Bodyweight

Sit-Up — CrossFit Technique Guide

BB

By Borja Bes — CrossFit Athlete & Hyrox Finisher

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.

Quick answer

Sit-Up is best used when the workout goal matches its main demand: bodyweight capacity, clean mechanics, and scalable intensity.

Muscles Worked

Rectus abdominisHip flexorsObliques

Equipment

None (AbMat optional)

Best For, Avoid If, and Scaling

Best forBodyweight WODs, skill practice, and athletes who can keep sit-up mechanics consistent under fatigue.
Avoid ifPain changes your movement pattern, fatigue makes reps sloppy, or the workout asks for a standard you cannot repeat safely.
ScalingCrunches, feet-anchored sit-ups, or reduced range of motion.

How to Do the Sit-Up

1

Sit with feet butterflied (soles together), knees out, AbMat under lower back if available.

2

Lay back until shoulders touch the floor, arms reaching overhead.

3

Use the arm swing to initiate the movement — swing arms forward as you sit up.

4

Reach hands forward past the knees at the top — full sit-up position.

5

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).

Related WODs

Use Sit-Up in a Real Workout

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Movement Practice WOD

exercise wod

AMRAP 12

8 controlled reps

10 bodyweight reps

200m easy run or 60 sec cardio

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Technique + Conditioning

scaled workout

4 rounds for quality

10 technique reps

30 sec core hold

12 low-skill conditioning reps

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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.

Build It Into a Workout

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Next Training Tools

Hero WODs with Sit-Up

Related Exercises

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