effect of overweight and fatigue on ankle directed and general co-contraction during running

Purpose: it is uncertain how fatigue protocol and overweight affect electromyography (emg) activity of lower limb muscles. the purpose of this research was to evaluate how excessive body weight and fatigue influence the co-contraction of the ankle joint during running. methods: forty-eight females were divided into four groups. the first group consisted of individuals with a body mass index (bmi) of less than 25 kg/m² and normal foot (navicular drop: 4 to 10 mm). the second group consisted of individuals who had a bmi within the normal range (bmi <25 kg/m²) and had feet that rolled inward (a navicular drop of more than 10 mm). the third group included individuals who had a bmi of 25 kg/m² or higher and normal feet (navicular drop: 4 to 10 mm). the fourth group included individuals with a bmi of 25 kg/m² or higher and flat feet (navicular drop: more than 10 mm). the running task was done at approximately 3.2 m/s over an 18-meter distance before and after the fatigue protocol. the walkway had a force plate embedded at its midpoint. activity from the tibialis anterior, gastrocnemius medialis, vastus lateralis (vl), vastus medialis (vm), rectus femoris (rf), biceps femoris (bf) and semi tendinosus (st) were collected using a surface bipolar emg system. results: the results demonstrated significant main effects of “group” for general ankle co-contraction during the loading phase. pairwise comparisons demonstrated significantly greater general ankle co-contraction ​​in the overweight/normal foot group compared to the other groups. conclusion: the general ankle co-contraction values were higher in the overweight groups than in the normal groups, which can be associated with overloads on the ankle joint. these findings can be useful for designing rehabilitation protocols for overweight people with and without pronated feet.