To attest if a cardiac fatigue appears (and to measure it if it does) during intense physical exercises in two groups of subjects:

• Canoeists from a training center of the French canoeing team during an intensive session of three weeks of endurance training;
• Young recruits in military school of officers in ground forces of the French army during an intensive.

Inclusion Criteria:

• Healthy men between 18 and 35 years old;
• Giving their writing informed consent;
• And affiliated to the French social security.

Exclusion Criteria:

• To be a smoker.
• To present any known pathology that forbids the realisation of any test, or that can alter the measurements: cardiovascular risk factors treated or not (diabetes, dyslipidaemia, arterial hypertension, obesity), cardiac arrhythmia, coronary disease, heart failure, cardiac pacemaker or defibrillator, valvular disease after surgery or not, kidneys failure with dialyse or not, kidney pulmonary cardiac or liver transplantation, chronic bronchopneumopathy, asthma, etc.
• To take any medication that could alter autonomic nervous system or cardiovascular adaptation to maximal exercise (anti-arrhythmia, anti-hypertensive, anti-inflammatory,…).
• Drinking exciting drinks (coffee or tee for example) in the 12h before the tests.
• To be under legal protection (trusteeship, guardianship) or to be deprived of liberty.