The World Health Organization has identified intrinsic capacity and functional ability as key constructs in enabling healthy ageing. However, functional ability is distinct from actual levels of social and physical participation, which research has shown to be associated with health and wellbeing. This study distinguishes between functional ability and actual levels of social and physical participation, and utilizes the International Classification of Functioning, Disability and Health framework to examine the relationship between IC and the two constructs.

This study utilizes cross-sectional self-reported data from a nationally representative panel of Singapore residents aged 56–75 (N = 6,434). We performed structural equation modelling to compare the direct and indirect effects (mediated by IADLs) of intrinsic capacity on social participation. Intrinsic capacity is modelled as a second-order model, and its 5 domains are assessed using self-reported indicators. IADLs was based on participants’ self-reported difficulty in completing 7 instrumental daily activities. Social participation was measured using participants’ frequency of engagement in various activities.

Intrinsic capacity is positively associated with higher levels of social participation among middle-aged and older adults aged 56–75 (β = 0.287, 95% CI [0.156, 0.414]) even after controlling for IADLs. The direct effect of intrinsic capacity on social participation accounts for 77.4 % of the total effect, while the indirect effect through IADLs accounts for 22.6% of the total effect.

Intrinsic capacity is associated with social and physical participation directly and indirectly through IADLs. This study emphasizes the need for healthcare interventions aimed towards the promotion of healthy ageing to adopt a holistic approach that enhance IC across its five domains, ensuring both social and physical participation and functional independence of older adults.