Should we work smarter or harder for our health? A comparison of intensity and domain-based time-use compositions and their associations with cognitive and cardiometabolic health

BACKGROUND Each day is made up of a composition of ‘time-use behaviours’. These can be classified by their intensity (e.g., light or moderate-vigorous physical activity (PA)) or domain (e.g., chores, socialising). Intensity-based time-use behaviours are linked with cognitive function and cardiometabolic health in older adults, but it is unknown whether these relationships differ depending on the domain (or type/context) of behaviour. METHODS This study included 397 older adults (65.5 ± 3.0 years, 69% female, 16.0 ± 3.0 years education) from Adelaide and Newcastle, Australia. Time-use behaviours were recorded using the Multimedia Activity Recall for Children and Adults (MARCA), cognitive function was measured using the Addenbrooke’s Cognitive Examination III (ACE-III) and Cambridge Neuropsychological Test Automated Battery (CANTAB), and systolic and diastolic blood pressure, total cholesterol and waist-hip ratio were also recorded. Two 24-hr time-use compositions were derived from each participant’s MARCA, including a four-part intensity composition (sleep, sedentary behaviour, light and moderate-vigorous PA) and an eight-part domain composition (Sleep, Self-Care, Chores, Screen Time, Quiet Time, Household Administration, Sport/Exercise, and Social). RESULTS Linear regressions found significant associations between the domain composition and both ACE-III (p=0.010) and waist-hip ratio (p=0.009), and between the intensity composition and waist-hip ratio (p=0.025). Isotemporal substitution modelling demonstrated that the domains of sedentary behaviours and PA impacted their associations with ACE-III, whilst any PA appeared beneficial for waist-hip ratio. CONCLUSIONS Findings suggest the domain of behaviour should be considered when aiming to support cognitive function, whereas for cardiometabolic health, it appears sufficient to promote any type of PA