# Balance Trainer Sit-Up

A sit-up done lying back over a half-dome balance trainer, dome side up, so your back extends over the dome before each rep. Trains the abs through more range than a floor sit-up.

- Beginner · Isolation
- Equipment: Balance Trainer (BOSU)
- HD video: https://media.seto.fit/exercises/crunch-on-bosu-ball/video/male.mp4
- HTML: https://seto.fit/exercises/balance-trainer-sit-up/

## Muscles worked

- Abs: 9/10
- Obliques: 5/10

## How to do the Balance Trainer Sit-Up

1. Lie back over the dome, knees bent, feet flat on the floor.
2. Cross your arms and let your back extend over the dome.
3. Curl your upper body up, lifting slowly, one part at a time.
4. Rise until your torso is upright, then lower slowly back over the dome.

### Full technique — 7 steps

1. Place the balance trainer dome side up and sit on it with knees bent and feet flat on the floor.
2. Lie back until the dome supports your lower back and hips.
3. Cross your arms over your chest and let your upper back extend over the dome.
4. Exhale and curl your torso upward, lifting one vertebra at a time off the dome.
5. Continue until your torso reaches an upright position over your hips.
6. Lower yourself back down under control until your upper back extends over the dome again.
7. Keep your feet planted and your hips still on the dome throughout.

## Common mistakes

- Yanking the head forward
- Feet lifting off the floor
- Dropping back without control
- Stopping at a crunch
- Hips sliding off the dome

## Form cues

- Lead with your ribs
- Keep feet planted
- Exhale on the curl
- Curl, don't yank up

## How much to do

- **Strength**: 3 sets of 8–12 reps · rest 1 min · 2 reps in reserve · lower 2 s, lift 1 s
- **Muscle growth** (good fit): 3–4 sets of 10–15 reps · rest 1 min · 2–3 reps in reserve · lower 3 s, lift 1 s, pause 1 s
- **Endurance** (good fit): 2–3 sets of 15–25 reps · rest 45 s · 3–4 reps in reserve · lower 2 s, lift 1 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.

- **Dumbbells**: [Dumbbell Decline Sit-Up](https://seto.fit/exercises/dumbbell-decline-sit-up/), [Dumbbell Straight Arm Crunch](https://seto.fit/exercises/dumbbell-straight-arm-crunch/)
- **Resistance bands**: [Lying Resistance Band Crunch](https://seto.fit/exercises/lying-resistance-band-crunch/), [Lying Resistance Band Knee Tuck](https://seto.fit/exercises/lying-resistance-band-knee-tuck/)
- **Medicine ball**: [Medicine Ball Toe Touch Crunch](https://seto.fit/exercises/medicine-ball-toe-touch-crunch/), [Medicine Ball Straight Arm Crunch](https://seto.fit/exercises/medicine-ball-straight-arm-crunch/)
- **Suspension trainer**: [Suspension Trainer Hanging Knee Raise](https://seto.fit/exercises/suspension-trainer-hanging-knee-raise/), [Suspension Trainer Hanging Leg Raise](https://seto.fit/exercises/suspension-trainer-hanging-leg-raise/)

## 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: [Ab Wheel Straight Arm Crunch](https://seto.fit/exercises/ab-wheel-straight-arm-crunch/) — 15% of bodyweight
- Easier: [Reverse Crunch](https://seto.fit/exercises/reverse-crunch/) — 25% of bodyweight
- **This exercise: Balance Trainer Sit-Up — 30% of bodyweight**
- Harder: [Ab Wheel Half Rollout](https://seto.fit/exercises/ab-wheel-half-rollout/) — 40% of bodyweight
- Harder: [Ab Wheel Knee Tuck](https://seto.fit/exercises/ab-wheel-knee-tuck/) — 60% of bodyweight

## Quick answers

### What muscles does the Balance Trainer Sit-Up work?

Primary: Abs 9/10. Also works: Obliques 5/10.

### When should I do the Balance Trainer Sit-Up in a workout?

Finisher. Goes last, once the heavy work is done. ≈ 6 min with rest.

### How many sets and reps of the Balance Trainer Sit-Up?

Strength: 3 sets of 8–12 reps, rest 1 min, 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 15–25 reps, rest 45 s, 3–4 reps in reserve.

### What can I do instead of the Balance Trainer Sit-Up?

Dumbbells: Dumbbell Decline Sit-Up, Dumbbell Straight Arm Crunch. Resistance bands: Lying Resistance Band Crunch, Lying Resistance Band Knee Tuck. Medicine ball: Medicine Ball Toe Touch Crunch, Medicine Ball Straight Arm Crunch. Suspension trainer: Suspension Trainer Hanging Knee Raise, Suspension Trainer Hanging Leg Raise.

### What is an easier version of the Balance Trainer Sit-Up?

Reverse Crunch (25% of bodyweight), Ab Wheel Straight Arm Crunch (15% of bodyweight).

### What is a harder version of the Balance Trainer Sit-Up?

Ab Wheel Half Rollout (40% of bodyweight), Ab Wheel Knee Tuck (60% of bodyweight).

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

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