Medicine Ball Crunch
- Primary muscleAbs
- EquipmentMedicine Ball
- DifficultyIntermediate
- TypeCore · Core flexion
- Secondary muscles
- Obliques, Hip Flexors, Serratus Anterior
- Body part
- Core
- Position
- Lying
- Laterality
- Bilateral (both sides together)
- Category
- Strength
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A medicine ball hugged against your chest adds load without changing the crunch's mechanics, and unlike a plate it will not dig into your sternum across a long set. Progression is simply the next ball up; when the heaviest one feels light, move the load overhead or to a cable rather than chasing endless reps.
How to do the Medicine Ball Crunch
- Lie supine with knees bent ~90° and feet hip-width apart; hold the medicine ball against your chest with elbows tucked.
- Posteriorly tilt the pelvis to lightly flatten the low back; brace the abs and keep the neck neutral with a slight chin tuck.
- Exhale and curl the trunk, lifting head, shoulders, and upper back until the shoulder blades just clear the floor; keep the ball touching your chest.
- Pause briefly and squeeze the abs; do not pull with the arms or jut the chin forward.
- Inhale and lower slowly, placing the spine back down segment by segment until the shoulder blades touch.
- Maintain a small, controlled range and steady tension; stop if you feel low-back discomfort or hip flexor dominance.
Tip: Breathe out as you crunch and let the last bit of air leave the lungs at the top of each rep.
Muscles worked
Primary
Abs · Core
The rectus abdominis shortens to bend the spine forward, and each rep should end with the upper abs fully contracted and the ribs pulled down.
Secondary
- Obliques — Twisting or side crunch variations bring the obliques in, and you should feel them along the side of the waist on the working side.
- Hip Flexors — The hip flexors take over if your feet are anchored and you come up too high; keep the range short to leave them out.
- Serratus Anterior
Common mistakes
- Pulling on the neck — hands behind the head should support, not yank; keep the elbows wide and the chin about a fist away from the chest.
- Sitting all the way up — a crunch is a curl of the ribs toward the pelvis, not a sit-up; the lower back should stay on the floor the whole time.
- Cranking out fast reps — momentum does the work if you bounce; lift to a squeeze, hold for a count and lower slowly.
- Never adding load — once bodyweight reps get easy, hold a plate on the chest or use a cable rather than doing sets of 50.
Sets, reps and where it fits
| Goal | Sets × reps | Rest |
|---|---|---|
| Strength | 3 × 8–12 | 60 s |
| Endurance | 2–3 × 15–25 | 45 s |
Crunches close out a session after the heavy work, or they can fill the rest periods between sets of a lift that does not need much bracing. Pair a cable crunch with a cable side bend on the same stack.
Variations and alternatives
Similar exercises
Without medicine ball
Frequently asked questions
What muscles does the Medicine Ball Crunch work?
The Medicine Ball Crunch primarily works the abs. It also involves the obliques, hip flexors and serratus anterior, which assist the movement and stabilise the joints.
Is the Medicine Ball Crunch good for beginners?
It is rated intermediate, so it suits people who already train regularly. Beginners can still do the Medicine Ball Crunch with light load and a spotter or coach watching the first few sessions; if it feels awkward, pick an easier variation from the alternatives below first.
What can I do instead of the Medicine Ball Crunch?
If you cannot do the Medicine Ball Crunch, try the Reverse Crunch with Leg Extension, the Decline Crunch or the Arms Overhead Crunch. Each of them trains the abs through a similar movement, so you can swap them in without changing the rest of the workout.
How many sets and reps should I do?
It depends on your goal. For the Medicine Ball Crunch, a sensible starting point is strength: 3 × 8–12 with 60 s rest; endurance: 2–3 × 15–25 with 45 s rest. Train it at the end of a session or pair it with a lower-body lift as active rest.
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