Whether it’s for function or aesthetics, lots of people want a strong core. There’s just one problem: “Most people assume that the rectus abdominis, commonly identified as the ‘six-pack muscle,’ is the only core muscle in the body,” explains Sara Mikulsky, DPT.
Some people also know about the external obliques, which are located on either side of the rectus abdominis. “But this is only one muscle group amongst many that contribute to generating our core strength and stability,” says Elisa Withers, a physiotherapist, Pilates master trainer and co-founder of Australian Physiotherapy and Pilates Institute (APPI).
If you’re wondering why this matters, there are a few reasons. Most people prioritize exercises that work the rectus abdominis, such as crunches, in their core workouts. But as the abdominal muscle furthest away from the spine, it actually plays the smallest role in core strength, Withers says. “People often don’t realize the rectus looks great, but is not actually attached to the spine at all,” Withers notes. “Therefore it doesn’t protect the back from injury and is only a tiny part of a strong core.”
What’s more, focusing only on the outer, more visible core muscles can set you up for muscle imbalances. “Imagine your body like a building,” Withers says. “The most crucial structure in the building is the foundation. The outer poles and beams can be really strong, but if the foundation is weak, the building is unstable.” An unstable foundation could lead to injuries and pain down the road.
The takeaway: You want to focus on both the inner and outer muscles of your core, ensuring they’re balanced and all working properly — regardless of whether your goals are functional, aesthetic or somewhere in between.
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CORE ANATOMY 101: THE MUSCLES YOU NEED TO KNOW
First, it’s important to know there are many ways to categorize core muscles. For the purposes of this article, we’ll break them down into “global” and “local.”
“The global core muscles include the larger superficial (surface) muscles that have minimal or no direct attachments to the spine,” explains Leada Malek, DPT, a board-certified sports specialist. These include the rectus abdominis, external obliques and parts of the erector spinae and quadratus lumborum. These muscles are visible on the outside (provided body fat is low enough). They provide some stability, but can’t help stabilize individual segments of the spine.
On the other hand, the local core muscles are smaller and located deeper in your body, Malek says. These muscles include the transverse abdominis, internal obliques and multifidus. They attach to the spine and thoracolumbar fascia, which forms a ‘corset’ around the spine. These are your stabilizing muscles.
Here’s a quick breakdown of what each key core muscle does and why it’s important.
Rectus abdominis: This is the classic six-pack muscle. It helps you bend forward, like when you do a situp, explains Nick Occhipinti, certified strength and conditioning coach. It also helps you lift your legs when your upper body is fixed, for instance, when you do a hanging leg raise.
Internal and external obliques: “The obliques are large muscles on our flanks that extend from both sides of our body all along the ribs and attach to the sides of the rectus abdominis,” Occhipinti says. “These muscles are responsible for some core rotation both to and away, as their fibers (external versus internal) go in opposite directions. Often, these muscles are trained with cable or medicine ball chops, rotations and bicycle crunches.”
Transverse abdominis: This is the unsung hero of your core musculature. “I always show people how to activate their transverse abdominis, the “corset” muscle, because of how much it contributes to added stability because of how it attaches to the sides of the spine,” Malek says. People with back pain often have a poorly-functioning transverse abdominis. What’s more, learning how to engage it is often the missing link in people who engage in lots of core training but aren’t seeing any results. As for how to find it, it’s the muscle in the lower abs that kicks in when you cough or laugh, according to Malek.
Spinal erectors (erector spinae), quadratus lumborum and multifidus: These muscles are opposite the rectus abdominis on the back side of the body. They can be trained with some standard core exercises like planks and side planks, Occhipinti says, but can be directly targeted with back extension exercises like supermans and Roman chair back extensions as well as deadlifts.
The multifidus are deep back stabilizers. “They help maintain alignment of the spine, especially when bending backward,” Mikulsky says. “These muscles are quite small, so they are often missed in an exercise program.”
Pelvic floor: This is a group of muscles found at the bottom of the core. It might not seem like the most important area to pay attention to, but without a stable base, it’s difficult to work on strengthening the other muscles, Mikulsky explains.
Diaphragm: “Most people don’t think of the diaphragm as a muscle that can be trained or a core muscle at all, but it is in fact both,” Occhipinti says. In the same way the pelvic floor forms the bottom of the core, the diaphragm forms the top. The diaphragm is mostly used to breathe, which creates core tension that allows us to stabilize and strengthen all the muscles of the core.
5 CORE EXERCISES TO TRY
If you’re ready to move beyond crunches, here are some expert-approved exercises that will help you engage and strengthen your whole core instead of just your rectus abdominis.
1. DIAPHRAGMATIC BREATHING
The goal of this breathing exercise is to learn how to use your whole diaphragm to breathe, getting 360 degrees of expansion every time you inhale.
Lie on your back with your feet flat on the floor and knees bent. “Begin with deep diaphragmatic breaths ensuring that the chest is not rising and falling, and only the upper abdomen is moving,” Occhipinti instructs. Then, shift your focus to getting your rib cage to expand sideways with each breath. Next, move to an all-fours position and focus on adding expansion in the back of your ribcage as you inhale. “This is a difficult task, but very worthwhile,” Occhipinti says.
2. TRANSVERSE ABDOMINIS BRACING
You can locate your transverse abdominis by feeling the bony points of your hips and moving your fingers an inch toward your belly button. “Take a normal breath in, then exhale as if you are blowing a stream of candles out as you draw in your lower abdomen,” Malek says. You should feel the muscles tighten \underneath your fingers. “Try not to hold your breath or do a crunch to achieve this,” Malek says. Once you master this, try this breathing pattern and bracing to intensify core engagement in virtually any exercise.
3. MULTIFIDUS ACTIVATION
“Once you’ve mastered controlled activation of the transverse abdominis, you can try to improve the mind-muscle connection with the multifidi,” Malek says. “This one is trickier.”
Lying on your stomach, draw in your core like you did in the transverse abdominis activation. Then, squeeze your glutes. Next, attempt to lift your ribs and legs up like a “superman” exercise — but here’s the kicker — don’t arch your low back. “If you do end up extending the back, it’s likely you’ve now recruited too much of the bigger erector spinae muscles,” Malek says.
4. FARMER’S CARRY
The most basic form of this exercise is to walk with your best posture while carrying two heavy dumbbells, one in each hand. “This exercise trains the erectors, transverse abdominis, and the obliques, as well as other muscles to maintain an upright and strong posture while carrying a heavy load,” Occhipinti says. You can recruit even more core muscles if you try a suitcase carry (which involves carrying a weight only on one side) or an offset carry (one dumbbell overhead and another at your side).
5. ANTI-ROTATION VARIATIONS
These exercises recruit many core muscles at once to work on stability, Occhipinti explains. One of the classic anti-rotation exercises is the Pallof press.
Grab a long resistance band and loop it around a fixed pole, and turning to one side, hold the handles or end of the band in front of your chest. Walk away from the wall until you feel tension on the band. From there, push your hands out in front of you in a straight line. You should feel your core working to maintain your position. Do 8 reps, then face the opposite direction and repeat.
Other anti-rotation exercises to try include stir-the-pot, plank taps and renegade rows.
Check out “Workout Routines” in the MyFitnessPal app to discover and log a variety of workouts, or build your own routine with exercises that fit your goals.