Muscles are classified on the basis of the functions as well, right? Can someone give examples for the natural body movements in which Abs work as Agonist to produce isolated lumbar flexion (except Ab crunches)?

As far as my knowledge and analysis goes, I am seeing the Abs working as ‘Stabilizer’ only in various movements.

Well, ab flexion occurs in some movements.. Usually if you chop some wood for example, there will be some ab flexion.

The abs work in rotational movements like throwing too (though not lumbar flexion)

good answer Karky.

Do we have to train those limited lumbar flexion and rotational tasks(predominantly in the thoracic column) of Abs in supine lying posture? A lot many lay persons and fitness trainers believe that Abs can’t be trained in standing and the ultimate exercises are Ab crunches and leg raises done in supine lying. I have noticed a majority of exercisers struggle to control the lumbar lordosis during that first few degrees of elevation of legs where the gravitational torque will be maximum, although that’s the angle at which Abs must play a vital role.

Oblique abdominals produces trunk rotations along with the actions of its antagonists (spinal rotators located in the back)- force couple mechanics in the transverse plane?. When agonist and antagonists are working conjointly in a given time, to produce the same action , i think still there is vital stabilizer function performed by Abs to create a working foundation.