Sample size estimation

Sample size estimation was performed in a pilot study with the first 20 participants (i.e., 10 participants in each group), which was recommended by Sandvik et al. (1996). In the pilot study, six participants in the reverse-ASLR exercise group (60%) and one participant in the ASLR exercise group (10%) had FMS score improvement to a score of 2 at follow-up 1. G*Power 3 (Faul et al., 2007) estimated that 34 participants (i.e., 17 participants in each group) were required, considering α value of 0.05, β value of 0.2, and proportions of 0.6 and 0.1 in the Fisher exact test. Considering the 20% dropout, 40 patients (i.e., 20 participants in each group) were estimated in the formal study. The methodology did not change after the pilot study; thus, recruitment of additional 20 participants was continued for the formal study.