During sprinting acceleration, with the lower leg parallel to the trunk, the thigh of the swing leg is what relative to the trunk?

During sprinting acceleration, with the lower leg parallel to the trunk, the thigh of the swing leg is what relative to the trunk?

• A. Perpendicular
• B. Parallel
• C. Angled forward
• D. Angled backward

Answer: (A)

When sprinting, the limbs move in the sagittal plane and their joints set up predictable angles. If the lower leg is parallel to the trunk, the hip joint is flexed enough that the thigh sits at a near right angle to the trunk. So the thigh is perpendicular to the trunk. This position helps the leg swing through efficiently under the body and sets up the next push-off. If the thigh were angled forward or backward, the angle between the trunk and thigh wouldn’t be a right angle, which doesn’t align with the described leg alignment.

When sprinting, the limbs move in the sagittal plane and their joints set up predictable angles. If the lower leg is parallel to the trunk, the hip joint is flexed enough that the thigh sits at a near right angle to the trunk. So the thigh is perpendicular to the trunk. This position helps the leg swing through efficiently under the body and sets up the next push-off. If the thigh were angled forward or backward, the angle between the trunk and thigh wouldn’t be a right angle, which doesn’t align with the described leg alignment.