Abstract
BackgroundCross-sectional relationships between physical activity and health have been explored extensively, but less is known about how physical activity changes with time in older people. The aim of this study was to assess baseline predictors of how objectively measured physical activity changes with time in older people.MethodsLongitudinal cohort study using data from the Physical Activity Cohort Scotland. A sample of community-dwelling older people aged 65 and over were recruited in 2009–2011, then followed up 2–3 years later. Physical activity was measured using Stayhealthy RT3 accelerometers over 7 days. Other data collected included baseline comorbidity, health-related quality of life (SF-36), extended Theory of Planned Behaviour Questionnaire and Social Capital Module of the General Household Survey. Associations between follow-up accelerometer counts and baseline predictors were analysed using a series of linear regression models, adjusting for baseline activity levels and follow-up time.ResultsFollow up data were available for 339 of the original 584 participants. The mean age was 77 years, 185 (55%) were female and mean follow up time was 26 months. Mean activity counts fell by between 2% per year (age < =80, deprivation decile 5–10) and 12% per year (age > 80, deprivation decile 5–10) from baseline values. In univariate analysis age, sex, deprivation decile, most SF-36 domains, most measures of social connectedness, most measures from the extended Theory of Planned Behaviour, hypertension, diabetes mellitus, chronic pain and depression score were significantly associated with adjusted activity counts at follow-up. In multivariate regression age, satisfactory friend network, SF-36 physical function score, and the presence of diabetes mellitus were independent predictors of activity counts at follow up after adjustment for baseline count and duration of follow up.ConclusionsHealth status and social connectedness, but not extended Theory of Planned Behaviour measures, independently predicted changes in physical activity in community dwelling older people.
Highlights
Cross-sectional relationships between physical activity and health have been explored extensively, but less is known about how physical activity changes with time in older people
We report the results of follow-up measurements of physical activity taken 2–3 years after the baseline visit in the Physical Activity Cohort Scotland (PACS) cohort, and examine the factors predicting change in objectively measured physical activity in this cohort of older, community dwelling people
Key findings We found that objectively measured physical activity declined in our cohort over a two year follow up period, and that older age at baseline, lower activity count at baseline, an unsatisfactory friendship network, lower self-reported physical functioning and the presence of diabetes mellitus all independently predicted a lower adjusted physical activity count at follow up
Summary
Cross-sectional relationships between physical activity and health have been explored extensively, but less is known about how physical activity changes with time in older people. Physical activity promotion has often focussed on vigorous activity [3], and interventions have often targeted individual-level factors at the expense of social and environmental factors [4] Such approaches are unlikely to be sufficient, and successful strategies to encourage physical activity in later life are likely to require complex interventions aimed at modifying several factors. Many previous studies have not measured activity objectively, instead relying on subjective reports of activity, often using questionnaires. Such approaches are known to lack accuracy in older people as well as younger people [11, 12], and there is a clear need for studies using objective methods of capturing how much PA older people undertake in their daily lives
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