long-term exercises on sand improved frequency spectrum of lower limb muscles during running in runners with over-pronated feet

Purpose: pronated feet (pf) are associated with biomechanical changes during running. it seems that sand training can be a suitable intervention for rehabilitation in individuals with over-pronated feet. this study aims to investigate the effect of long-term exercises on the sand on the frequency of lower limb muscles during running in runners with over-pronated feet.methods: the current study was a quasi-experimental type. a total of 29 controls with a mean age of 22.2±2.5 years (control group [cg]) and 30 pronated feet (pf) individuals with a mean age of 22.2±1.9 years (intervention group [ig]) participated in this study. in both pre and post-test phases, participants run barefoot on an 18-m runway at a constant velocity of 3.3±5% m/s while emg activity was recorded using an emg system. the sand training includes barefoot running for 3 sessions per week for 8 weeks. the frequency of lower limb muscle activities was used as a dependent variable. repeated-measures analysis of variance (anova) test was used for statistical analysis.results: the results demonstrated a significant group×time interaction for gluteus medius (gluteus-m) frequency content at the mid-stance phase (p<0.001; η2=0.670). the results demonstrated an increase of frequency content for gluteus-m in cg (but not in ig) at post-test compared to the pre-test. the results demonstrated a significant group×time interaction for medial gastrocnemius (gas-m) frequency content at push-off phase (p=0.049; η2 =0.298). post-hoc analysis demonstrated an increase of gas-m frequency content in ig (but not in the cg) at the post-test compared to the pre-test. conclusion: as mentioned in a previous study, the reduction of gluteus-m frequency content in ig may be associated with reduced foot pronation after sand training. a higher gas-m frequency content in the ig after training may lead to improved force generation during the push-off phase.