Sarcopenia is associated with lower prognosis in solid tumors, but this has not been studied in bladder carcinoma requiring cystectomy. According to EWGSOP recommendations, the diagnosis of sarcopenia is based on walking speed, grip strength and muscle mass. These three elements can easily be measured (specially muscle mass measurement by bioimpedencemetry or tomodensitometry). This cohort study will collect clinical complementary elements to better understand the associated factors present with sarcopenia, in order to prepare an interventional preoperative physical reconditioning study. The mobility measurement will be carried out by the QAPPA questionnaire (validated in French in the elderly) and the quantitative measurement of activity and rest hours during a week by a wrist actimeter. Standardized geriatric data will also be collected: ADL, IADL for autonomy, MMSE for cognitive status, nutritional status (% weight loss, BMI), pain, GDS15 for depression screening, updated Charlson Comorbidity Index to identify polypathology and The STOPP tool for potentially inappropriate medication. Post-operative morbidity mortality at 30 days will be evaluated according to Clavien-Dindo classification. Investigators will also evaluate 6 months geriatric complications : falls, loss of autonomy and decreased mobility and physical activity, cognitive degradation, undernutrition, institutionalization