This demonstrates active weight bearing hip flexion with spine stability.
In quadruped, with an inflatable exercise ball placed against a wall and against the buttocks, push back into the ball.
Maintain pressure whilst reaching one hand/arm forward. Switch sides. Add neck rotation for variation, or a FMT (tubing) for resistance.
A partner creates resistance at the sacrum, instead of an exercise ball.
Use a FMT (tubing) to create resistance to hip flexion, held in both hands.
Single leg version: express hip extension on one side, rock back into weight bearing hip flexion on the other side, with or without FMT around the foot on the extended leg.
Producing hip flexion with spine stability is important after regaining hip flexion mobility. A common error in squatting, running or kicking, or other split leg tasks, is to produce spine flexion instead of hip flexion.
Common errors and corrections:
The most common error is a loss of spine stability, i.e. rounding of the spine into flexion. The fix is to exaggerate mistake of loss of spine stability with a foam roller on the spine.