Chronic Intradialytic Exercise : a Cardioprotective Role (EX-CHRODIAL)

The main objective is to assess the effects of chronic intradialytic physical exercise on myocardial remodelling and regional function.

Background: Hemodialysis patients have a mortality rate 50 times higher than in the general population, and the cause remains cardiovascular in more than half of the cases. A deleterious morphological and functional cardiac remodelling is well established in these patients, the causes of which are both the presence of factors specific to renal disease (hemodynamic and non-hemodynamic) and co-morbidities (diabetes, hypertension, etc. .) but also to the hemodialysis (HD) procedure itself, due to the sudden hemodynamic changes it imposes, leading to repeated episodes of intradialytic hypotension (HID) and myocardial stunning. The latter are now documented as direct contributors to the increased mortality observed in HD patients compared to the general population. The introduction of intradialytic physical exercise in the therapeutic program of HD patient is now recommended and practised routinely in many countries, in Scandinavia in particular. Several meta-analyses have clearly established its safety. The beneficial role of chronic intradialytic exercise in improving dialysis efficiency, mental health and quality of life, as well as the inflammatory status of HD patients is also clearly demonstrated. Chronic intradialytic exercise is also associated with improvements in overall fitness level, a parameter closely linked to cardiovascular mortality. Applied acutely during dialysis, it could play a cardioprotective role (e.g; limiting myocardial stunning), allowing haemodynamic and cardiac functional stabilization during HD. However, to our knowledge, no study to date has investigated the long-term effects of intradialytic exercise on remodelling and overall and regional heart function. Aims: The main objective is to assess the effects of chronic intradialytic physical exercise on myocardial remodelling and regional function. The secondary objectives are to evaluate the effect of acute intradialytic exercise on myocardial stunning as well as the effect of chronic physical exercise on macro and microcirculatory vascular function, inflammation, physical fitness and health-related quality of life.

Acute phase : standard HD versus HD with acute intradialytic exercise (in HD-EX group only); Chronic phase : before and after an exercise training program of 16 weeks (HD-EX group) as well as before and after 16 weeks of standard HD (HD group)

1h of intradialytic execise, starting 30 min after hemodialysis beginning : 30 min of low-intensity (Borg Scale 11-14) aerobic exercise + 30 min of resistance training, frequency : 3 times a week for 16 weeks.

30 min of low-intensity (Borg Scale 11-14) aerobic exercise, starting 30 min after hemodialysis beginning

Myocardial longitudinal linear deformations (in percent) will be assessed by high-resolution echocardiography in deformation imaging mode.

Acute phase : just before and 90 and 210 minutes within standard dialysis or dialysis including acute exercise.

Myocardial longitudinal linear deformations (in percent) will be assessed by high-resolution echocardiography in deformation imaging mode.

Chronic phase : before (week 0) and after (week 17) an exercise training program of 16 weeks; each time in the same conditions as in acute phase (e.g. just before and 90 and 210 minutes within standard dialysis or dialysis including acute exercise).

Myocardial circumferential linear deformations (in percent) will be assessed by high-resolution echocardiography in deformation imaging mode.

Acute phase : just before and 90 and 210 minutes within standard dialysis or dialysis including acute exercise.

Myocardial circumferential linear deformations (in percent) will be assessed by high-resolution echocardiography in deformation imaging mode.

Chronic phase : before (week 0) and after (week 17) an exercise training program of 16 weeks; each time in the same conditions as in acute phase (e.g. just before and 90 and 210 minutes within standard dialysis or dialysis including acute exercise).

Left ventricular torsion (in degree) will be assessed by high-resolution echocardiography in deformation imaging mode.

Acute phase : just before and 90 and 210 minutes within standard dialysis or dialysis including acute exercise.

Left ventricular torsion (in degree) will be assessed by high-resolution echocardiography in deformation imaging mode.

Chronic phase : before (week 0) and after (week 17) an exercise training program of 16 weeks; each time in the same conditions as in acute phase (e.g. just before and 90 and 210 minutes within standard dialysis or dialysis including acute exercise).

The six-minute walking test (meters); maximal isometric force (newtons) during a knee-extension test and handgrip test using a dynamometer.

The 36-Item Short Form Health Survey questionnaire. The SF-36 consists of eight scaled scores, which are the weighted sums of the questions in their section. Each scale is directly transformed into a 0-100 scale on the assumption that each question carries equal weight. The lower the score the more disability.

The intimal plus media wall thickness (mm) of the right carotid artery will be measured using high-resolution echography.

Inclusion Criteria: No medical contraindication to physical activity Life expectancy greater than 6 months Patients on haemodialysis for more than 3 months Exclusion Criteria: Pregnancy Valvular heart disease, Unstable coronary artery disease Arteriopathy obliterating of the lower limbs stage III and IV Musculoskeletal problems Severe respiratory disease BMI> 35 Pacemaker, cardiac stimulation and automatic implantable defibrillator Heart transplant Uncontrolled arterial hypertension Ejection fraction <45%