Reallocating time between sleep, sedentary and active behaviours: Associations with obesity and health in Canadian adults.

BACKGROUND: Moderate-to-vigorous physical activity (MVPA) and sleep are positively associated with adults' health, while the association with sedentary behaviour (SED) is negative. Light-intensity physical activity (LPA) is emerging as an independent predictor of improved cardiovascular health. The health impacts of each of these factors have been examined in isolation, but interest has increased in associations between health and movement behaviours collectively.

DATA AND METHODS: This analysis examines how reallocating time between movement behaviours is associated with obesity and with self-rated general and mental health. Data for 18- to 79-year-olds (n = 10,621) were collected from 2007 through 2015 as part of the Canadian Health Measures Survey. LPA, MVPA, and SED were measured using the Actical accelerometer. Body mass index (BMI) and waist circumference (WC) were directly measured. Sleep and general and mental health were self-reported.

RESULTS: Reallocation of 30 minutes from SED, LPA or sleep to MVPA was associated with a lower BMI and smaller WC, particularly for older and overweight/obese individuals. Time reallocation from SED to LPA was associated with lower BMI and smaller WC in respondents who were aged 50 or older or who were overweight/obese. Time reallocated from SED to any other movement behaviour was associated with decreased odds of reporting poor/fair rather than excellent general health. Time reallocation from SED to LPA or to sleep, but not to MVPA, was associated with decreased odds of reporting poor/fair rather than excellent mental health.

DISCUSSION: These findings confirm previous research indicating a strong association between MVPA and markers of obesity and health, particularly among older and overweight/obese individuals. This study also provides evidence that increasing LPA is an important health promotion message for these two subpopulations.