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Exercise 101: Sit-Ups

Name of Exercise —Bent knee sit-up

Type of Exercise —Multi-joint

Muscles Used —Abdominals

Starting Position

© 2009 Nucleus Medical Media, Inc.

Upward Movement

Downward Movement

Trainer Tip

It is important to perform a posterior pelvic tilt prior to performing the crunch. To do this, press your lower back into the floor while curling your pelvis slightly upward. This will engage your abdominal muscles from the start and make the movement more efficient. Place your hands across your chest or down at your sides rather than behind your head.


National Association for Health and Fitness

President's Council on Fitness, Sport & Nutrition


Canadian Society for Exercise Physiology

Health Canada Physical Activity


10 steps to perfect sit-ups. HubPages website. Available at: Updated April 23, 2013. Accessed August 8, 2016.

Bent-knee sit-up/crunches. American Council on Exercise website. Available at: Accessed August 8, 2016.

Last reviewed August 2016 by Michael Woods, MD  Last Updated: 8/8/2016