Device-captured incidental physical activity, sedentary behaviour and all-cause mortality risk

Background Incidental physical activity from normal daily living may be a more feasible approach to improve health status in adults who are unwilling or unable to complete traditional structured exercise. We aimed to determine if incidental physical activity can attenuate or eliminate the all-cause mortality risk associated with high-sedentary behaviour. Methods We examined the tertile-based joint associations of accelerometry-derived sedentary behaviour and (a) total incidental vigorous (VPA), (b) total incidental moderate to vigorous (MVPA), (c) vigorous intermittent lifestyle physical activity (VILPA; incidental bouts <1 min) and (d) moderate to vigorous intermittent lifestyle physical activity (MV-ILPA; incidental bouts <3 min) with mortality risk. Results The sample comprised 25 526 non-exercising adults from the UK Biobank (median age (IQR): 63.5 (11.4) years; 44.3% male). Over an 8.0-year median follow-up, 1139 mortality events occurred. Compared with the referent group (high physical activity and low sedentary behaviour), there was no association between sedentary behaviour and all-cause mortality risk in the high total VPA (HR: 1.29; 95% CI: 0.90, 1.84) or medium (HR: 1.22; 95% CI: 0.93, 1.62) and high (HR: 1.15; 95% CI: 0.80, 1.65) MVPA group. VILPA showed a similar pattern to total incidental VPA, offsetting risk in the medium (HR: 1.19; 95% CI: 0.86, 1.64) and high (HR: 1.16; 95% CI: 0.81, 1.66) categories. MV-ILPA had comparable associations to total incidental MVPA, offsetting risk in the medium (HR: 1.13; 95% CI: 0.85, 1.50) and high (HR: 1.22; 95% CI: 0.85, 1.74) categories. A daily duration of 3.4 min of VILPA or 25.2 min of MV-ILPA offset associations of sedentary behaviour with mortality. Conclusions Incidental VPA and MVPA offset all-cause mortality risk associated with high sedentary behaviour even if accrued in brief intermittent bursts.