Exercise intolerance and skeletal muscle metaboreflex activity in chronic heart failure: Do we need to recruit more muscle in exercise training?

Autonomic cardiovascular reflex control of hemodynamics during exercise in heart failure with reduced ejection fraction and the effects of exercise training

“…Combined interval and resistance training had statistically similar effects on respiratory drive compared to interval training alone in patients with HFrEF, but data indicated that combined training may have improved resting and exercise breathing pattern indices and P ET CO 2 more than intervals alone [145]. Inspiratory muscle training has produced benefits to exercise tolerance and potentially autonomic function in patients with HFrEF [146]. Clearly, exercise training program parameters (frequency, intensity, type, and time) are highly varied among autonomic studies in patients with HFrEF.…”

Understanding mechanoreflex and metaboreflex interactions – a great challenge

“…[27,28] On the other hand, EPR is impaired in these conditions which probably raises cardiovascular risk, decreases exercise capacity, and contributes to progression of muscle fatigue and dyspnea. [2,7,8,[29][30][31][32][33][34] The deterioration of EPR is characterized partially by hyperactivity of mechanoreflex [1,2,[7][8][9]23,31,[35][36][37][38][39][40][41][42][43][44] and partially by alteration in metaboreflex activity. The character of the latter in heart failure is controversial -some experiments show abnormally high response of metaboreflex, [7,8,23,31,[37][38][39][40][41]45,46] whereas other studies report diminished activation.…”

“…According to "muscle hypothesis" of heart failure and its neurohormonal component -contribution of EPR to exercise intolerance in heart failure patients is probably greater than contribution of hemodynamic alterations, such as decline in left ventricular ejection fraction and cardiac output. [31,32,51] This hypothesis explains startling observation that despite normalization of cardiovascular parameters in heart transplant recipients, exercise tolerance remains impaired. [52,53] Training programs applied in previous experiments included 6-week of forearm exercise, [7,50] 7-week treadmill training, [47] 4-week inspiratory muscle training, [48] 6-month exercise-based cardiac rehabilitation [49] resulted mainly in reduction in blood pressure, minute ventilation, vascular resistance, and MSNA in response to acute physical activity.…”

“…[54] Lately, it was suggested that recruitment of more muscle mass in exercise programs may be beneficial in restoring normal EPR functioning in patients with heart failure. [32] However, further studies are warranted to determine the optimal training regimen.…”