Crunch: how to do it, muscles worked and variations
Spinal flexion for abs on the floor, a bench or a machine.
- Main muscles
- Rectus abdominis, Obliques
- Secondary muscles
- Iliopsoas
- Equipment
- BOSU balance trainer, Bodyweight, Stability ball, Resistance band, Medicine ball
- Variations
- 10
All 10 variations
BOSU crunch
Crunch with the lower back resting on a BOSU, which lets you start with the trunk slightly extended and increases the range for the abs.
Form. Sit on the edge of the BOSU and lie back until your lower back rests on the dome with your feet firm on the floor, then flex the trunk bringing your ribs toward your pelvis before lowering with control.
Common mistake. Sitting too high or too low on the dome, pulling on your neck, losing foot contact, or bouncing on the way down.
Starfish crunch
Lying in a star shape, one hand reaches for the opposite foot as the trunk and leg rise together, alternating sides to involve the obliques more.
Form. Lying with your arms and legs spread in a star, raise the opposite arm and leg at once until you touch the foot above your body; lower with control and switch sides.
Common mistake. Bending the knee a lot to reach, pulling on your neck, dropping the arm and leg suddenly, or lifting the lower back off the floor.
Floor crunch
Short trunk flexion lying on your back with knees bent and feet planted, concentrating the work on the rectus abdominis.
Form. Press your lower back into the floor, place your hands beside your head without pulling on it and bring your ribs toward your pelvis until your shoulder blades lift; lower slowly without fully relaxing the abs.
Common mistake. Pulling on your neck with your hands, coming all the way up to sitting like a sit-up, lifting the lower back off the floor, or using momentum to chain reps.
Decline crunch
Crunch on a decline bench.
Form. Flex your ribs toward your pelvis and control the descent.
Common mistake. Coming all the way up by pulling with the hip flexors.
BOSU V-sit crunch
Seated on the dome of a BOSU with your hands on it, you pull your knees to your chest and extend them without putting your feet down, combining abs and balance.
Form. Sit in the center of the dome with your hands at your sides and your feet raised; extend your legs leaning the trunk back and then pull your knees and chest together again while keeping your balance.
Common mistake. Putting your feet down between reps, rounding your back, falling backward, or going faster than your balance allows.
Floor reverse crunch
Reverse crunch lying on the floor that brings the knees toward the chest, slightly lifting the pelvis.
Form. Lie with your knees bent to 90 degrees and your arms at your sides, curl the pelvis bringing your knees toward your chest until the sacrum lifts, and lower slowly without swinging the legs.
Common mistake. Using leg momentum, pushing with the hands, lifting the back too much, or dropping the legs.
Pilates ball crunch
Crunch with a small ball under the lower back that lets you start slightly extended and lengthens the range for the abs.
Form. Place the ball under your lower back, knees bent and hands behind your head; curl your trunk up and return slowly over the ball.
Common mistake. Pulling your head with your hands, coming up with momentum, placing the ball too high, or lifting your feet.
Kneeling banded crunch
Kneeling crunch with a band anchored high and held beside the head, a machine-free alternative to the cable crunch.
Form. Kneel facing the high anchor with the band beside your head, curl the trunk bringing your elbows toward your thighs without sitting on your heels and return with control.
Common mistake. Pulling with the arms, sending the hips back instead of flexing the trunk, arching your back on the way up, or letting go of the band.
Knee-hug crunch
Starting lying down with arms and legs extended, you bring knees and trunk together at once until you hug your knees, working the abs through their full range.
Form. Lying with your arms overhead and legs long, lift your shoulders and feet and pull your knees to your chest, hugging them; extend again without fully resting.
Common mistake. Pulling on your neck, arching your back as you extend, dropping your legs and arms without control, or using momentum.
Under-knee ball pass
Balancing seated with legs raised, you pass a medicine ball under one knee and then the other, working the abs and coordination.
Form. Sit leaning back with your legs raised, bring one knee in, pass the ball under it to the other hand and extend; alternate without putting your feet down.
Common mistake. Rounding your back, putting your feet down between passes, holding your breath, or using a ball that is too heavy.
Other exercises for the same muscles
