This is a pilot study for evaluating the feasibility of using High Intensity Interval Training in geriatric hospitalized patients compared to the standard current rehabilitation practice.

High Intensity Interval Training (HIIT) has shown a superior effectiveness and efficiency when compared to Moderate Intensity Continuous Training (MICT) in several types of patients and in healthy subjects. There are no data on HIIT in a general geriatric population. This study is a pilot study evaluating the feasibility of using HIIT in geriatric hospitalized patients compared to the standard current rehabilitation practice without HIIT. It is our desire to perform a larger randomized comparative trial between HIIT and MICT if the pilot study proves its feasibility.

Inclusion Criteria:

• Patients aged 65 years and older hospitalized for rehabilitation after an acute medical condition
• Expected duration of the rehabilitation ≥ 2 weeks
• Ability to follow instructions to perform a Timed up and Go Test
• Ability to perform exercises
• Willing to participate in 4 sessions of HIIT per week for 2 weeks

Exclusion Criteria:

• Any acute condition with tachycardia, hypotension or fever.
• Abnormal cycle ergometer stress test with
• significant ECG modification
• decrease of more than 20 mmHg of the blood pressure with exercise
• angina
• ST depression at a workload <6 METs
• Inability to reach an intensity of 15/20 in the Borg's scale of perceived exertion
• Any unresolved acute medical or surgical condition of the following kind:
• acute heart failure
• acute coronary syndrome < 1 month
• strole < 1 month
• active pericarditis / myocarditis / endocarditis
• thromboembolic disease with < 2 weeks of anticoagulation
• acute infection requiring intravenous treatment
• ongoing intravenous perfusion
• surgery < 2 months
• recent bone fracture
• Previous episode of primary cardiac arrest (ie, cardiac arrest that did not occur in the presence of an acute myocardial infarction or during a cardiac procedure).
• Severe heart failure (NYHA III and IV)
• Severe stenotic or regurgitant valvular disease
• Uncontrolled hypertension at rest (SBP≥160mmHg, DBP≥100mmHg)
• Uncontrolled dysrhythmia
• Non-sustained ventricular tachycardia with exercise
• Implanted defibrillator
• Obstructive cardiomyopathy
• Resting HR > 100/min
• Severe peripheral artery disease
• Severe COPD (VEMS < 50%)
• Exercise-induced asthma
• Oxygen dependency
• Muscular-skeletal anomaly that may limit exercise participation
• Delirium
• Inability to follow instructions
• Inability to consent