Group Fitness Instructor

Answer: A - Group Fitness Instructors who choose to use closed chain exercises during their sessions are taking advantage of the fact that a closed-chain exercise tends to produce joint compression instead of shear. Consider the squat versus the (open chain) seated knee extension. In the open chain knee extension exercise, as the foot moves forward in space pulled by the quadriceps, the tibia tends to shear or translate forward on the femur, producing joint stress. In contrast, during a squat, the contraction of the quadriceps is balanced by a protective contraction of the hamstrings and the tibia does translate forward during the movement.