OBJECTIVE: To compare effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on platelet function in patients undergoing cardiac rehabilitation, as hyper-reactive platelets are involved in atherogenesis and atherothrombosis. METHODS: In this single-centre parallel group randomised controlled trial, male patients after an acute coronary syndrome under dual antiplatelet therapy performed MICT or HIIT+MICT for 12 weeks. Main outcome was platelet reactivity measured by the half-maximal concentration (EC50) of platelet agonist thrombin receptor-activating peptide-6 (TRAP-6) in terms of P-selectin expression. EC50 was determined at baseline, after 6 and 12 weeks, each time at physical rest and on exertion. RESULTS: 82 patients were randomised to MICT or HIIT+MICT. Mean (95% CI) baseline EC50 values at physical rest were 6.7 micro-M (6.3 micro-M to 7.0 micro-M) TRAP-6. After 6/12 weeks, 36/33 MICT and 34/28 HIIT+MICT patients were examined. HIIT+MICT patients had 0.9 micro-M (0.4 micro-M to 1.4 micro-M)/0.5 micro-M (-0.1 micro-M to 1.0 micro-M) higher EC50 values than MICT ones, and the propensity of their platelets to form aggregates with monocytes was significantly lower after 12 weeks. Short-term strenuous physical exertion was generally associated with platelet activation and an EC50 reduction of 0.7 micro-M (0.6 micro-M to 0.8 micro-M). HIIT+MICT patients tended to be fitter after 12 weeks. No serious harms were observed. CONCLUSIONS: Including HIIT in cardiac rehabilitation seems to confer additional benefits compared with MICT alone, which should be confirmed in clinical trials with hard endpoints. Exertion-induced platelet activation and hyper-reactivity occur despite dual antiplatelet therapy. TRIAL REGISTRATION NUMBER: NCT02930330; results.
Reproduced with permission from the BMJ Publishing Group.

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