During terminal stance and pre-swing, the iliopsoas is described as doing what?

During terminal stance and pre-swing, the iliopsoas is described as doing what?

• A. Producing knee extension
• B. Loading like a spring
• C. Going completely inactive
• D. Controlling foot slap

Answer: (B)

During terminal stance and pre-swing the hip is extending as the limb prepares to advance. The iliopsoas is lengthened under control in this phase, which stores elastic energy in the muscle-tendon unit. That stored energy is then released to help drive hip flexion as the limb moves into swing. In other words, the muscle acts like a spring—loading during the late stance and releasing during the transition to swing to aid forward progression. It isn’t primarily producing knee extension, staying completely inactive, or controlling foot slap (those roles involve other muscles and mechanisms).

During terminal stance and pre-swing the hip is extending as the limb prepares to advance. The iliopsoas is lengthened under control in this phase, which stores elastic energy in the muscle-tendon unit. That stored energy is then released to help drive hip flexion as the limb moves into swing. In other words, the muscle acts like a spring—loading during the late stance and releasing during the transition to swing to aid forward progression. It isn’t primarily producing knee extension, staying completely inactive, or controlling foot slap (those roles involve other muscles and mechanisms).