While ascending stairs, an elderly patient leans forward with increased hip flexion. Which muscle is BEST utilized in this forward posture?

While ascending stairs, an elderly patient leans forward with increased hip flexion. Which muscle is BEST utilized in this forward posture?

• A. Rectus femoris
• B. Tensor fascia lata
• C. Gluteus maximus
• D. Lumbar paraspinal

Answer: (C)

When stepping up, propulsion comes mainly from extending the hip to lift the body to the next step. The gluteus maximus is the primary hip extensor, so it provides the main force to rise, even when the trunk is leaned forward. This forward posture shifts the demand away from the knee and toward hip extension, which is why this muscle is activated to drive the ascent. The other muscles don’t supply that primary hip- extension power: the rectus femoris mainly flexes the hip and extends the knee, which would oppose the upward push; the tensor fascia lata assists with hip flexion and pelvic stabilization rather than producing the big hip-extensor thrust needed for ascent; and the lumbar paraspinals mostly stabilize the spine and posture rather than generating the primary propulsion to lift the body to the next step.

When stepping up, propulsion comes mainly from extending the hip to lift the body to the next step. The gluteus maximus is the primary hip extensor, so it provides the main force to rise, even when the trunk is leaned forward. This forward posture shifts the demand away from the knee and toward hip extension, which is why this muscle is activated to drive the ascent.

The other muscles don’t supply that primary hip- extension power: the rectus femoris mainly flexes the hip and extends the knee, which would oppose the upward push; the tensor fascia lata assists with hip flexion and pelvic stabilization rather than producing the big hip-extensor thrust needed for ascent; and the lumbar paraspinals mostly stabilize the spine and posture rather than generating the primary propulsion to lift the body to the next step.