Cross-sectional associations between sleep duration, sedentary time, physical activity, and adiposity indicators...

Sleep duration, sedentary behaviour, and physical activity are three co-dependent behaviours that fall on the movement/non-movement intensity continuum. Compositional data analyses provide an appropriate method for analyzing the association between co-dependent movement behaviour data and health indicators. The objectives of this study were to examine: (1) the combined associations of the composition of time spent in sleep, sedentary behaviour, light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA) with adiposity indicators; and (2) the association of the time spent in sleep, sedentary behaviour, LPA, or MVPA with adiposity indicators relative to the time spent in the other behaviours in a representative sample of Canadian preschool-aged children.

Participants were 552 children aged 3 to 4 years from cycles 2 and 3 of the Canadian Health Measures Survey. Sedentary time, LPA, and MVPA were measured with Actical accelerometers (Philips Respironics, Bend, OR USA), and sleep duration was parental reported. Adiposity indicators included waist circumference (WC) and body mass index (BMI) z-scores based on World Health Organization growth standards. Compositional data analyses were used to examine the cross-sectional associations.

The composition of movement behaviours was significantly associated with BMI z-scores (p = 0.006) but not with WC (p = 0.718). Further, the time spent in sleep (BMI z-score: γ _sleep  = -0.72; p = 0.138; WC: γ _sleep  = -1.95; p = 0.285), sedentary behaviour (BMI z-score: γ _SB  = 0.19; p = 0.624; WC: γ _SB  = 0.87; p = 0.614), LPA (BMI z-score: γ _LPA  = 0.62; p = 0.213, WC: γ _LPA  = 0.23; p = 0.902), or MVPA (BMI z-score: γ _MVPA  = -0.09; p = 0.733, WC: γ _MVPA  = 0.08; p = 0.288) relative to the other behaviours was not significantly associated with the adiposity indicators.

This study is the first to use compositional analyses when examining associations of co-dependent sleep duration, sedentary time, and physical activity behaviours with adiposity indicators in preschool-aged children. The overall composition of movement behaviours appears important for healthy BMI z-scores in preschool-aged children. Future research is needed to determine the optimal movement behaviour composition that should be promoted in this age group.