You probably don’t spend a lot of time thinking about your obliques. Actually, scratch that – you probably don’t think about your obliques ever. But understanding what those long muscles that run along the sides of your waist actually do, especially as a part of your larger core, is crucial to understanding how you move as a runner. (Spoiler alert: They can help you move faster so you’ll want to keep reading.)

First, a quick physics refresher: “When we run, we create torque,” explains David Siik, the creative director of Precision Run at Equinox. “Everything is about this natural human movement of opposite arm, opposite leg. When you drive one knee forward, you create so much force in that one leg that if you didn’t have your opposite arm to counterbalance it, your body would literally rotate around.”

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That’s part of why your obliques are so important. These muscles stretch from your ribs down to your hip bones, and you use them when you twist your torso or lean over. During a run, they’re your core’s braking mechanism – your obliques keep your body from swiveling too far to one side of the other. “There’s a constant fight going in your body as it moves like a giant X,” explains Siik. “Your obliques are what help you move along your center line, keeping you from breaking that X.”

Your obliques play an especially critical role when you pick up the pace at the end of a long race or during speedwork, says Siik. When you start to fatigue, your neck starts to strain, your shoulders start to hunch, then your arm swing starts to get lazy, it comes down to your core (and those obliques!) to keep your body in check.

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The more you run, the more you’ll naturally develop stronger obliques. But you can help yourself along the way by incorporating exercises post-run that target not just your obliques (there’s no such thing as spot training, guys), but your whole core – which, after all, is responsible not just for helping you maintain your form on the run, but also literally keeping you upright at all times. It’s a win-win: You’ll be able to run stronger longer, and you might have a more chiseled middle to show for it.

How to use this list: The exercises below are demonstrated by Noam Tamir, certified strength and conditioning specialist, so you can learn proper form. Perform 3 sets of each as directed two to three times a week as a core workout or 2 sets twice a week immediately after a run as a post-run finisher. All you need is your own motivation, an exercise mat is optional.

1. Side Plank

Lie on your left side with your legs straight. Prop your upper body up on your left elbow and forearm with shoulder stacked directly over elbow. Brace your abs and lift hips to form a straight line from ankles to shoulders. Raise your right arm straight up toward the ceiling. Hold for 15 seconds, then rest for 5 seconds; repeat for 2 minutes.

2. Oblique Crossover

Lie face up with your hands placed lightly behind head, elbows out, knees bent, feet flat on the floor. Cross your left ankle over right knee. Breathe in, and on the exhale, peel your right shoulder off the mat and twist right elbow to left knee. Be sure not to pull on your neck with hands. Return to starting position. Repeat for 30 seconds then repeat on the other side, alternating for a total of 4 minutes.

3. Starfish

Lie face up on the floor with arms and legs extended, creating an X position. On the exhale, lift right arm and shoulder off the ground, while simultaneously lifting the left leg to tap right fingertips to left toes. Slowly lower back down to return to starting position, then repeat on the other side. Alternate arms and legs for 30 seconds, then rest for 10 seconds. Do 2 sets.

4. Isometric Quad Press

Lie face up with knees bent at 90 degrees and shins parallel to floor. Place your palms flat against your quads. Press your palms into your quads as hard as you can while simultaneously pushing back against your palms with your legs. Hold for 3 seconds, then rest for 3 seconds. Repeat for a total of 30 seconds, or no longer than 2 minutes.

5. Switch and Hold Bicycle Crunch

Lie face up with your lower back pressed into the ground, legs in table-top position with shins parallel to floor, and hands behind head, elbows out. Lift your shoulder blades off the mat, and straighten your right leg while rotating your upper body to the left, bringing right elbow toward left knee.

Hold for 3 seconds. Then, reverse to bring left elbow to right knee, and hold for 3 seconds. Continue to alternate sides for one minute, holding for 3 seconds in between each. Rest, then alternate sides for 1 minute, holding for 2 seconds on each side. Rest, then do alternate sides at a normal pace for 1 minute.

All images: Julia Hembree Smith
This article originally appeared on runnersworld.com.

READ MORE ON: core strength-training workouts