Two Reasons for Throwing Out Crunches and Sit-Ups

My first reason goes back to the time when a guy named David Marmon hired me to be his graduate assistant. I remember my first day on the job. I wanted to get my workout in. Like a typical meathead, I went out and did some crunches, bench presses, and bicep curls. After my “gettin’ swole” workout, I sat back down in the office expecting some praise and admiration for my superior workout skills. David greeted me with, “Why do you train that way?” I was dumbfounded. I thought I had all the answers when it came to things like getting stronger, fitter, and leaner and all around more awesome. He followed his question with, “We train movements, not muscles.” I guess the idea of training movements, not muscles, kind of stuck with me (even though we still did sit-ups in our programming at the time). Train movements, not muscles.

So taking the train movements, not muscles approach, is bringing your sternum closer to your pelvis a movement you want to get better at? Think about it. When you squat, what are the coaching cues you hear? Chest out. Back flat. Hips back. Right? Same thing with deadlifts and many other exercises. Chest out. Back flat. The spine evolved to handle weight in the “chest out, hips back” position. That’s why we coach it that way. Why would we want to get better in producing force in any other way?

We don’t teach this.

We don’t coach people to get better at being in the rounded back position. So why do they need to get better at it? Your chances for injury are high when you flex the spine. Dr. Stuart McGill has become famous for saying, “Wanna see a disc explode? Keep flexing at the spine.” The torso musculature was meant to transmit force, not produce it.

So we train the limb muscles (ankles, knees, hips, shoulders, elbows, and wrists) to produce force. We train the torso musculature to act as a conduit and transmit force, not produce it. Therefore, the stronger and more rigid we can make the conduit, the more force the body as a whole will be able to produce.

My second reason is that the main function of these muscles is to co-contract. Basically, they contract against one another to stiffen and support the lumbar spine. I call this bracing. This is contrary to the popular belief that people must suck in the stomach to better support the spine (not long ago, I believed this as well). Sucking in actually decreases the stability of the lumbar spine (1).

Ok, so if not crunches and sit-ups, then what? The core is composed of the lumbar spine, quadratus lumborum, muscles of the abdominal wall (rectus abdominus and obliques), back extensors, and multijoint muscles like the latissimus dorsi and the psoas. You could also include the glutes in this group as well because they’re the main power producers and a synergist to the core muscles.

Here at Nunn’s Performance Training, we break our core training into three sections: anti-flexion, anti-rotation, and anti-lateral flexion. The progressions look like this:

Easy → Hard


Quadruped single arm/single leg raise → quadruped opposite arm/leg raise → prone plank → prone plank + weight → stability ball rollout → abdominal wheel rollout → TRX fallout → barbell rollout


Quadruped single arm/single leg raise → quadruped opposite arm/leg raise → Pallof series (half kneeling/high cable, standing/medium cable, standing/low cable)

Anti-lateral flexion*

Quadruped single arm/single leg raise → quadruped opposite arm/leg raise → side plank → side plank + weight → Pallof with overhead press

*We will probably be implementing suitcase deadlifts in the anti-lateral flexion area in the near future.

Here’s a video demonstration:

Core Progressions


  1. Potvin JR and Brown SHM (2005) An equation to calculate individual muscle contributions to joint stability. J Biomech 38:973–980.
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About the Author

Jason Nunn graduated with his bachelor of science degree from Indiana State University in 2005 with a major in exercise science. In December 2006, he finished his master of science degree from Indiana State University with a major in physical education and an emphasis in coaching and nutrition. During college, Jason became a Certified Strength and Conditioning Specialist (CSCS) from the National Strength and Conditioning Association (NSCA). In his spare time, Jason is also a top-level, amateur Strongman competitor. For more information, check out