What is the "Core"?
Most of us, at one point or another, have suffered through an over-exuberant exercise instructor shouting things like: “belly button to spine!”, “brace your abs!” and “tighten your core!” This is great advice in theory, but many people don’t know which muscles constitute their “core,” or how exactly they should go about “activating” it. Conventional wisdom, in addition to several scientific studies (see references), supports the importance of core training to improve performance and reduce the risk of injury. Clinically, Physical Therapists often see core weakness correlated with back and hip pain. So, what actually is “the core?”
Spoiler: it’s more than a 6 pack of abs! In addition to the ever-popular abdominals at the front of one’s body (rectus abdominis and transverse abdominis), the core also consists of obliques at the sides (internal and external obliques), muscles along the lumbar spine in the back (lumbar multfidi and quadratus lumborum), as well as the diaphragm at the top and the pelvic floor/hip flexors (iliopsoas) at the bottom. The “core” is essentially an anatomical box at the center of your body that helps transfer strength and force to your arms and legs for movement.
Knowing about the muscles that make up the core, gives insight into which exercises are best for it. For a long time, sit-ups and curl-ups have been the most common core exercises. However, those movements only target ab muscles at the front of that anatomical box. And while they might look pretty, without strength in all of the core muscles these “glamor” muscles will hit a limit in their ability to gain additional strength or definition. Imagine you only ever strengthened one finger in your hand- that won't help make your fist stronger.
So, how do we best exercise the core? Luckily researchers have used something called surface electromyography (sEMG) to measure the amount of muscle activation during various exercises. sEMG uses small pads applied to the skin to measure the intensity of muscular recruitment and contraction. With this information, it is possible to select exercises that optimize recruitment and strengthening of core muscles.
Floor exercises: Core Brace and Dead Bug
Ditch the traditional sit ups and opt into an exercise that targets the transversus abdominus, a muscle that wraps around the torso like a corset. To do this, lie on a mat with your arms extended straight over your chest so they form a perpendicular angle with your torso, then bend your hips and knees to a 90*-90* position. Tighten the muscles around your stomach and press your lower back into the mat/floor. For some, holding this position is challenging enough, but if that feels too easy, incorporate alternating leg lowers, just make sure your low back stays firmly pressed against the floor.
Physio ball Planks: The PB Plank Roll-Out and PB Leg Extensions Plank
These exercises are a variation on a traditional plank, except that instead of putting your arms or hands on the floor you use a ball. Adding a physio ball (or Swiss ball) to the exercise provides an element of instability which means more muscles are engaged overall. Begin in a kneeling position with the ball in front of you. Clasp hands together on the top of the ball. Go into a plank position keeping back long and abdominals tight. Add a “PB roll out” by pressing hands into the ball and roll it out in front of you until your forearms and your body is at a 45 degree angle. Use your forearms to pull back slowly and return to the starting position. OR you can try a “PB leg extension plank” by holding the plank pose over the ball and alternating lifting one leg off of the floor and then the other.
Free weight exercises: The Bulgarian Split Squat and The Back Squat
It may come as a surprise that exercises associated with hip and leg strengthening are equally beneficial for the core. In fact, these “leg” exercises are actually better at strengthening the core than a traditional sit-up is. To perform a back squat stand with feet shoulder-width apart with toes slightly pointed out, rest a loaded barbell across the back of your shoulders holding it with an overhand grip. Descend into a squat position by pushing your hips back and bending at the knee. At the bottom of the squat, pause, and then drive your hips upward bringing you back to starting position. For a bulgarian split squat, stand facing away from a bench or chair. Place one foot on the bench/chair that is behind you. Squat down with control until the right before the knee of the back leg touches the floor. Reverse the movement and extend your front leg again.
Strengthening the core is an important part of any exercise routine. Unfortunately, there are a lot of sub-optimal exercises floating around. The above is a list of some highly effective exercises that hit each of the major muscles constituting the core. However, these exercises are challenging and may not be appropriate for people suffering from injury or pain. Here’s where PT can help! If you’re worried about core weakness, or suffer from back or hip pain, a physical therapist can offer training and tailored exercises. By building a foundation of strength and body awareness, PTs can help you perform these exercises with good form and no pain.