As runners, most of our focus tends to go to our legs: how much push-off can you generate from your calves, how powerful are your quads, how much range of motion do you have in your hips?
But here’s a fun fact: More than 70 percent of a runner’s total energy expenditure is used to support their body weight; only around 20 percent is used for forward propulsion. And you know what muscle group does the lion’s share of keeping you upright? Your core.
Why Is Your Core So Important In Running?
People hear “core” and think “abs.” But your abs—aka the rectus abdominis, a long muscle that runs from the pubic bone to the sternum—make up only a fraction of your actual core, says Natalie Niemczyk, C.S.C.S., an RRCA-certified running coach, running technique specialist, and owner of Revolution Running Company and Revolution Running Physical Therapy.
The core also includes the transversus abdominis, a deep layer of muscle that stabilizes the spine; the multifidus, a group of small muscles alongside the spine that also help with stabilization; the internal and external obliques, which help flex and rotate the trunk; the erector spinae, three long muscles along the spine which help straighten and rotate the back; the diaphragm, which raises and lowers the ribs as you fill and empty your lungs; and the pelvic floor muscles, which support and stabilize the pelvis and spine. Even your glutes, lats, and traps are considered minor core muscles.
“Your core is the foundation or base of performance,” explains Niemczyk. “If that isn’t solid, it will affect your efficiency, power, and injury risk while you’re running.”
That’s because all motion stems from your core during running. As you move through your gait, you’re hitting all four basic movement patterns: pushing, pulling, squatting, and hinging, says Angelina Ramos, cross-country coach at the University of Nevada, Las Vegas. “Your core’s job is to keep you nice and tall, protecting your spine, stabilizing your landing and push-off, and allowing for full range of motion in your hips,” she explains.
If your core is weak, the longer you run, the harder it will be to maintain proper form. Picture runners at the end of a marathon, when their shoulders drop, hips pop, knees cave inward, and so on. Any of those scenarios is going to make you less efficient, says Ramos, forcing you to use more energy (by compensating with less powerful muscles) than you would if your core was stabilized and engaged.
The best way to enhance your performance is to maximize your force production while minimizing the expenditure that has on your joints, says Niemczyk. “And the biggest driving factor in that is trunk and pelvic control. If you don’t have that strong foundation, you won’t get the power you need out of your hips and quads and hamstrings.”
Why What Your Stomach Looks Like Doesn’t Matter
Whether you’re watching elite races or just scrolling through running Instagram, it’s easy to get caught up in the flat, defined abs on what seems like every female runner.
But those six-pack abs are the most superficial layer of the core, says Niemczyk. “Plenty of people have six-pack abs and don’t have proper trunk or pelvic control,” she adds. “You actually need to get into the deep core musculature to optimize how well you run.”
Plus, that six-pack look isn’t just about chiseled muscles. The rectus abdominis has fibrous bands called tendinous intersections on top of it which help support forward flexion; it’s that connective tissue that causes the grooves you actually see on someone’s abs. Thanks to genetics, it’s possible that your connective tissue doesn’t extend all the way across your rectus abdominis—and so it wouldn’t create that six-pack look.
And, not for nothing, “you have to feed a six-pack,” says Ramos. “To see that kind of muscle definition, you have to be eating enough protein.” There’s a genetic factor here, as well; that look will depend on where your body tends to carry fat and your hormone profile. “A lot of people think they just need to eat less and get skinnier, but that’s not the answer.”
When your focus is performance, it doesn’t matter what your abs look like, even if you’re trying to emulate the most elite runners. “You’re an individual case study of one,” says Ramos. “What works for Shalane Flanagan is not necessarily going to work for you. You need to prioritize how you feel and doing the work that makes you feel powerful more so than paying attention to what you look like.”
How to Engage Your Core to Run Stronger
There’s a big difference between having strong abs and being able to activate your core while running—unfortunately, it’s really easy to run without engaging your core, but it’s going to make it a lot harder for you.
One of the best ways to turn on your core is through anti-rotational, anti-flexion training, says Ramos. That sounds complicated, but it’s all about stabilization. Think: resistance band presses, front rack carries, side planks, single-leg lateral hops on to a step or box, lateral medicine ball throws, overhead squats, or even short bursts of running with a medicine ball held overhead or straight out in front of you.
What these exercises do is engage and train your core to resist movement. You’ve got to stabilize from your calves all the way up to your shoulders so your body isn’t flailing around, wasting energy, and “that is very sport-specific to when you’ve got the majority of your weight on your front foot in a split stance during a running stride,” Ramos explains. “And that ability to resist movement and resist collapsing under fatigue is what’s going to help you stay tall at the end of the race so you can put your energy towards what matters: crossing the finish line.”
What you shouldn’t do is prescribe yourself hundreds of crunches. But rounding at the spine over and over again like that actually isn’t great for you, and you’re going to get way more out of holding a strong plank for an extended period of time. Even better, head to the weight room. “You’re going to engage your core 10 times harder in a squat and a lot of your basic power lifts than you ever will doing crunches,” says Ramos.
Breath is another really important way to keep your core engaged, says Niemczyk. “A lot of times, when people are exerting themselves, they’ll hold their breath.” You actually can’t engage your core while holding your breath; the transversus abdominis engages naturally every time you exhale. Obviously, most runners aren’t holding their breath, but make sure you’re not taking shallow breaths into your chest, she says, and focus on deep belly breaths that expand your diaphragm and rib cage horizontally on the inhale. That opens up more space for oxygen in your lungs, which means more oxygen will get to your working muscles.
Practicing this kind of training and breathwork when you’re off the road, treadmill, or trail will prime your core to activate when you do run. Because activating your core isn’t something you should be preoccupying yourself with while you’re running. It should be second nature by the time you lace up.