the effect of sand exercise program on knee muscle co-contraction in runners with over-pronated feet during running

Purpose: over-pronated foot (opf) is a common abnormality of the foot. sand can change lower limb muscle activities. therefore, the aim of this study was to evaluate the effect of a sand exercise program on knee muscle co-contraction in runners with opf. methods: thirty individuals (age range: 18–26 years) with opf were randomly allocated to the equally sized control and experimental groups. the experimental group performed a sand running exercise protocol for eight weeks. muscle activities were recorded using an electromyography system. two variables, including directed co-contraction and general co-contraction, were calculated before and after training programs. results: in the experimental group, lower directed vastus lateralis/vastus medialis co-contraction, greater general knee co-contraction, and directed medial/lateral knee co-contraction during the mid-stance and push-off phases were found at the post-test compared to the pre-test (p<0.017). irrespective of the time, greater directed medial/lateral knee co-contraction during the push-off phase was observed in the experimental group (p=0.043). conclusion: sand can be used as a suitable surface for training, as increased muscle co-activation is required to make postural adjustments during running.