Thank you! I’m glad you found the info useful.

Yea, lumbar disk injuries are very common and the pain is debilitating. My Dad has had lumbar surgery, so, I'm aware of the suffering.

Yes, the plank exercises the core isometrically, the way it is supposed to be.

I plan to show the various ways to exercise the ’core’ tomorrow. Stay tuned for that:) there will be more exciting moves than the plank included there ;)