Hemodynamic Effects of Dry Sauna Followed by Cold Water Immersion in Healthy Subjects

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.

Principal goal of study: to determine the safety of this practice. Secondary goals of study: to measure the blood pressure response, heart rate, presence of arrythmyas, cardiac output and cerebral perfusion during both conditions.

Primary endpoint: Change in systolic blood pressure from sauna (after 10 minutes ) to cold water (after one minute).

Physiologic measurements: continuous ECG monitoring, BP measurements at every 3 minutes during sauna and at one minute in the cold bath, gaz exchange with a portable equipment (Cosmed K4), bioimpedance and cerebral perfusion with a single frontal NIRS electrode.

Inclusion criteria

• Healthy women and men aged 40 and older with a recent complete medical evaluation including a normal resting ECG and a normal symptom-limited treadmill exercise test.

Exclusion criteria

• Any cardiac condition, abnormal exercise test, hypertension, type I diabetes and presence of any medications that may affect blood pressure.