For a client with limited hamstring flexibility, what specific adjustment to the range of motion during the Open Leg Rocker best preserves spinal articulation while still challenging core stability?

For a client with limited hamstring flexibility performing the Open Leg Rocker, the specific adjustment to the range of motion that best preserves spinal articulation while still challenging core stability is to reduce the degree of knee extension and leg opening. The Open Leg Rocker is a Pilates exercise where the client balances on the sit bones with legs extended and open, forming a V-shape, then rolls back onto the shoulders and returns to the starting balance. Limited hamstring flexibility means the muscles on the back of the thigh are short and tight, which typically prevents a full leg extension without causing the pelvis to tilt excessively backward (posterior pelvic tilt) or pulling the lumbar spine flat prematurely. When this happens, the spine cannot round smoothly, segment by segment, for the rolling action. Instead, the lower back might flatten into the mat ....