TENS intervention consisted of continuous flow, symmetrical and rectangular TENS biphasic pulses. The frequency ofstimulation was 80 Hz and the pulse duration was 150 μs, with the intensity in adjusted to the point of muscle contraction.

The frequency of stimulation was 80 Hz and the pulse duration was 150 μs, equipment did not provide stimulation current.

Adhesive electrodes (MultiStick®, USA) were placed on each side, about 3 cm to the right and left of midline vertebral process, at C7 (Channel 1) and T4 (Channel 2).

Applanation tonometry (AT) accurately reflects arterial stiffness method and has demonstrated a strong correlation with ventricular-vascular coupling. Increased arterial stiffness and wave reflection have also been reported in patients with systolic and diastolic HF.

Cardiopulmonary exercise testing (CPX) is a highly reliable and valid approach to assessing aerobic performance. It is a well-accepted assessment technique in the HF population with American and European associations endorsing its use. CPX is most often performed on a treadmill or cycle ergometer using ramping protocols and the addition of ventilatory expired gas analysis to the standard exercise test enables measurement of oxygen consumption (VO2), carbon dioxide production (VCO2) and minute ventilation (VE) over time. Moreover, CPX provides a host of variables that are predictive of adverse events in HF patients, including peak VO2, the VE/VCO2 slope and the oxygen uptake efficiency slope (OUES).