Associations of sleep characteristics and fatigue with physical activity patterns and unmet physical activity need in old age

Abstract

Many older people are unwillingly excluded from physical activity, a situation termed unmet physical activity need. Poor sleep and fatigue can hinder opportunities for physical activity and potentially lead to unmet physical activity need. To alleviate fatigue, older people adopt adaptive behaviors that may manifest as a more fragmented physical activity. This dissertation had three aims: first, to study whether fragmented physical activity patterns are associated with poorer sleep-related characteristics and higher fatigability; second, to study whether higher fatigue and poorer sleep characteristics are associated with unmet physical activity need in old age; and third, to study whether lower physical activity and fatigue precede the development of unmet physical activity need. Data were drawn from three larger studies: the Life-Space Mobility in Old Age study (n=848), the Finnish Twin Study on Aging (n=344), and the Active Ageing – Resilience and External Support as Modifiers of the Disablement Outcome study (n=1 021), which included a subsample (n=485) participating in physical activity monitoring. The data were based on self-reports, laboratory assessments, and physical activity monitoring. The participants in the studies were aged 75 to 93 and community-dwelling. The results showed that more fragmented physical activity patterns were associated with higher physical fatigability and poorer sleep-related characteristics. Short sleep duration and higher physical fatigability had cross-sectional associations with unmet physical activity need. Higher fatigue and unmet physical activity need showed a reciprocal association, which was explained by poorer health, and lower physical activity levels. Finally, lower physical activity level predicted the development of unmet physical activity need. Assessment of physical activity fragmentation may be important in identifying those at risk for poorer sleep and higher physical fatigability. While poorer sleep and higher fatigue may limit opportunities for physical activity participation in old age, the will to be more physically active remains. The aging-related decline in physical activity is often unwanted, and hence many older people may need support in physical activity participation. The findings lay grounds for physical activity promotion among older people.