To determine the safety on sauna followed by cold water bath, a common practice in many countries, 30 healthy subjects aged 40 years and older will be at the Montreal Heart Institute Prevention and Cardiac Rehabilitation centre. A recent complete evaluation will have excluded any cardiac condition. Subjects will first spend 10 minutes in a dry sauna at 85 degrees celtius. Immediately after , subjects will be immersed in a cold water bath (ICool , Australia) at a temperature of 5 degrees celtius for approximately one minute. Blood pressure , ecg , gaz exchange and thoracic impedance will be measured during sauna and cold water bath.