Leg Lowering for Core Stability and Strength?

What is your opinion on leg lowering for core stab and strength? Both single leg and double leg?When performed correctly, these moves meet the Joint by Joint approach.  How often these moves are performed correctly is severely in question.The challenge to meet stiffness between the lumbar spine and the hips usually demands extraordinary hip mobility to get this done and get some kind of training effect.  Any movement into flexion or extension of the lumbar spine during these techniques is a mistake.I learned from Wayne Rath several years ago a scoring MMT for the anterior abdominals using the double leg lift and lower.You would put your hand under the individuals back and start in an accepted neutral.A score of 4 is if you perform a full double leg lift up and down.A 3 is all the way up, but then you lose it half way down.A 2 is losing it after half way up, and a 1 if you can't get half way up.I used this a little bit, but it was so long ago where I was still brainwashed into thinking that I had to fill up a PT evaluation sheet with ROM and MMT trivia.  There was also no scoring skew for pain or for how high the legs go up.An interesting key that I see these moves almost more as tests or exhibitions of something very, very positive and valuable, but you probably don't get better by practicing it under a limited environment.[youtube]https://www.youtube.com/watch?v=WXs5HoRPvm0[/youtube]Keep in mind that the ASLR movement-based test has a more lax demand for lumbar spine motion than the exercise-based training choices.You can do a lot better in terms of training, but these moves can be done correctly and can be defended.