The end goal for all of us is to be doing real-world “core” exercises.
You’ll get no argument from me on this. But the question becomes:
Is this person physically prepared to do this?
Do they have an optimal core stability strategy?
Or do they use a hip flexor/spinal erector dominant strategy that locks them in extension?
Many would call this an “open” or “scissored” posture, and it’s sub-optimal not only because you’re only using the posterior muscles, but you’re also crushing the back side of your spine (vertebrae and discs) in an effort to create stability.
If this explains you or your athletes, you need to re-build your core stability strategy.
A typical progression would look something like this: click here for link to article: http://robertsontrainingsystems.com/blog/ground-based-core-training/#sthash.LzVxg2kj.dpuf