Determinants of awareness, initiation and maintenance of physical activity among the over-fifties: a Delphi study.

To develop effective interventions to stimulate physical activity (PA), insight into its underlying variables is needed. The aim of this study was to obtain an overview of the most relevant determinants of awareness, initiation and maintenance of PA among the over-fifties by means of a three-round Delphi study. In the first round, 17 key-experts outlined possible relevant determinants into an open-ended electronic questionnaire. In the second round, 118 experts completed a structured electronic questionnaire that was based on the first round results, in which they scored each determinant on its relevance. In the third round, experts were asked to re-rate the relevance of each determinant, after feedback was given about the group median relevance score. After three rounds, the experts agreed on 30 relevant determinants of the three phases of PA. When compared with longitudinal studies, the Delphi study pointed out new concepts, such as several post-motivational and social and environmental determinants as possible relevant determinants, suggesting that this method has the potential to trace new and promising determinants. The results further showed that next to similarities, much dissimilarity in relevant determinants of awareness, initiation and maintenance of PA was found, suggesting that most determinants could be phase specific.