Statistical and subgroup analyses
The sample size determination has been previously published [Quantitative variables are expressed as mean (standard deviation). Qualitative variables are expressed as number and percentage. The study group characteristics before the intervention were compared using unpaired t-test (quantitative) and Fisher’s exact test (qualitative). The overall effect of physical activity prescription was compared between the verbal and prescription groups using linear mixed-effects models, to correlate observations on an individual level (different time points) and a centre level (different patients in the same medical centre) over three time points (0, 3 and 12 months). The effect of providing a written prescription for physical activity is the group and time interaction coefficient showing the variation between groups for a one-month increase in time. This physical therapy prescription effect will be expressed as a coefficient with 95% CI. This method follows the De Livera, Zaloumis and Simpson recommendations [Analyses were performed using Prism GraphPad 8.0.1 and R 4.2.1. with lmerTest package.