Which muscle should be engaged to prevent excessive hip/trunk extension during rowing exercises?

The rectus abdominis is crucial for maintaining stability and controlling the alignment of the pelvis and spine during rowing exercises. Engaging this muscle helps to prevent excessive extension of the hips and trunk, which can compromise form and lead to injury. The rectus abdominis provides anterior support and helps to stabilize the core, allowing for effective force transfer from the lower to the upper body while rowing. By keeping the trunk in a neutral position, the rectus abdominis helps ensure proper mechanics throughout the exercise, enhancing performance and safety.

Other muscles may play roles in stability and movement during rowing, but the rectus abdominis specifically addresses the need to maintain a controlled posture against excessive extension, making it the most suitable choice in this context.