The Impact of Excessive Muscle Co-Contraction on Sit-To-Stand Performance in High-Heeled Footwear.

This study aimed to analyse the effects of co-contraction on quadriceps and hamstring muscles during sit-to-stand (STS) tasks for females wearing shoes with different heel heights. The study aimed to identify compensatory strategies during the STS tasks in response to excessive muscle co-contraction during high-heeled gait. Sixteen healthy young women (age: 24.4 ± 1.7 years, body mass index: 18.4 ± 1 kg/m, weight: 50.2 ± 5.2 kg, height: 1.63 ± 4.4 m) participated in this study. Electromyography signals were recorded from three quadriceps (vastus medialis, vastus lateralis, and rectus femoris) and one hamstring (semitendinosus) muscles. The participants wore shoes with different heights, including 4, 6, 8, and 10 cm. For each heel height, the co-contraction index is computed to measure postural balance using the quadriceps to hamstring muscle pairs. The results that were obtained and quantified with statistical measures show that for elevated shoes, if co-contraction increases, both quadriceps and hamstring muscles tend to compensate. This suggests that the capacity of the quadriceps and hamstring muscles to compensate is essential to retain normal walking and STS tasks in co-contracted persons. However, the compensation mechanisms may induce imbalance, muscle stiffness, and fatigue for women who regularly use high-heeled shoes during sit-to-stand tasks.