If seat depth is too shallow, what is a common consequence?

• A. Feeling of instability or 'falling out'
• B. Improved thigh and knee support
• C. Increased postural stability
• D. Decreased pressure on ischial tuberosities

Answer: (A)

Seat depth determines how much of the thigh and buttock are supported by the chair. If the depth is too shallow, the posterior thighs don’t have adequate contact with the seat, the pelvis tends to tilt forward, and the base of support becomes unstable. That lack of stable support makes someone feel unsteady and like they might slip out of the chair. Proper depth keeps the thigh surfaces supported and the pelvis in a more neutral position, which helps maintain balance and a secure seated posture. A practical check is to ensure a small clearance behind the knee and enough depth so the back of the thighs are well-supported, with about 2–3 fingers of space behind the popliteal crease.