Aim To understand how device-measured sedentary behaviour and physical activity are related to cardiovascular disease (CVD) events in older men, an age-group with high levels of physical inactivity and sedentary behaviour. Activity monitors permit investigation of different activity intensities, (including light activity which is hard to recall) and the pattern of accumulating activity, (such as doing moderate to vigorous physical activity (MVPA) in 10 min bouts) or breaking up periods of sedentary behaviour.
Methods Prospective population-based cohort study of 7735 men recruited from 24 UK General Practices in 1978–80. In 2010–12, 3137 surviving men were invited to complete a questionnaire about medical history and health behaviours and to wear an Actigraph GT3x accelerometer over the hip for 7 days. Physical activity intensity was categorised as sedentary: <100 counts/minute, light: 100–1040 counts/minute and moderate to vigorous PA (MVPA): >1040 counts/minute. A sedentary break was the interruption of a sedentary bout lasting >1 min by ≥1 min of activity >100 counts/minute. Men were followed up for CVD morbidity (ICD9 410–414 and 430–438) and mortality from 2010–12 to 1 st June 2016. Cox proportional hazards models estimated Hazard Ratios (HRs) for CVD according to physical activity measured in 2010–12, controlling for confounders.
Results 1,566/3137 (50%) men returned an accelerometer with data and 1528 (49%) had ≥600 minutes/day wear time on ≥3 days. 254 men with pre-existing CVD were excluded, leaving 1274 men. Participants’ mean age was 78.4 (range 71–92) years. After median 4.6 years follow-up, 82 first CVD events occurred in 1181 men with complete covariate data. For each additional 30 min in sedentary behaviour, light physical activity, 10 min in MVPA, or 1000 steps/day, hazard ratios for CVD mortality were 1.08 (95% CI 0.98, 1.18), 0.96 (95% CI 0.85, 1.08), 0.89 (95% CI 0.81, 0.98) and 0.86 (95% CI 0.77 to 0.96) respectively. Adjustments for confounders little changed the estimates. The hazard ratio for accumulating 150 min MVPA/week irrespective of bout length (achieved by 66% of men) was 0.54 (95% CI, 0.34 to 0.87) and for accumulating 150 min MVPA/week in bouts lasting ≥10 min (achieved by 16% of men) was 0.49 (95% CI, 0.21 to 1.13). Sedentary breaks were not associated with CVD events.
Discussion In older men, a higher number of steps per day or accumulating more MVPA (irrespective of bouts lasting ≥10 min) was associated with reduced CVD risk. Hence, in this population CVD prevention could focus on accumulating time in activities like brisk walking each day. Future studies should replicate analyses in women and younger populations.
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