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.