# Single Arm Dumbbell Cross Body Crunch

A lying crunch holding one dumbbell, reaching it across the body toward the opposite foot as that leg rises. Trains the abs and obliques one side at a time.

- Intermediate · Compound
- Equipment: Dumbbells
- HD video: https://media.seto.fit/exercises/dumbbell-single-arm-starfish-crunch/video/male.mp4
- HTML: https://seto.fit/exercises/single-arm-dumbbell-cross-body-crunch/

## Muscles worked

- Obliques: 8/10
- Abs: 8/10

## How to do the Single Arm Dumbbell Cross Body Crunch

1. Lie flat, arms and legs spread, a dumbbell in one hand.
2. Lift your torso and reach the dumbbell toward the opposite foot.
3. Raise that leg straight up to meet it.
4. Lower slowly, then switch sides after all reps.

### Full technique — 8 steps

1. Lie on your back with legs straight and arms spread wide on the floor, a dumbbell in one hand.
2. Keep your free hand flat on the floor for support.
3. Press your lower back into the floor and keep your ribs pulled down.
4. Exhale and lift your upper back off the floor, reaching the dumbbell across your body toward the opposite foot.
5. At the same time, raise the opposite leg straight up until it is close to vertical.
6. Keep the other leg long and low on the floor.
7. Lower your arm, torso, and leg back to the floor under control.
8. Complete all reps on one side, then switch arms.

## Common mistakes

- Swinging the leg with momentum
- Swinging arms for momentum
- Bending knees to shorten range
- Dropping into the next rep

## Form cues

- Exhale into the crunch
- Reach toward your toes
- Lift with abs first
- Keep knees straight

## How much to do

- **Strength**: 3–4 sets of 8–10 reps · rest 1 min 15 s · 2 reps in reserve · lower 2 s, lift 1 s, pause 1 s
- **Muscle growth** (good fit): 3–4 sets of 10–15 reps · rest 1 min · 2–3 reps in reserve · lower 2 s, lift 2 s
- **Endurance** (good fit): 2–3 sets of 15–20 reps · rest 45 s · 3–4 reps in reserve · lower 2 s, lift 2 s

Reps in reserve: how many more you could still do when you end the set.

## Substitutes by equipment

Same muscles, same movement — pick the version you have the gear for.

- **Medicine ball**: [Half Kneeling Medicine Ball Woodchop](https://seto.fit/exercises/half-kneeling-medicine-ball-woodchop/)
- **Barbell**: [Tall Kneeling Landmine Rotation](https://seto.fit/exercises/tall-kneeling-landmine-rotation/)

## Where to start and where to go next

Same muscles, same movement. Too hard for now — step down; once it gets easy — step up.

- Easier: [Tall Kneeling Dumbbell Woodchop](https://seto.fit/exercises/tall-kneeling-dumbbell-woodchop/) — Beginner
- Easier: [Half Kneeling Dumbbell Low-to-High Woodchop](https://seto.fit/exercises/half-kneeling-dumbbell-low-to-high-woodchop/) — Beginner
- **This exercise: Single Arm Dumbbell Cross Body Crunch — Intermediate**
- Harder: [Side Plank Reach Through](https://seto.fit/exercises/side-plank-reach-through/) — 45% of bodyweight

## Quick answers

### What muscles does the Single Arm Dumbbell Cross Body Crunch work?

Primary: Obliques 8/10, Abs 8/10.

### When should I do the Single Arm Dumbbell Cross Body Crunch in a workout?

Finisher. Goes last, once the heavy work is done. ≈ 7 min with rest.

### How many sets and reps of the Single Arm Dumbbell Cross Body Crunch?

Strength: 3–4 sets of 8–10 reps, rest 1 min 15 s, 2 reps in reserve. Muscle growth: 3–4 sets of 10–15 reps, rest 1 min, 2–3 reps in reserve. Endurance: 2–3 sets of 15–20 reps, rest 45 s, 3–4 reps in reserve.

### What can I do instead of the Single Arm Dumbbell Cross Body Crunch?

Medicine ball: Half Kneeling Medicine Ball Woodchop. Barbell: Tall Kneeling Landmine Rotation.

### What is an easier version of the Single Arm Dumbbell Cross Body Crunch?

Half Kneeling Dumbbell Low-to-High Woodchop (Beginner), Tall Kneeling Dumbbell Woodchop (Beginner).

### What is a harder version of the Single Arm Dumbbell Cross Body Crunch?

Side Plank Reach Through (45% of bodyweight).

How we rate exercises: https://seto.fit/guides/methodology/

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