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

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

Hold on a Minute: 3 Dilemmas in Our Understanding of Core Stability

Are Sit-Ups or Crunches Better? - SET FOR SET

25 Hanging Ab Exercises for a Chiselled Six Pack and Iron Strong Core

Planks or Sit-ups for Sports Performance? — CoachMrFoster

5 Essential Core Exercises

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Come plank! It engages more muscles than crunches or sit ups. Plus it burns more calories!!

Fitness

The Difference Between Sit-Ups and Crunches—and How to Do Them Correctly

The Best Sit-Up Variations for a Strong Core