Rectus abdominis activity occurs during which two general portions of the gait cycle?

Rectus abdominis activity occurs during which two general portions of the gait cycle?

• A. 0-10% and 50-60%
• B. 10-20% and 40-50%
• C. 20-40% and 70-90%
• D. 40-60% and 90-100%

Answer: (C)

Rectus abdominis helps stabilize the trunk and control forward lean during walking, so its activation is most beneficial in two key windows of the gait cycle. In the early part of stance, roughly 20–40% of the cycle, the body weight loads onto the leg and the pelvis tends to tilt forward while the spine can extend due to momentum. A contraction of the rectus abdominis counters this tendency, pulling the rib cage toward the pelvis to maintain a neutral spine and stable trunk as weight is accepted. Later in the cycle, about 70–90%, the leg is swinging forward and the body must brace in preparation for heel contact. The rectus abdominis again activates to stabilize the trunk and pelvis as forward momentum is controlled. These two periods—early stance and late swing—are when this muscle most helpfully contributes to maintaining posture and stability during gait.

Rectus abdominis helps stabilize the trunk and control forward lean during walking, so its activation is most beneficial in two key windows of the gait cycle. In the early part of stance, roughly 20–40% of the cycle, the body weight loads onto the leg and the pelvis tends to tilt forward while the spine can extend due to momentum. A contraction of the rectus abdominis counters this tendency, pulling the rib cage toward the pelvis to maintain a neutral spine and stable trunk as weight is accepted. Later in the cycle, about 70–90%, the leg is swinging forward and the body must brace in preparation for heel contact. The rectus abdominis again activates to stabilize the trunk and pelvis as forward momentum is controlled. These two periods—early stance and late swing—are when this muscle most helpfully contributes to maintaining posture and stability during gait.