Introduction: Analyzing muscular co-contraction activity can help clinicians assess mechanical and motor control changes in individuals with pronated feet (PF) during rehabilitation. This study examines the impact of double-density foot orthoses (FO) on muscular co-contraction activity in adults with PF during running at a constant speed, compared with healthy controls.
Method: Twenty male adults with PF and twenty healthy male controls volunteered for this study. Muscle activity was recorded using an electromyography system (Biometric Ltd, UK). We measured two variables, directed co-contraction and general co-contraction, while participants ran along an 18-meter walkway, both with and without foot orthoses.
Result: We found lower general knee co-contraction (p=0.017; ƞ2=0.241) during the loading phase (especially in the PF group) when running with FO than without. We observed decreased directed knee flexor/extensor co-contraction during mid-stance in the PF group when running with FO compared with running without it (p=0.040; ƞ²=0.185). This effect was not seen in the healthy group. Additionally, we found greater directed ankle co-contraction during the push-off phase in the PF group when running with FO compared with without (p=0.006; ƞ²=0.305), which was also not observed in the healthy group.
Conclusion: These findings suggest that FO use significantly reduces co-contraction during running, enhancing biomechanical efficiency and potentially mitigating the risk of joint dysfunction and related injuries. FO appears to improve movement mechanics, supporting better alignment and function in individuals with PF.