If you were to ask anyone who participates in my group fitness classes or does personal training with me what are the top 3 phrases I use, one them would certainly be “engage your core!”

We hear a lot of talk about the core, but what exactly is it and why is it so important? The core is made up of the muscles surrounding your mid-section (sometimes called trunk); it includes the abdominals, obliques, diaphragm, pelvic floor, trunk extensors, and hip flexors. Some people define it as the area between the mid-thigh to just below the pectoral muscles.

The core important because it provides stability for doing many of the tasks of daily living, and supports everything above it. A weak core can lead to overloading other muscles, which often leads to back pain. Most of the activities in which we engage–both in the gym and out–depend on us having a core that is strong enough to support the movements required.

When I say, “engage your core,” what does that mean? I usually follow this term with the instruction to keep shoulders back, chest up, and belly button pulled back to the spine. This is an oversimplification, but it is a signal to my clients that they need to be aware of their posture. I often tell them to imagine the drill sargeant is about to come by and they need to stand at attention.

There are a number of exercises that help to strengthen the core. A popular one is doing abdominal braces. Basically, this involves tightening the muscles of the mid-section all at once. Imagine that someone is about to punch you in the gut; what muscles would you tighten to lessen the impact of the punch? This is what you do in a bracing exercise. There are all kinds of bracing exercises, many of which you can find with explanatory videos by using a simple internet search. Doing these exercises will give you a good idea of just how strong your core is (or isn’t!).

Other exercises to help strengthen the core include: Ab crunches, glute bridges, bird dogs, planks, side planks, and superheroes (formerly known as supermans). None of these exercise requires any kind of equipment; they can be done at home on a mat or other soft, but sturdy surface. If you want to make use of dumbbells you can add in: deadlifts, russian twists, wood chops (that also work the arms and shoulders), and over/unders. At the gym, there are machines that will also work the core and allow for varying the amount of resistance being used; ask a trainer or other employee to show you which machines they are and how to use them.

Getting to the core of the matter is an essential part of any exercise regimen. Lots of people like to focus on upper body and arms, as well as legs, but often leave out core. This is like building a home but leaving out the foundation. You cannot build a strong body without a strong core to support it all. Next time you are exercising, I hope you imagine me reminding you to “engage your core!”