Micropatterns physical activity in relation to all-cause and cardiovascular disease mortality: the stealth lifestyle factor?

ImportancePhysical activity guidelines are predominantly based on questionnaire-based studies measuring only longer planned physical activity bouts (>10-15 continuous minutes). To date, short intermittent bouts of physical activity that may be beneficial for health ("micropatterns"), have counted very little towards physical activity guidelines (currently 150-300 minutes of moderate or 75-150 minutes of vigorous intensity activity per week). ObjectiveWe examined all-cause and cardiovascular disease (CVD) mortality associations of wearable device-captured activity accumulated through intermittent moderate to vigorous (IMVPA; [≤]3 min) and vigorous (IVPA; [≤]1 min) intensity bouts, by guideline adherence for a) active adults (eg. doing at least 150 mins/wk of moderate or 75 mins/wk of vigorous intensity physical activity), and b) inactive adults (not meeting the above amounts). DesignProspective cohort study SettingUK Biobank Participants62,899 adults (mean age 61 years, 55.7% female) with wrist-worn accelerometer data, followed up for an average of 8.0 (SD= 0.9) years ExposuresIntermittent moderate-vigorous (IMVPA; [≤]3 min) and vigorous (IVPA; [≤]1 min) intensity bouts; stratified by participants meeting and not meeting physical activity guidelines. Main outcomes and measuresAll-cause and CVD mortality obtained through linkage with the National Health Service (NHS) Digital of England and Wales or the NHS Central Register and National Records of Scotland. Cox restricted cubic spline regression were used to assess the dose-response associations. ResultsThere were 1,583 all-cause and 442 CVD deaths among 62,899 adults (mean age 61 years, 55.7% female). Micropatterns accrued IMVPA and IVPA showed linear beneficial dose response associations in both the inactive and active groups. We observed a 1.4 to 2.0-fold lower mortality risk among inactive compared to active adults. For all-cause mortality, a median 4.0 minutes/day of IVPA was associated with a hazard ratio (HR) of 0.40 [0.32, 0.52] in inactive adults and 0.74 [0.58, 0.95] in active adults, compared to not doing any IVPA. For CVD mortality, a median of 13.0 minutes/day of IMVPA was associated with an HR of 0.32 [0.22, 0.51] in inactive adults and 0.53 [0.37, 0.78] in active adults. Analogous patterns of dose-response were present when adherence to guidelines was assessed using questionnaire-based data that only considered continuous activity bouts lasting at least 10 minutes. Conclusions and relevanceAmong participants not meeting guidelines, intermittent moderate-vigorous physical activity showed stronger beneficial dose-response association with all-cause and CVD mortality, compared to active adults, highlighting potential health benefits from brief activity bursts for less active adults. Considering such activity patterns are hardly represented in the evidence used to develop current guidelines, our findings support the transition of future guidelines towards wearables-informed evidence.