Try this workout if you want to build ab strength and endurance. It contains
various strength and isometric movements to help build a stable core. The
circuit is 8 exercises back to back, 4 reps each and 10 seconds of rest between
each round.
Workout available in the Gymaholic Training
App: https://www.gymaholic.co/training/workouts/397400/ab-finisher-home-workout