Habit as moderator of the intention-physical activity relationship in older adults: a longitudinal study

This longitudinal study examined whether habit strength moderates the intention-physical activity (PA) relationship in older adults, within the framework of the attitude-social influences-efficacy (ASE) model and the theory of planned behaviour (TPB). A total of 1836 older adults (Mage = 62.95 years, SDage = 8.17) completed a questionnaire on social cognitive constructs and PA habit strength at baseline, and six months later a measure of PA. Three PA habit groups (i.e., low, medium and high) were composed, based on tertiles of the mean index score. Multi-group structural equation modelling analyses showed that intention significantly determined PA behaviour only in participants with a low or medium habit strength towards PA. This result suggests that PA is not intentional at high levels of habit strength and demonstrates the usefulness of incorporating habit in the ASE and TPB models. Results also showed that about half of the participants with a strong PA habit did not meet the recommended PA level. As strong habits may prevent intentional behavioural change and may hinder the receptiveness and openness for informational PA change strategies, additional intervention strategies, such as awareness raising and the use of implementation intentions, are needed for strongly habitual, but insufficiently active older adults.