Aim. To assess the change in ergoreflex activity in heart failure patients with reduced left ventricular systolic function in the study of the effectiveness of physical training (PT) with original regimen, compared with PT with conventionally estimated regimen.Material and methods. Single-center open-label study of 297 patients with class III HF. The patients were divided into two groups: main group (MG) — patients, in whom the PT intensity was estimated based on lactate threshold (LT); comparison group (CG), in whom the PT intensity was estimated based on 60% VO2peak. We analyzed ergoreflex activity, the relationship of ergoreflex with exercise tolerance (ET), routine systemic inflammation markers, clinical manifestations of HF, and ET based on VO2peak.Results. An increase in gait velocity at the LT level after 3 months of PT was registered in 94% (n=210) of the MG patients. After 3 months, the PT regimen was recalculated according to 60% VO2реак; an increase in gait velocity at this level after 3 months of PT was registered in 70% of CG patients (n=35). The severity of HF decreased in both groups, but the dynamics was more pronounced in the MG, where class II was achieved by 75% of patients (in CG — 44%, p=0,003). In the MG, to a greater extent than in the CG, the ET increased. Ergoreflex activity (according to ΔVE) decreased by ≥15% in 230 (97%) MG patients and in 31 (63%) patients with CG. After the completion of the PT period, when in some patients the HF severity decreased to class II, we revealed a direct association of the ergoreflex value (according to ΔVE) with a greater severity of HF (r=-0,57, p=0,01) and the relationship between the decrease in ergoreflex activity (according to ΔVE), an increase in VO2LT (r=-0,55, p=0,001), VO2peak (r=0,49, p=0,001), a decrease in monocyte count (r=0,63, p=0,01).Conclusion. In stable patients with class III HF receiving the proper disease-modifying therapy, ergoreflex activity is increased and is associated with functional class, ET, and systemic inflammation activity. In the course of physical rehabilitation, a decrease in ergoreflex activity is accompanied by a decrease in functional class, an increase in EF, which is more pronounced with personalized aerobic exercise using LT regimen assessment.