Physical activity bout length and risk of major adverse cardiovascular events in adults with hypertension

BackgroundHypertension is a major risk factor for cardiovascular disease. Although it is well established that physical activity is cardioprotective, it is less clear how cardiovascular stress-related properties (i.e. intensity and bout length) determine future cardiovascular risk in adults with hypertension. ObjectivesWe examined the dose-response associations of moderate and vigorous physical activity bouts of variable length with major adverse cardiovascular events (MACE) and its sub-types (stroke, myocardial infarction, heart failure) in adults with hypertension. MethodsParticipants of the UK Biobank wearables sub-study with a clinical diagnosis of hypertension. Short bouts of moderate activity were classified as lasting up to 3 minutes and for vigorous activity up to 1 minute. Long bouts of moderate activity were classified as lasting >5 minutes, and for vigorous activity >2 minutes. In sensitivity analyses we also tested alternative vigorous intensity bout length definitions for short (up to 2 minutes) and long (> 3, >4, and >5 minutes). ResultsAmong 36,957 participants (62.1 (SD= 7.7) years; 58.4% female) with an average follow up of 7.9 (1.1) years, 1,374 MACE, 394 stroke, 623 myocardial infarction, and 357 heart failure events occurred. Moderate intensity was associated with lower risk of MACE and its individual sub-types for both short (<3 mins) and long (>5 mins) bout lengths with a stronger dose-response magnitude for longer bouts. We observed a consistent inverse dose response association for vigorous intensity accrued through short bouts (<1 min) and overall MACE, stroke, myocardial infarction, and heart failure risk. The median duration of 3.5 minutes/day corresponded to a hazard ratio (HR) ranging between 0.57 [0.39, 0.83] for heart failure to 0.66 [0.46, 0.96] for stroke. In contrast, vigorous intensity activity accrued through longer bouts showed a steep linear dose-response association for higher stroke risk. The median (6.0 minutes/day) and maximum (9.0 minutes/day) of activity accrued through vigorous bouts lasting >2 mins were associated with stroke HRs of 2.06 [1.38, 3.07] and 2.80 [1.72, 4.56], respectively. Additional analyses in 1 extra minute bout length increments revealed that the higher the "long bout" threshold the steeper the stroke risk, e.g the median of bouts lasting >5 mins (6.4 minutes/day) was associated with a HR of 2.69 [1.72, 4.21]. ConclusionFor adults with hypertension, moderate intensity and short bouts of vigorous intensity were beneficially associated with lower MACE, stroke, myocardial infarction, and heart failure risk. Vigorous intensity accumulated in long bouts showed a steep deleterious dose-response with stroke risk, and were not associated with lower overall MACE, myocardial infarction, or heart failure. Our results highlight the importance of bout length for vigorous intensity as a determining factor for cardiovascular health in adults with hypertension.