The cause of a wide lead-leg swing and flat foot plant is best described as weakness in which areas?

• A. Trunk and thigh muscles.
• B. Calf and foot intrinsic muscles.
• C. Gluteus maximus only.
• D. Forearm muscles.

Answer: (A)

A stable pelvis and controlled leg swing rely heavily on core (trunk) strength and the thigh/hip muscles. When this proximal strength is lacking, the pelvis can’t stay level or align the hip and knee properly during the swing, so the lead leg tends to swing outward in a wider arc. That uncontrolled path makes it harder to set up a precise, quick foot contact, often resulting in the foot landing flatter rather than in a efficient, plantarflexed strike. In other words, weak trunk and thigh muscles disrupt pelvic stability and leg alignment, producing the wide lead-leg swing and flat foot plant.

Calf and intrinsic foot muscles mainly affect the push-off and foot stability at contact, not the overall swing path and landing alignment to the same degree. Forearm muscles have no meaningful role in sprint mechanics.