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Christine Daecher, DO

The Problem with Sit-ups & Crunches

Updated: Dec 3

I used to be a big fan of crunches and sit-ups. Not anymore!


For this discussion, sit-ups and crunches are synonymous.


Abdominal exercise
The goal is to keep the spine on the floor when doing abdominal exercises. Table top foot taps.


Sit-Ups and the Military


No one knows when people started doing sit-ups, but they are believed to have been around since ancient times. Sit-ups have been part of US military training since the early 1920s. In 2015, the US Army removed sit-ups and crunches from the required fitness skills because these ab moves were found to cause over 50% of soldiers' spine injuries! Throughout the 2010s, all branches of the military phased out every form of sit-ups and crunches.


The problem is that sit-ups result in excessive compressive forces on the lower back, which squeeze the spinal discs. Injury can occur suddenly or slowly over time.


What to do instead...


Despite the media's lukewarm efforts to promote the idea that these moves should not be part of any workout, many of the top YouTube fitness vloggers continue to feed them to their followers. As a physician, I often recommend people use YT videos to get going with working out, but I must always remember to recommend back-sparing ab moves.

Abdominal exercise
Jack knife the arms and legs up and down while keeping the spine on the ground.

There are several moves that I do that involve my spine staying on the mat. At most, I lift my head off. (Video link at the end.)

  • jack-knife - Entire spine on the floor, straight legs, and arms come up and down together.

  • scissors - Entire spine on the floor, legs with pointed toes, scissor up and down as far as hips allow

  • scissors with a beat - Sames as scissors but do a beat with each move (head on or off the floor).

  • wide straddles - Entire spine on the floor, legs and arms straight up with hips flexed straddle to the sides and back to center at the same time.

  • table top foot taps - same position as the hundred (below) except head on the floor, alternating tap one foot to the floor while other leg stays up (top photo).

  • straight leg and arm Swiss Army knife - Similar to dead bugs but arms and legs are straight and the same leg and arm extend. Like scissors up with a strainght arm going overhead. Similar but more difficult than dead bugs.

  • the hundred - This is a Pilates move. Lay on the floor legs in table top position, head off the floor, arms straight and do beats. Inhale on 5 beats and exhale on 5 beats.

  • tuck ups single leg -Entire spine on the floor, single leg and both arms come to the center with bent knees and relaxed arms

  • tuck ups -Entire spine on the floor, legs and arms extend fully and then come to the center with bent knees and relaxed arms.

  • small crossing scissors -Same as small scissors but legs take turns crossing one leg overtop.

  • legs apart, legs together - Entire spine on the floor, legs straight and only a few inches off the floor. Legs straddle apart and together.


About Core Workouts


As long as posture is correct, many core moves that involve planks are safe bets. Standing ab moves are also relatively benign as long as you remember the rule of planes: moving the spine in two or more planes increases your risk of injury. The planes of the spine are flexion and extension (bend forward and bend backward/arching), rotation (twisting from left to right), and side bending (bending sideways). When the spine is moved in two planes, such as bending forward to pick something up while also bending the side to the right, the risk of injury increases greatly due to the force on the discs.


About Stretching and Yoga


The yoga move, half boat, is a fairly back-safe ab move if done properly. The boat or full boat may be safe for most as well, but it is more straining to the back.


Two stretching moves should be avoided. First is the yoga pose, the plow. The plow stretches the posterior longitudinal spinal ligament that runs up and down the back of the vertebral bodies. This ligament should never be stretched in this way, and it is very important for holding the spine and discs in place. Further, the plow causes extreme and unnatural compression to the discs. The other move to avoid is rolling up vertebrae by vertebrae out of a standing toe touch. You are much better off coming up straight or bending your knees first and standing back up. The roll-up does feel like a very good stretch, but again, it is also stretching the posterior longitudinal spinal ligament.



Use this link on Instagram to see my video of all of the ab moves described: https://www.instagram.com/p/C-VoYwwPl59/



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