Changes in physical activity patterns after retirement within individuals: a series of n-of-1 natural experiments

Abstract

Background: Physical activity (PA) trajectories after retirement, and the determinants thereof, are likely to differ considerably between individuals. Methods: A series of n-of-1 studies were conducted with 7 participants approaching retirement. PA, measured by tri-axial accelerometry, and ecological momentary assessments of sleep, mood, tiredness, time pressure, stress, pain, as well as theory-based measures including intention, perceived control and priority for engaging in PA, were collected daily for a period of 4-6 months. The study period included time before and after a participant’s retirement date. Additional personalised variables were included as potential predictors of PA. Data were analysed using time series ARIMA models. Findings: PA trajectories differed considerably between participants; a significant increase or decrease in PA level after retirement was seen in some participants but no change in others. The predictors of daily PA differed between participants. Conclusions: The direction, magnitude and predictors of PA change vary considerably between individuals. N-of-1 methods can further understanding about individual patterns of behaviour. The predictors of behaviour unique to the individual can be identified which can help to inform personalised behaviour change interventions.