Effect of a new resistance training method on the metaboreflex in cardiac rehabilitation patients: a randomized controlled trial.

Patients with cardiac disease exhibit exaggerated sympathoexcitation, pressor, and ventilatory responses to muscle metaboreflex activation (MMA). However, the effects of cardiac rehabilitation (CR) and especially resistance training (RT) modalities on MMA are not well known. This study investigated how CR impacts MMA in such patients, specifically examining the effects of two different resistance training (RT) protocols following 12 weeks of CR. In addition to endurance exercises, 32 patients were randomized into either a 3/7 RT modality (comprising 5 sets of 3-7 repetitions) or a control (CTRL) modality (involving 3 sets of 9 repetitions), with distinct inter-set rest intervals (15 s for 3/7 and 60 s for CTRL). MMA, gauged by blood pressure (BP) and ventilatory (Ve) responses during a handgrip exercise at 40% effort and subsequent post-exercise circulatory occlusion, demonstrated CR's significant impact. Systolic BP, initially at + 28 ± 23% pre-CR, improved to + 11 ± 15% post-CR (P = .011 time effect; P = .131 group effect). Diastolic BP showed a similar trend, from + 27 ± 23% to + 13 ± 15% (P = .099 time effect; P = .087 group effect). Ve, initially at + 60 ± 39%, reduced to + 14 ± 19% post-CR (P < .001 time effect; P = .142 group effect). Critical parameters-maximal oxygen consumption, lean mass, hand grip, and quadriceps strength-exhibited parallel increases in both 3/7 and CTRL groups (P < .05 time effect; P > .3 group effect). Ultimately, CR demonstrated comparable improvements in MMA across both RT modalities, indicating its positive influence on cardiovascular responses and physical performance in individuals with cardiac conditions.

Autonomic and respiratory consequences of altered chemoreflex function: clinical and therapeutic implications in cardiovascular diseases.

The importance of chemoreflex function for cardiovascular health is increasingly recognized in clinical practice. The physiological function of the chemoreflex is to constantly adjust ventilation and circulatory control to match respiratory gases to metabolism. This is achieved in a highly integrated fashion with the baroreflex and the ergoreflex. The functionality of chemoreceptors is altered in cardiovascular diseases, causing unstable ventilation and apnoeas and promoting sympathovagal imbalance, and it is associated with arrhythmias and fatal cardiorespiratory events. In the last few years, opportunities to desensitize hyperactive chemoreceptors have emerged as potential options for treatment of hypertension and heart failure. This review summarizes up to date evidence of chemoreflex physiology/pathophysiology, highlighting the clinical significance of chemoreflex dysfunction, and lists the latest proof of concept studies based on modulation of the chemoreflex as a novel target in cardiovascular diseases.

Overstimulation of the ergoreflex-A possible mechanism to explain symptoms in long COVID.

Long COVID refers to a multitude of symptoms that persist long after SARS-CoV-2 infection. Fatigue and breathlessness are the most common symptoms of long COVID across a range of studies. They are also cardinal symptoms of chronic heart failure (CHF). In this review, we propose that fatigue and breathlessness in patients with long COVID may be explained by skeletal muscle abnormalities, in a manner similar to patients with CHF. The ergoreflex is a cardiorespiratory reflex activated by exercise, which couples ventilation and cardiovascular function to exercise intensity. At least part of the symptomatology of CHF is related to abnormal skeletal muscle and an enhanced ergoreflex, resulting in heightened sympathetic, vasoconstrictor and ventilator drives. Similarly, SARS-CoV-2 infection results in a hyperinflammatory and hypercatabolic state. This leads to reduction in skeletal muscle mass and altered function. We postulate that the ergoreflex is chronically overstimulated, resulting in fatigue and breathlessness. Exercise training preserves muscle mass and function as well as reduces ergoreflex activation; therefore may have a role in improving symptoms associated with long COVID. Should the ergoreflex be proven to be an important pathophysiological mechanism of long COVID, tailored exercise interventions should be trialed with the aim of improving both symptoms and perhaps outcomes in patients with long COVID.

The ergoreflex: how the skeletal muscle modulates ventilation and cardiovascular function in health and disease.

The control of ventilation and cardiovascular function during physical activity is partially regulated by the ergoreflex, a cardiorespiratory reflex activated by physical activity. Two components of the ergoreflex have been identified: the mechanoreflex, which is activated early by muscle contraction and tendon stretch, and the metaboreflex, which responds to the accumulation of metabolites in the exercising muscles. Patients with heart failure (HF) often develop a skeletal myopathy with varying degrees of severity, from a subclinical disease to cardiac cachexia. HF-related myopathy has been associated with increased ergoreflex sensitivity, which is believed to contribute to dyspnoea on effort, fatigue and sympatho-vagal imbalance, which are hallmarks of HF. Ergoreflex sensitivity increases significantly also in patients with neuromuscular disorders. Exercise training is a valuable therapeutic option for both HF and neuromuscular disorders to blunt ergoreflex sensitivity, restore the sympatho-vagal balance, and increase tolerance to physical exercise. A deeper knowledge of the mechanisms mediating ergoreflex sensitivity might enable a drug or device modulation of this reflex when patients cannot exercise because of advanced skeletal myopathy.

Menstrual phase does not influence ventilatory responses to group III/IV afferent signaling in eumenorrheic young females.

Estrogen can reduce sympathetic activity, but its effects on minute ventilation (VE) with group III/IV afferent activation remain unclear. This study examined the influence of estrogen on VE during lower-extremity exercise with group III/IV activation. Females completed two identical visits in follicular and ovulatory menstrual phases. Nine participants (age 25 ± 4 years) performed three minutes of baseline steady-state cycle ergometry and then group III/IV afferents were further activated with proximal thigh cuffs inflated to 20, 60, and 100 mmHg (randomized) for two minutes and five minutes of cycling between each occlusion. Metaboreflex was isolated by post-exercise circulatory occlusion. Ventilation was measured continuously and rating of perceived exertion (RPE) was recorded for each stage. During rest and exercise, VE (p < 0.001) and tidal volume (VT) (p = 0.033) were higher in the follicular than ovulatory phase. Minute ventilation, VT, and respiratory rate (RR) with ergoreflex and metaboreflex activation were similar across phases. With cuff occlusion of 100 mmHg, VE increased from baseline by 26.3 ± 7.0 L/min in the follicular phase (p < 0.001) and by 25.3±7.7 L/min in the ovulatory phase (p < 0.001), with no difference between phases (p> 0.05); RR and VT increased similarly with occlusion, also with no phase differences. In eumenorrheic females, menstrual phase influences ventilation but not ventilatory responses to group III/IV isolation.

[The medical social importance of functional disorders under chronic obstructive disease of lungs].

The chronic obstructive disease of lungs is considered as important problem of modern public health system. The disease is increasingly keenly reflected in agenda of our society, economic and social sphere of the state. The steadily progressing course of disease, disability and increasing economic costs assigns task of finding and improving diagnostic methods in real clinical practice. The purpose of the study is to assess the medical social significance of new approaches to studying functional status of patients with chronic obstructive disease of lungs in routine clinical practice. The sampling of 105 males were examined: 64 patients with chronic obstructive disease of lungs and 41 volunteers from control group without any diseases of respiratory system. All examined patients underwent spirometry, sixth minute step test, analysis of heart rate variability and test with external peripheral vascular occlusion. The study results established high level of importance of complex assessment of functional status of patients in routine clinical practice. The patients with chronic obstructive disease of lungs with respiratory failure demonstrated persistent hyperactivity of ergoreflex during test with external peripheral vascular occlusion. Therefore, method of assessing ergoreflex according to heart rate variability indices is applicable in clinic and has perspectives of implementation as mode of additional diagnostics of functional disorders.

Peripheral reflex feedbacks in chronic heart failure: Is it time for a direct treatment?

Despite repeated attempts to develop a unifying hypothesis that explains the clinical syndrome of heart failure (HF), no single conceptual paradigm for HF has withstood the test of time. The last model that has been developed, the neurohormonal model, has the great virtue of highlighting the role of the heart as an endocrine organ, as well as to shed some light on the key role on HF progression of neurohormones and peripheral organs and tissues beyond the heart itself. However, while survival in clinical trials based on neurohormonal antagonist drugs has improved, HF currently remains a lethal condition. At the borders of the neurohormonal model of HF, a partially unexplored path trough the maze of HF pathophysiology is represented by the feedback systems. There are several evidences, from both animal studies and humans reports, that the deregulation of baro-, ergo- and chemo-reflexes in HF patients elicits autonomic imbalance associated with parasympathetic withdrawal and increased adrenergic drive to the heart, thus fundamentally contributing to the evolution of the disease. Hence, on top of guideline-recommended medical therapy, mainly based on neurohormonal antagonisms, all visceral feedbacks have been recently considered in HF patients as additional potential therapeutic targets.

Activation of the ergoreceptors in cardiac patients with and without heart failure.

BACKGROUND: The presence of ergoreflex activity and its current relationship to hyperventilation and prognosis in cardiac patients is unclear. Therefore, we evaluated ergoreflex activity in cardiac patients with and without heart failure (CHF) as well as in healthy subjects, and we examined how ergoreceptor activity was related to a mortality risk score in CHF (MAGGIC). METHODS AND RESULTS: Twenty-five healthy subjects and 76 patients were included, among whom were 25 with ischemic heart disease (IHD), 24 with stable CHF, and 27 with unstable CHF. Ergoreflex activity was measured with a dynamic handgrip exercise, followed by post-handgrip regional circulatory occlusion (PH-RCO). Ergoreflex activity contributed significantly to ventilation (median [interquartile range] %V) in unstable CHF (81 [73-91] %V without PH-RCO, 92 [82-107] %V with PH-RCO, and 11 [6-20] difference in %V; P < .001) and was positively correlated with the MAGGIC risk score (Spearman ρ = 0.431; P = .002). No ergoreflex activity was observed in healthy subjects (-4 [-10 to 5] difference in %V), IHD (0 [-8 to 3] Diff in %V) and stable CHF (-3 [-11 to 6] difference in %V). CONCLUSIONS: Ergoreflex activity contributes to hyperventilation, but only in CHF patients with persistent symptoms, and is closely related to the MAGGIC risk score. Ergoreflex activity was not present in patients with IHD or stable CHF, suggesting other reasons for the increased ventilatory drive in those patients.