For your abs
For your abs, the two are close. Ab wheel rollout rates slightly higher: more stretch.
Decline sit-up is easier to progress.
Both are good choices, and they train the abs differently. Using both across your week covers more of the muscle than either alone: in studies, varied exercises grew parts of a muscle that one exercise missed. (Fonseca et al., 2014; Costa et al., 2021)
The research score comes from these, scored by hand from the studies. Lifter scores appear once an exercise has 10 ratings. How scores work
Ab Wheel Rollout. Hard work for the abs in a stretched position, but difficult to progress and tough on the lower back if form slips.
For your abs, the two are close. Ab wheel rollout rates slightly higher: more stretch. Decline sit-up is easier to progress. Both are good choices, and they train the abs differently. Using both across your week covers more of the muscle than either alone: in studies, varied exercises grew parts of a muscle that one exercise missed.
Decline sit-up is easier: it’s easy to learn, while ab wheel rollout takes some practice.
Ab wheel rollout needs no equipment, so you can do it anywhere. Decline sit-up needs a bench, so a home gym covers it.
Decline sit-up: it rates Strong for joint and recovery cost in our research rubric, against Good for ab wheel rollout.