 0.001) and during MS (24 ± 5.31%, P = 0.001). Further analysis showed correlation between the changes in peak V̇o2 and the changes in FBF during MS (r = 0.711, P = 0.001). In conclusion, long-term HL survivors have impaired MBF responses during MS. ET restores MBF responses during MS.NEW & NOTEWORTHY Long-term Hodgkin lymphoma (HL) survivors have impaired muscle blood flow responses during mental stress and decreased maximal aerobic capacity. Supervised aerobic exercise training combined with local strength exercises restores muscle blood flow responses during mental stress and maximal aerobic capacity in these survivors. These findings provide evidence of safety and effectiveness of exercise training in HL survivors. Moreover, they highlight the importance of exercise training in the treatment of this set of patients.

Physical capacity increase in patients with heart failure is associated with improvement in muscle sympathetic nerve activity

BACKGROUND

Exercise training improves physical capacity in patients with heart failure with reduced ejection fraction (HFrEF), but the mechanisms involved in this response is not fully understood. The aim of this study was to determine if physical capacity increase in patients HFrEF is associated with muscle sympathetic nerve activity (MSNA) reduction and muscle blood flow (MBF) increase.

METHODS

The study included 124 patients from a 17-year database, divided according to exercise training status: 1) exercise-trained (ET, n = 83) and 2) untrained (UNT, n = 41). MSNA and MBF were obtained using microneurography and venous occlusion plethysmography, respectively. Physical capacity was evaluated by cardiopulmonary exercise test. Moderate aerobic exercise was performed 3 times/wk. for 4 months.

RESULTS

Exercise training increased peak oxygen consumption (V̇O2, 16.1 ± 0.4 vs 18.9 ± 0.5 mL·kg-1·min-1, P < 0.001), LVEF (28 ± 1 vs 30 ± 1%, P = 0.027), MBF (1.57 ± 0.06 vs 2.05 ± 0.09 mL.min-1.100 ml-1, P < 0.001) and muscle vascular conductance (MVC, 1.82 ± 0.07 vs 2.45 ± 0.11 units, P < 0.001). Exercise training significantly decreased MSNA (45 ± 1 vs 32 ± 1 bursts/min, P < 0.001). The logistic regression analyses showed that MSNA [(OR) 0.921, 95% CI 0.883-0.962, P < 0.001] was independently associated with peak V̇O2.

CONCLUSIONS

The increase in physical capacity provoked by aerobic exercise in patients with HFrEF is associated with the improvement in MSNA.

Clinical aspects and targeted inspiratory muscle training in children and adolescents with Fontan circulation: a randomized controlled trial

Background

Since 1968, thousands of patients with a morphologically or functionally univentricular heart have been treated with a total cavopulmonary connection/Fontan operation. Because of the resulting passive pulmonary perfusion, blood flow is assisted by the pressure shift during respiration. Respiratory training is known to improve exercise capacity and cardiopulmonary function. However, there are limited data on whether respiratory training can also improve physical performance after Fontan surgery. The aim of the present study was to clarify the effects of six months of daily home-based inspiratory muscle training (IMT) aimed at increasing physical performance by strengthening respiratory muscles, improving lung function and peripheral oxygenation.

Methods

In this non-blinded randomized controlled trial, the effects of IMT on lung capacity and exercise capacity were measured in a large cohort of 40 Fontan patients (25% female; 12.3±2.2 years) who were under regular follow-up by the outpatient clinic of the Department of Congenital Heart Defects and Pediatric Cardiology of the German Heart Center Munich. After a lung function test and a cardiopulmonary exercise test, patients were randomly assigned in a parallel arm design to either an intervention group (IG) or a control group (CG) via stratified and computer-generated letter randomization from May 2014 to May 2015. The IG completed a daily, telephone-monitored IMT of three sets of 30 repetitions for six months with an inspiratory resistive training device (POWERbreathe medic^®), the CG continued their usual daily activities without an IMT until the second examination within the timeframe of November 2014 until November 2015.

Results

After six months of IMT, lung capacity values in the IG (n=18) did not increase significantly compared to the CG [n=19; ΔFVC: IG: 0.21±0.16 l vs. CG 0.22±0.31 l; P=0.946 (CI: -0.16, 0.17); ΔFEV1: CG: 0.14±0.30 vs. IG: 0.17±0.20 P=0.707 (CI: -0.20, 0.14)]. Exercise capacity did not improve significantly, yet the maximum workload achieved trended to improve with an increase of 14% in the IG vs. 6.5% in the CG [P=0.113 (CI: -15.8, 1.76)]. There was a significant increase of oxygen saturation at rest in the IG compared to the CG [IG: 3.31%±4.09% vs. CG: 0.17%±2.92%, P=0.014 (CI: -5.60, -0.68)]. Compared to the CG, the mean oxygen saturation at peak exercise no longer dropped below 90% in the IG. This observation is thus not statistically significant, yet of clinical relevance.

Conclusions

The results of this study show benefits of an IMT in young Fontan patients. Even if some data are not statistically significant, they may still be clinically relevant and may contribute to a multidisciplinary approach in patient care. IMT should therefore be an additional target and integrated into the training program to improve the prognosis of Fontan patients.

Trial Registration

German Clinical Trials Register; DRKS.de; registration ID: DRKS00030340.

Cardiovascular and autonomic dysfunction in long-COVID syndrome and the potential role of non-invasive therapeutic strategies on cardiovascular outcomes

A significant percentage of COVID-19 survivors develop long-lasting cardiovascular sequelae linked to autonomic nervous system dysfunction, including fatigue, arrhythmias, and hypertension. This post-COVID-19 cardiovascular syndrome is one facet of "long-COVID," generally defined as long-term health problems persisting/appearing after the typical recovery period of COVID-19. Despite the fact that this syndrome is not fully understood, it is urgent to develop strategies for diagnosing/managing long-COVID due to the immense potential for future disease burden. New diagnostic/therapeutic tools should provide health personnel with the ability to manage the consequences of long-COVID and preserve/improve patient quality of life. It has been shown that cardiovascular rehabilitation programs (CRPs) stimulate the parasympathetic nervous system, improve cardiorespiratory fitness (CRF), and reduce cardiovascular risk factors, hospitalization rates, and cognitive impairment in patients suffering from cardiovascular diseases. Given their efficacy in improving patient outcomes, CRPs may have salutary potential for the treatment of cardiovascular sequelae of long-COVID. Indeed, there are several public and private initiatives testing the potential of CRPs in treating fatigue and dysautonomia in long-COVID subjects. The application of these established rehabilitation techniques to COVID-19 cardiovascular syndrome represents a promising approach to improving functional capacity and quality of life. In this brief review, we will focus on the long-lasting cardiovascular and autonomic sequelae occurring after COVID-19 infection, as well as exploring the potential of classic and novel CRPs for managing COVID-19 cardiovascular syndrome. Finally, we expect this review will encourage health care professionals and private/public health organizations to evaluate/implement non-invasive techniques for the management of COVID-19 cardiovascular sequalae.

Effects of continuous aerobic training associated with resistance training on maximal and submaximal exercise tolerance, fatigue, and quality of life of patients post-COVID-19

BACKGROUND AND PURPOSE

Dyspnea, fatigue, and reduced exercise tolerance are common in post-COVID-19 patients. In these patients, rehabilitation can improve functional capacity, reduce deconditioning after a prolonged stay in the intensive care unit, and facilitate the return to work. Thus, the present study verified the effects of cardiopulmonary rehabilitation consisting of continuous aerobic and resistance training of moderate-intensity on pulmonary function, respiratory muscle strength, maximum and submaximal tolerance to exercise, fatigue, and quality of life in post-COVID-19 patients.

METHODS

Quasi-experimental study with a protocol of 12 sessions of an outpatient intervention. Adults over 18 years of age (N = 26) with a diagnosis of COVID-19 and hospital discharge at least 15 days before the first evaluation were included. Participants performed moderate-intensity continuous aerobic and resistance training twice a week. Maximal and submaximal exercise tolerance, lung function, respiratory muscle strength, fatigue and quality of life were evaluated before and after the intervention protocol.

RESULTS

Cardiopulmonary rehabilitation improved maximal exercise tolerance, with 18.62% increase in peak oxygen consumption (VO2peak) and 29.05% in time to reach VO2 peak. VE/VCO2 slope reduced 5.21% after intervention. We also observed increased submaximal exercise tolerance (increase of 70.57 m in the 6-min walk test, p = 0.001), improved quality of life, and reduced perceived fatigue after intervention.

DISCUSSION

Patients recovered from COVID-19 can develop persistent dysfunctions in almost all organ systems and present different signs and symptoms. The complexity and variability of the damage caused by this disease can make it difficult to target rehabilitation programs, making it necessary to establish specific protocols. In this work, cardiopulmonary rehabilitation improved lung function, respiratory muscle strength, maximal and submaximal exercise tolerance, fatigue and quality of life. Continuous aerobic and resistance training of moderate intensity proved to be effective in the recovery of post-COVID-19 patients.

Excess ventilation and exertional dyspnoea in heart failure and pulmonary hypertension

Increased ventilation relative to metabolic demands, indicating alveolar hyperventilation and/or increased physiological dead space (excess ventilation), is a key cause of exertional dyspnoea. Excess ventilation has assumed a prominent role in the functional assessment of patients with heart failure (HF) with reduced (HFrEF) or preserved (HFpEF) ejection fraction, pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). We herein provide the key pieces of information to the caring physician to 1) gain unique insights into the seeds of patients' shortness of breath and 2) develop a rationale for therapeutically lessening excess ventilation to mitigate this distressing symptom. Reduced bulk oxygen transfer induced by cardiac output limitation and/or right ventricle-pulmonary arterial uncoupling increase neurochemical afferent stimulation and (largely chemo-) receptor sensitivity, leading to alveolar hyperventilation in HFrEF, PAH and small-vessel, distal CTEPH. As such, interventions geared to improve central haemodynamics and/or reduce chemosensitivity have been particularly effective in lessening their excess ventilation. In contrast, 1) high filling pressures in HFpEF and 2) impaired lung perfusion leading to ventilation/perfusion mismatch in proximal CTEPH conspire to increase physiological dead space. Accordingly, 1) decreasing pulmonary capillary pressures and 2) mechanically unclogging larger pulmonary vessels (pulmonary endarterectomy and balloon pulmonary angioplasty) have been associated with larger decrements in excess ventilation. Exercise training has a strong beneficial effect across diseases. Addressing some major unanswered questions on the link of excess ventilation with exertional dyspnoea under the modulating influence of pharmacological and nonpharmacological interventions might prove instrumental to alleviate the devastating consequences of these prevalent diseases.

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.