Statistical methods
REGRESSION
Analysis was performed using STATA version 17.0 (StataCorp LP, College Station, Texas, USA). Participant characteristics of each group were presented as means and standard deviations (SD) for continuous variables and as percentages and frequencies for categorical variables. Physical activity outcomes at baseline and follow-up were presented as medians and interquartile ranges (IQR). Two analyses were performed: all participants that completed T1 baseline physical activity assessment were included within the primary analysis (using multiple imputation), while only those that had also completed the 16-week intervention and T2 follow-up assessments were included within the supplementary complete-case analysis. Missing data at follow-up was addressed via multiple imputation using chained equations using fully conditional specification; assuming missing at random 20 imputations were produced. Analysis of change was then performed to compare differences in average daily step count (primary outcome), total self-reported physical activity and transport-related physical activity levels at follow-up between control and intervention groups. Regression analyses were adjusted for baseline values and undertaken on an intention-to-treat basis. Supplementary complete-case analysis, and analysis of change in self-reported leisure-time physical activity, and objective and subjective measures of sedentary levels are presented in Additional file 