I was working with a personal training client recovering from low back issues yesterday and I instructed her on the quadraped hip extension exercise. 
This is definitely a favorite of mine which is usually done incorrectly. I instructed the exercise and talked about it’s importance and she revealed that she knew the exercise was good, but did not “feel it” like she would with other exercises making her skeptical. I think that is often a problem as we always want to feel what’s working or have some kind of burning sensation to know it’s effective. In situations like this it is critical to educate the client on why you chose the exercise, what muscles does it work, and what to expect.
To properly execute the quadraped hip extenstion, start in the quadraped position (on all fours- knees under hips, and hands under shoulders). Use a mirror for visual feedback so you can view the entire length of the body from head to toe. Find a neutral spine position and draw in the belly button to lock in this position. Once you have achieved this starting point, extend the hip back as far as you can while maintaining a neutral spine. This is where this exercise goes wrong!! The goal isn’t to get the leg as high as possible but just far enough before you lose a straight spine. Also, make sure you are staying centered and don’t lean over the support leg.
The muscles being working during the quadraped hip extension are 
the spinal extensors including the longissimus, iliocostalis, spinales, and multifidii. Stuart McGill discusses this exercise in detail in his book Low Back Disorders and reveals it causes significantly less lumbar spine compressive forces (<2500N) compared to prone lumbar extension exercises (>6000N), concluding it is safer, especially during low back rehabilitation. Below you will find a video to demonstrate this exercise. Note the use of a broomstick to give feedback on positioning of the spine.
When you say as far back as you can extend the leg until the back begins to lose neutral, do you mean not extending it all the way or not raising it at the end?
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It’s all based on the positioning of the lumbar spine. Go into hip extension as high as you can without the lumbar spine moving into extension. All motion should be focused on the hip while maintaining a neutral spine.
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So some people will be unable to completely extend the leg initially? And are you actively squeezing the glute or just focusing on the movement and have the contraction come from that? Thanks by the way, your blog is pretty solid.
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Everyone will be able to extend the hip but to varying degrees. I have many clients who cannot maintain enough core stability in the beginning, so once they begin extending the hip their lower back arches. But, as we progress and teach proper core stability they are able to extend the hip higher while keeping the lower back locked in a neutral alignment. If you have someone that has difficulty, learning to execute the pelvic tilt first is important. While tilting the pelvis posteriorly and activating the transverse abdominis, the neutral spine position is maintained easier. In the end the key is to teach the body how to do this reflexively and not from a conscious contraction. But yes, extension via the flute maximus is what we want. I instruct people to focus on not just doing the exercise but feeling the glute squeezing while keeping the proper position. Hope this helps. If not let me know and I’ll find a better way to clarify. Thanks.
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Thank you Garrett I will work on that and let you know how it goes. Appreciate your expertise.
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