Changes in physical activity, weight and wellbeing outcomes among attendees of a weekly mass participation event: a prospective 12-month study.

Background: Mass participation events are recognized as a way of engaging low-active individuals in health-enhancing physical activity, but there is a need to investigate the sustained effects on behaviour and health. This study aimed to examine changes in self-reported physical activity, weight and wellbeing over 12 months in participants of parkrun, a weekly mass participation 5 km running event. Methods: New parkrun registrants (n = 354) completed self-reported measures of physical activity, weight, happiness and stress, at registration, 6 months and 12 months. Objective data on attendance and fitness (i.e. run dates and finishing times) were obtained from the parkrun database. Results: Overall physical activity levels were high at baseline, but significantly increased over the first 6 months, before declining. By 12 months, weekly physical activity was 39 min higher than baseline. Significant reductions in body mass index were observed over 12 months, with a weight loss of 1.1% in the whole sample, and 2.4% among overweight participants. Modest increases in happiness and decreases in perceived stress were recorded. Run times suggested a 12% improvement in fitness during the study. Conclusion: Significant changes in weight, fitness and wellbeing outcomes indicate the public health benefits of regular participation in parkrun.