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A simple guide to what your core is and how to safely increase core strength without increasing back pain

The “core” of our bodies is regularly caught up in an amazing conglomerate of fitness fads (I love using “conglomerate” anywhere possible). Core may have become a word you hear so often you almost can’t even say it and likely don’t fully understand what it means.

Time to bring some clarity to the topic of our core. You should keep reading this article if you want to learn:

  • What the“core” is and what muscles are the key players
  • Why the core is so important
  • Effective ways to coordinate and strengthen your core
  • Ineffective and pain provoking core exercises you should avoid (even if you see other people doing these in the gym)

The core and the muscles that make up the core

To be plain, our core refers to all of the structures that attach to and keep our trunk stable. Abs, hips, shoulders, back, etc…they all play a part.

Let’s narrow our focus and just get to know the muscles of our core that immediately surround our trunk and lumbar spine:

  • Transverse abdominis, internal oblique, external oblique, rectus abdominis. These muscles are stacked on top of each other and together are generally referred to as your abs. They act as an internal belt or old-school corset to stabilize your spine.
  • Diaphragm. Yes, that muscle that moves our lungs and helps us breathe is actually a key stabilizer of our spine. Contraction of the diaphragm alone can produce up to a 30% increase in lumbar spine stability.
  • Pelvic floor muscles. This group of muscles basically forms a bowl shape at the bottom of our trunk and plays many crucial roles including stability of our trunk.
  • Multifidus, erector spinae, quadratus lumborum (QL). There is an impressively large gang of small muscles in your back that are critical to our spine stability. These are just a few of the major players. 

Why our core is important

  1. Spine stability
  2. Power transfer
  3. Foundation for power production and control

I said enough in my previous article about spine stability to leave it alone here. But the implications for back pain are huge.

All three in this list are very interrelated, but numbers 2 and 3 are especially so. When I say power, your mind might turn automatically to sports, but we humans need to produce power all the time. Let’s look at just one example of how this works.

Have you ever tried to cooly walk out of a store, only to find yourself struggling to push open the door? Pretty embarrassing right? You find yourself trying to squeeze your way out through that little gap you were able to make. 

There it is…the enemy push door with the sticky hinges

Now maybe the door just caught you off guard, or maybe they haven’t greased those hinges in a decade. The fact is, you didn’t produce enough power to fully open the door and make a smooth escape.

Our core needs to activate to stabilize our trunk, which will then allow for a transfer of power from our legs to our arms (#2). Our core muscle complex also needs to activate to create a solid foundation for our arms to push from (#3). Without a stable core, power from our legs leaks out of our system and our arms are pushing from a wobbly foundation = sticky old door wins.

Improve the strength and coordination of your core muscles

I know everyone wants a list of exercises in this section. What’s more important are the principles, but I’ll succumb and give a few examples to clarify the principles.

Your core should be stubborn and immovable…this dog is your role model

The most important principle to understand is simply this: your core is designed for stability (I know I already said this). This means your core muscles are best for resisting trunk flexion, extension, side bending and rotating. Resisting! (In the gym you likely see people doing the opposite of this repetitively, but I’ll save my expounding on this for the next section.)

Think of your core as extremely stubborn. You want this system to be immovable to external forces. 

Here are some practical examples of what I mean, and remember these are just examples of core exercises I like. I’m not saying that these exercises are king or the only way it can be done or that they will get you out of pain.

  • Resisting trunk flexion/extension: fallouts. This can be done an assortment of ways using suspension trainers (shown below), an ab wheel, with your arms on an exercise ball, or with socks under your hands on a slick floor. What matters: keep a neutral spine. Don’t let it flex or extend during the movement.
Fallouts with a suspension trainer
  • Resisting trunk rotation: pallof press. This can also be done in several ways, but below is a good example. Just set up a band or cable perpendicular to your body, then extend your arms and bring them back in towards your chest without letting your trunk rotate.
Pallof press
  • Resisting trunk side bending: one-arm farmer carries. You can do this with a dumbbell, kettlebell, or really anything you can grip. This exercise is a major winner in my book. It’s basically a standing/walking version of a side plank. It’s also incredible for your grip, shoulders, hips…basically your whole body. 
One-arm farmer carry: pick up something heavy and walk

Brick masons often carry their bricks in this style. Have you ever tried to shake the hand of a man who has been a brick mason his whole life? I have, and I thought my hand might never recover. That man is so powerful and immovable, sticky doors somehow become automatic doors for him.

Ineffective core exercises that increase risk of back pain

Again, the principles here are what is important, and it’s basically the opposite of what we just discussed. Poor core exercises that put your spine at increased risk for injury involve performing trunk flexion, extension, side bending, and rotation repeatedly and/or under load. 

The following examples are for clarification. There are plenty of other risky exercises out there, but these are just my favorite ones to pick on:

  • Trunk flexion: traditional sit-ups, and any other form of spine curling under load and/or repetition. 
  • Trunk extension: hyperextensions. Now, this movement can be performed correctly, but that’s something I see rarely. The risk vs. reward isn’t favorable here, so best to just avoid it altogether.
  • Trunk side bending: standing side bends with weights in your hands. This activity looks awkward, has no purpose, and your spine doesn’t love it either. Stay far away.
If you get nothing else from this article: don’t do these
  • Trunk rotation: russian twists. Unnecessary. Risk vs. reward again not favorable.

You may be really disappointed to find an exercise you like on my list, and you may just disregard my thoughts because of it. But think about what your goals are. Why are you doing that exercise in the first place?

Is your ultimate goal really to do 100 weighted side bends in a minute, or is to feel healthy and energized, look your best, and stay active as long as you can? Gym fads and fitness salespeople try to sell you on the process, but the results are what matters. 

I obviously don’t know what results you want, but I’m sure one of them doesn’t include back pain. I’m also confident you can get those results doing safer exercises following the sound principles we discussed earlier.


This article is a bit different than my usual treading. I am a physical therapist and my focus is diagnosing and treating specific pain generators. I like to leave the offering of specific exercises for coaches and trainers. But I find the principles of core training so misunderstood, leading to much back pain and grief, that this article felt necessary.

Please don’t do something in the gym just because the ripped guy next to you is doing it, because he might also be ripping up his back pain. Remember the principles, not just the exercises, and you can do all of this at home or in an extravagant gym. 

The purpose of this article is to save you from unnecessary risk to back injury and pain. And to prepare you to attack those sticky doors with confidence!