Using the Precor Ab Flexion machine with body supine, hand on handles
and feet anchored in foot locks: heavy reisistance at 30 to 35 lbs and
fast short arc repetitions of about 10 to 15 degrees.
Care taken to avoid neck compression and cheating with forward head
action or cervical flexion.
Short arc ab flexion is supposed to be a primary action of rectus
abdominis; however, lower obliques near iliac crests seem to be sore
from this exercise.
— mb