Correct technique for ab wheel rollout or must the hip flexors work isometrically?

Question

I see two slightly distinct ways to do kneeling ab wheel rollouts.

1. Hip does not bend, hip flexors are worked isometrically only, movement extends only as far as this is doable. As seen in this youtube viseo and on exrx

2. Highly similiar to the first in the outward part of the movement, but the guy actually advises to slightly crunch in the inward part. As seen here.

My observation is that when extending too far, I cannot do the backward portion without a slight, active tuck from the abs. For me, as I have lower back problems, I will do the first version and probably use a door or something to limit range of movement to something managable. Better safe than sorry and all that.

Ultimately, which version is safer, which is more effective and why?

Answer 1

I'm not sure what you mean by a tuck from the abs but you will inevitably have to crunch more the further you roll out. That said, the crunch shouldn't come at the expense of a straight back. When I first started with the ab-wheel I had very poor form and routinely let my back sag once I got above 3 or 4 reps.

My coach was able to correct this by teaching me proper breathing for this movement (breathe in while rolling out and breathe out while rolling in). This forces you to keep your back straight. I was instructed to always move the hip forward first (thus keeping the wheel under the chest) until the movement naturally drives the arms forward in order to keep the back straight. The movement is thus what was demonstrated in the first video you linked.