Intradialytic Exercise With Blood Flow Restriction in Hemodialysis Patients

The main objective is to evaluate in hemodialysis patients the effects of two intradialytic rehabilitation programs based on physical exercise, with or without the application of blood flow restriction, on myocardial stunning and morpho-functional cardiac remodelling, compared with usual care (i.e., dialysis without exercise). In addition, the investigators will also assess the acute effects (i.e., a single session for each condition) of physical exercise, with or without blood flow restriction, on myocardial stunning at the end of dialysis. In comparison with a conventional exercise program, the combination of physical exercise with blood flow restriction, which synergistically and additively activates intramuscular signalling pathways related to both exercise and ischaemia, is hypothesised to result in: 1. A greater intradialytic cardioprotection, as demonstrated by a greater reduction in myocardial stunning at the end of dialysis (both in acute and chronic applications), with underlying mechanisms involving systemic and neuro-humoral pathways; 2. Significant improvements in morpho-functional cardiac remodelling, attenuation of arrhythmic disturbances, and enhancement of aerobic capacity, muscle strength, and muscle mass-effects not observed with exercise alone without blood flow restriction, considering the low exercise intensity used in the current rehabilitation program (chronic application only). This is a three-arm randomised clinical trial with parallel groups: standard hemodialysis (HD-CONTChro), a rehabilitation program with intradialytic exercise without vascular occlusion (HD-EXChro), and a rehabilitation program with intradialytic exercise with vascular occlusion (HD-BFREChro), with a 1:1:1 allocation ratio. To investigate the acute effects of the interventions, all patients will undergo, in a randomized order, one session of each of the three dialysis modalities-standard hemodialysis (HD-CONTacute), hemodialysis with exercise without vascular restriction (HD-EXacute), and hemodialysis with exercise with vascular restriction (HD-BFREacute)-prior to initiation of the chronic phase of the study.