What is the primary muscle group involved in propulsion during gait?

The primary muscle group involved in propulsion during gait is the plantarflexors. These muscles, including the gastrocnemius and soleus, are essential for generating the force necessary to push the body forward during the propulsion phase of walking or running. When the heel lifts off the ground, the plantarflexors contract to extend the ankle, which helps to propel the body forward, contributing significantly to the forward momentum and speed during gait.

In this context, while the quadriceps play a vital role in extending the knee and facilitating stability during stance phase, and the hamstrings assist in controlling the movement of the leg as it swings forward, they are not primarily responsible for propulsion. Hip flexors, including muscles such as the iliopsoas, assist in lifting the leg for the next step but do not directly contribute to the force needed for forward propulsion. Therefore, the plantarflexors are the main drivers of propulsion during gait, making them the correct choice for this question.