Exercise but when, Morning or Afternoon?
The time of onset of myocardial infarction (heart attack) and other ischaemic heart events and arrhythmic episodes (irregularities of heart) display a circadian rhythm (variation of time of occurrence) with peak occurrence in the early morning between 6 am and noon. This may be related to morning surges of hormone cortisol, increased blood level of catecholamine and greater platelet agreeability that occurs in the morning as compared with the afternoon. Since exercise may also precipitate ischaemic heart events, it has been postulated that it is safer to exercise in the afternoon than in the morning. But there was no statistically significant difference between the risks of exercising in the morning vs. the afternoon. The risk of untoward cardiac events during regular exercise is low in patients with heart disease, whether they exercise in the morning or the afternoon. Data suggest that the answer to the clinical question of when patients with heart disease should perform regular, sub maximal exercise is clear: AM and PM are both safe.
