The prevalence of the iatrogenic functional decline is about 20 to 50% for the elderly after an hospitalization. The consequences are the functional incapacities, the mobility loss, the re-hospitalization, the falls and the important use of health care and health services. In this regard, the MSSS adopted in 2011 a framework making mandatory the set up of interventions to prevent the functional decline of hospitalized elderly in every hospital located in Quebec. The Geriatric Assessment Units (GAU) admit elderly around 80 years old who present complex health problems. The scientific literature has shown the effectiveness of rehabilitation programs to ensure the maintenance of functional capacities and the mobility of frail elderly. However, even with these knowledges, the prescription of physical exercises in the GAU does not seem to be integrated as a natural and systematic practice by health the professional. Our research team would like to implant the clinical tool PATH 2.0 that is a unique process of systematic prescriptions of adapted and specific physical activity program post-hospitalization in the GAU. The objective of this project is to evaluate the implementation of the clinical tool PATH 2.0 in different GAUs and to evaluate its efficiency and to estimate its cost-effectiveness regarding health care and service used. Finally, the conclusions would help to refine and identify the better procedures to use at short and medium term this clinical tool like a standard practice in GAU and to improve the health continuum of elderly.