Crunches

How to do it

1. Lie on your back with your knees bent and your feet flat, heels about a foot from your hips.
2. Place your hands behind your head with the elbows open, or cross the arms on the chest.
3. Press the lower back gently into the floor and brace the abdominals.
4. Exhale and curl the rib cage toward the pelvis until the shoulder blades lift off the mat.
5. Pause with the lumbar spine still in contact with the floor.
6. Inhale and lower under control without dropping the head between reps.

Common mistakes

• Yanking on the head with the hands, which strains the neck and fakes trunk range.
• Curling all the way to a sit-up, which hands the work to the hip flexors.
• Lifting the lower back off the floor, which turns a short curl into a swing.
• Racing the reps so the abdominals never stay shortened at the top.