Social Cognitive Mediators of the Effect of the MobileMums Intervention on Physical Activity

Objective: To explore whether improvements in physical activity following the MobileMums intervention were mediated by changes in Social Cognitive Theory (SCT) constructs targeted in the intervention (bather self efficacy, goal setting skills, outcome expectancy, social support, and perceived environmental opportunity for exercise). This paper also examined if the mediating constructs differed between initial (baseline to 6 weeks) and overall (baseline to 13 weeks) changes in physical activity. Methods: Secondary analysis of data from a randomized controlled trial involving 88 postnatal women (<12 months postpartum). Participants were randomized to receive either the 12-week MobileMums intervention or a minimal-contact control condition. Physical activity and proposed mediators were assessed by self-report at baseline, 6 weeks, and 13 weeks. Walking for Exercise frequency was assessed using the Australian Women's Activity Survey and frequency of moderate-to-vigorous physical activity (MVPA) was assessed using a single-item question. Results: Initial improvements in goal-setting skills mediated the relationship between experimental condition and initial changes in MVPA, alpha beta (95% CI) = 0.23(0.01, 0.59), and Walking for Exercise, alpha beta (95% CI) = 0.34(0.06, 0.73). Initial improvements in bather self efficacy mediated the relationship between experimental condition and initial change in MVPA, alpha beta (95% CI) = 0.36(0.12, 0.65), but not Walking for Exercise. None of the SCT outcomes significantly mediated the relationship between experimental condition and overall (baseline to 13 weeks) change in frequency of MVPA or Walking for Exercise. Conclusion: Future interventions with postnatal women using SCT should target barrier self-efficacy and goal setting skills in order to increase physical activity.