Evaluating movement breaks as a public health strategy to mitigate the harms of prolonged sitting: a large-scale pragmatic intervention.

Abstract

Brief, regular movement breaks have been proposed as a public health strategy to offset the harms of prolonged sedentary behaviour; however, their real-world viability is unclear. This study aimed to assess the implementation potential, effectiveness on psychosocial outcomes and optimal dosing of movement breaks in naturalistic settings. Adults (n=19 342) enrolled in a 2-week pragmatic intervention embedded within an interactive podcast; of whom 59.4% (n=11 484) initiated the intervention. Participants took 5-minute walking breaks at their self-selected break frequency (three arms: every 30, 60 or 120 min). Implementation potential was assessed using the Feasibility, Acceptability and Appropriateness of Intervention Measures (FIM, AIM, IAM). Fatigue, positive affect and negative affect were assessed pre-intervention and post-intervention. All arms exceeded the viability threshold (>3.0) for implementation outcomes. Feasibility was higher at lower break frequencies (FIM: 30 min=3.41, 60 min=3.80, 120 min=4.01), while acceptability and appropriateness were high across arms (AIM: 30 min=3.91, 60 min=4.03, 120 min=4.03; IAM: 30 min=4.00, 60 min=4.04, 120 min=3.99). Reported fatigue and negative affect decreased and reported positive affect increased significantly across all arms. Improvements showed a dose-response pattern: the 30-minute and 60-minute arms exceeded minimal important difference thresholds for fatigue (change: 30 min=-1.55, 60 min=-1.41, 120 min=-1.19) and positive affect (change: 30 min=1.86, 60 min=1.65, 120 min=1.27), with only the 30-minute arm exceeding the threshold for negative affect (change: 30 min=-1.00, 60 min=-0.92, 120 min=-0.67). In this large-scale, pragmatic intervention, movement breaks demonstrated good implementation potential and effectiveness for improving psychosocial outcomes over the 2-week intervention period. Hourly breaks offered the best balance between feasibility and effectiveness. These findings support movement breaks as a potentially viable public health strategy to reduce the harms of prolonged sedentary behaviour.