Domains matter: Cross-sectional associations between mental well-being and domain specific physical activity and sedentary behaviour in n=31,818 adults in Scotland

Mental wellbeing is an important protective factor for health. This study aimed to investigate the domain-specific associations for physical activity and sedentary behaviours with different levels of mental wellbeing. We pooled data from the nationally representative 2012-2019 Scottish Health Surveys (31,818 adults (>= 16 years); 52.3% female). Respondents reported domain-specific physical activity over the previous four weeks and average domain-specific daily sitting time for week and weekend days. Mental wellbeing was assessed using the WarwickEdinburgh Mental Wellbeing Scale. Associations were investigated using cubic spline and multinomial regressions progressively adjusted for demographic variables, body mass index, self-reported general health, and other movement behaviours. The majority of the sample (71.2%) had a medium mental wellbeing score with 15.2% and 13.5% in the low and high categories respectively. The findings indicated that home-based heavy manual (including gardening and DIY), walking, sport and exercise, and leisure time sitting were all positively associated with mental wellbeing. There was no association evident for heavy housework or occupational sitting, and high levels of TV/screen time sitting were negatively associated with mental wellbeing. Activity at work presented a mixed picture. For walking and sport and exercise, the relationship differed by mental wellbeing level. The findings of this large population level study extend the argument that domains and types of activity matter, and not all physical activity and sedentary behaviour is equal in terms of mental wellbeing. Additionally, the relationship between some activity and mental wellbeing can vary depending on levels of mental wellbeing.