Sit-Up — CrossFit Technique Guide
The CrossFit sit-up differs from the traditional gym sit-up: it is typically performed with an AbMat (a small wedge supporting the lower back), feet butterflied out (soles together), and arms swinging overhead at the bottom and reaching forward at the top. This full range of motion engages the abs through their complete length and uses the hip flexors to generate momentum for high-rep efficiency. Sit-ups feature prominently in benchmark workouts like Annie (150 total) and across many Hero WODs as an accessory movement.
Muscles Worked
Equipment
Watch the movement demo
Video tutorial on YouTube — opens in new tab
How to Do the Sit-Up
Sit with feet butterflied (soles together), knees out, AbMat under lower back if available.
Lay back until shoulders touch the floor, arms reaching overhead.
Use the arm swing to initiate the movement — swing arms forward as you sit up.
Reach hands forward past the knees at the top — full sit-up position.
Control the descent back, letting arms swing overhead.
Common Mistakes
Not reaching full lay-back at the bottom — reduces range of motion.
Pulling on the neck — arms should swing, not pull the head forward.
Anchoring feet (e.g. under a rig) in workouts where it is not prescribed — changes the movement stimulus.
Coaching Tips
For fast cycling in WODs, develop a smooth arm-swing rhythm — it drives the movement and reduces muscular effort.
If you lack an AbMat, a folded towel or thin cushion under the lower back works similarly.
Scaling Options
Easier / Beginner
Crunches, feet-anchored sit-ups, or reduced range of motion.
Harder / Advanced
GHD sit-ups (on a glute-ham developer — significantly harder and requires gradual introduction).
Frequently Asked Questions
Why does CrossFit use an AbMat for sit-ups?
The AbMat supports the lumbar spine at the bottom of the movement, allowing the abdominals to work through their full range of motion (from full extension to full flexion). Without support, the lower back lifts off the floor prematurely, shortening the range.
Hero WODs with Sit-Up
Related Exercises
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