The treatment and follow-up of congestive heart failure (CHF) represents a major part of France's health expenses. The beneficial effects of cardiac rehabilitation is well established, especially regarding the reduction of dyspnea, exercise limitation and fatigue and leads ultimately to a better quality of life. Maintaining these benefits in secondary prevention requires an improvement in daily physical activity, which is challenging and supposes a close follow-up difficult to perform on a daily living basis. However, a better knowledge of the type and dose of daily physical activity of this population would be very beneficial for the practitioner to prescribe or advise individually the type and the dose of physical activity required to maintain the benefits of cardiac rehabilitation. To date, only a physical activity questionnaire adapted to CHF could provide information regarding both the type and dose of daily physical activity. Such a questionnaire has been developed by our research team and allows an estimation of daily energy expenditure as well as the daily energy expended in its physical activity dimensions (rest, activities < 3 MET, activities between 3 and 5 MET, and activities > 5 MET). During its first step of validation, daily and physical activity energy expenditure estimated by this questionnaire was correlated to various factors of physical condition and notably, to peak V'O2 (R=0.71), prognostic factor largely recognized in CHF. A second step of validation was a pilot study comparing the estimation of daily energy expenditure by the questionnaire with a measurement of free-living daily energy expenditure with the doubly labelled water (DLW) method in 11 middle-aged males patients suffering CHF (NYHA I to III). Daily energy expenditure estimated from the questionnaire was very close to daily energy expenditure measured from the DLW method (R2 = 0.81; individual relative error < 7%). However, the high cost of the DLW method reduced the population studied to a small sample, which is a major limitation of this study since the sample was somewhat different to general CHF population in France.