A series of n-of-1 studies examining the interrelationships between social cognitive theory constructs and physical activity behaviour within individuals

Objectives: Research supports the ability of Social Cognitive Theory (SCT) to explain physical activity (PA) behaviour, but most studies have examined this theory between individuals in large group studies. The aim of the present study was to examine the interrelationships between SCT constructs and PA within individuals of varying activity levels. Design: correlational n-of-1 studies. Methods: Six adults aged 29-65 with varying levels of PA provided daily measures of PA, and completed probe measures over a four-week period of SCT constructs (e.g. barrier self-efficacy, goal setting, planning, social support, outcome expectations, perceived barriers, enjoyment). Data were analysed using cross-correlational time series analysis. Results: Cross-correlation analysis showed that at least one SCT construct was associated with PA in five participants, although no individual had the same pattern of associations across the study. On some occasions, SCT constructs predicted subsequent PA, but at other times, PA engagement caused a subsequent change in the SCT construct. There were also examples of PA and SCT constructs being concurrently associated. Conclusions: SCT factors are associated with variations in PA behaviour, but the cause and effect of these relationships within individuals is complex