Final answer:
The gluteus medius is most active during the stance phase of walking, playing a crucial role in stabilizing the pelvis and abducting the femur at the hip for balance.
Step-by-step explanation:
The gluteus medius muscle is most active during the stance phase of walking. This muscle is located deep to the gluteus maximus and is one of the gluteal muscles responsible for stabilizing the pelvis and controlling the movement of the femur. Specifically, the gluteus medius is crucial for the abduction of the femur at the hip, and it plays a pivotal role during the stance phase when one foot is on the ground, providing stability and balance to the body