Sit-Ups, Crunches, Planks, Knee-Ups: The Evolution of Core Fitness Testing

Core strength testing has come a long way from the straight-legged, twisting sit-ups used before World War II.

Crunches Vs. Sit-Ups—Which Exercise Is Better?

Planks or Crunches: Which is Better?

Sit-Ups vs. Crunches

The Major Differences Between Sit-Ups and Crunches

Core Training. Suppose you want to tone your abdominal…

Mastering Functional Core Workouts for Peak Performance

Are Sit-Ups Bad for You? Sit-Ups vs Crunches vs Planks

5 Easy Ways to Test Core Strength - wikiHow

Forget sit-ups — 10 best crunches and variations to…

Hover Exercise vs Plank vs Crunch - Ab Workouts