The purpose of this study is to determine whether high intensity interval training (INT) is more effective in suppressing platelet reactivity than continuous, moderate intensity training (CONT) in patients undergoing cardiac rehabilitation after percutaneous coronary intervention.

Background: Platelets play an important role in cardiovascular disease: First, they promote the development of atherosclerotic lesions, and second, platelets form vessel occluding thrombi on top of (ruptured) lesions, ultimately leading to thrombotic events like myocardial infarctions (MCI). Whereas acute, strenuous exercise causes platelet activation and transiently increases the risk for MCIs, long-term chronic exercise training results in a clear reduction of both platelet activation and MCI incidence.

Exercise training plays a key role in cardiac rehabilitation, since improvements in cardiorespiratory fitness (CRF) are associated with decreased mortality in these patients. With respect to CRF improvements, high-intensity interval training has been demonstrated to be more effective than moderate-intensity continuous exercise. However, the beneficial effect of high-intensity interval training on platelet function in patients with cardiovascular disease has never been investigated.

Scientific question: The aim of this study is to determine the effect of interval training in cardiac rehabilitation on platelet function.

Hypotheses: Cardiac rehabilitation with interval training components (INT) reduces

1. platelet activation and platelet reactivity at physical rest
2. changes of platelet activation and -reactivity induced by acute, strenuous exercise to a greater extent than cardiac rehabilitation consisting exclusively of moderate-intensity continuous exercise training (CONT).

Work program: 80 patients at the beginning of phase II cardiac rehabilitation will be randomly assigned to an interval group or to a control group. In both groups, patients will exercise 4x / week for 12 weeks. At the beginning, after 6 weeks and at the end an exercise test will be carried out. Blood will be taken before (platelet function at rest) and immediately after each exercise test (platelet function after acute, strenuous exercise). Basal platelet activation as well as platelet responsiveness towards a platelet agonist (platelet reactivity) will be analyzed.

Inclusion Criteria:

• No regular exercise training within the last 6 months
• Dual anti-platelet therapy (low-dose aspirin plus ADP(adenosine diphosphate)-receptor antagonist)
• Status post percutaneous coronary intervention after recent acute coronary syndrome as underlying reason for current rehabilitation
• Eligibility for outpatient cardiac rehabilitation according to Table I in Niebauer et al. 2013 (PMID: 22508693)

Exclusion Criteria:

• Type II diabetes mellitus
• Aortic aneurysm / dissection
• Uncontrolled hypertension (>180/110 mmHg)
• Pulmonary hypertension (>55 mmHg)
• Previously known hereditary platelet disorders
• Disorders of plasmatic coagulation
• Anemia (Hb < 13g/dl)
• History of end-stage liver or kidney disease