PHYSALYS is an observational multicenter study. It's an analytical study comparing 2 groups: patients exposed to physical activity and unexposed. The main objective of the study is to compare the evolution of glomerular filtration rate at inclusion and 12 months later between patients practicing physical activity and patients not practicing. If necessary, the renal disease-related complications, which are not influenced by physical activity: (type of kidney disease, age and tobacco), would be taken into account. TIRCEL patients with chronic kidney disease (CKD) at stages 3, 4 or 5 can be included in the study. Their serum creatinine data, 12 months prior to inclusion, is collected retrospectively. Patients are followed in the trial during 12 months. To evaluate physical activity, patients respond to Global Physical Activity Questionnaire 2 (GPAQ2) at inclusion and 12 months later. During this 12 months period, the same biological data are collected prospectively.

Inclusion Criteria:

• Members of TIRCEL (Traitement de l'Insuffisance Chronique en rhônE-aLpes) network for over a year and having at least two measurements of glomerular filtration rate with an interval of 9 to 12 months between the first and the last measurement
• Patients in stages 3, 4 or 5 of CKD
• No dialysis CKD patients
• Non transplanted CKD patients
• Patients seeing nephrologist
• Patients agreeing to be contacted for a phone call half an hour
• Adults patients (> 18 years)
• Patients not living in institution
• Patients being able to answer a questionnaire

Exclusion Criteria:

• Patients followed in the TIRCEL (Traitement de l'Insuffisance Chronique en rhônE-aLpes) network for less than one year or having less than 2 measurements of glomerular filtration rate with an interval of least 9 months or over 12 months between the first and the last measurement
• Patients in stages 1 or 2 of CKD
• CKD patients receiving dialysis
• Transplanted CKD patients
• Patients not seeing nephrologist
• Patients refusing to be contacted for a phone call half an hour
• Patients < 18 years
• Patients living in institution
• Patients unable to answer a questionnaire

Adult patients ( ≥ 18 years); members of TIRCEL network for over a year and having at least two measures of glomerular filtration rate with an interval of at least 9 to 12 months between the first and the last measurement; in CKD stage 3,4 or 5; not on dialysis and not transplanted, making a visit to their nephrologist; agreeing to be contacted at home for a phone call half an hour; not living in institution and being able to answer a questionnaire.