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?
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That powerful connection between exercise and teens' brain development
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ALLOWS A VARIETY OF EXERCISES - This sit up mat by DMoose is great for doing crunches, sit-ups, leg lifts, or even just lying down for a good relaxing
DMoose Ab Mat, Sit Pad for Core Workout Training, Full Range of Abdominal and Ab Workouts - Non Slip PVC leather and High-density Foam - Sit Up