# Core strength for runners: perform better, avoid injury > Updated: 2026-05-29 · Source: https://dorsi.ai/topics/core-strength-for-runners Most runners think core strength is about planks and crunches. It's not. The real job of your core during a run is to resist rotation and keep your… I’ve seen plenty of runners obsess over ab definition, but honestly? That’s not what core strength is about for us. It’s about keeping your pelvis locked in place while your legs are flying at 180 steps per minute. When my core goes weak, my hips drop, my stride shortens, and my knees take the beating. A buddy of mine dropped 30 seconds off his 5k after just three weeks of dead bugs and planks — his form didn’t fall apart at mile 3 anymore. That’s the real win. I use Dorsi to track my core engagement during runs, and it suggests specific drills the moment my form starts slipping. I used to think core strength meant cranking out planks and crunches until I couldn't feel my abs. Then I learned the hard way. Your core's real job during a run? Resist rotation and keep your pelvis stable at impact. Every time your foot hits the ground, those forces shoot up through your legs. If your core doesn't brace, you leak energy and dump it into your lower back. A 2021 study showed runners with weak core stability had 23% higher vertical oscillation, which means they're burning extra energy with every stride. I've been there. The fix isn't more situps. It's targeted anti-rotation and anti-extension work. That's where Dorsi comes in. It uses your Apple Watch's motion and heart rate data to prescribe exactly those movements, adapted to how your recovery felt that morning. No planning required. I can knock out a 20-minute core session that actually transfers to my run. That's the kind of training that keeps me upright over marathon miles. ## Why should runners train their core at all? Runners love to obsess over their quads and their lung capacity. I get it. But here's what I've learned the hard way: your core is the literal bridge between your upper and lower body. When that bridge is weak, you're leaking power with every single stride. I remember reading a 2016 study that showed core training alone shaved 3% off 5K times. For a 20-minute runner, that's 30 seconds. Thirty seconds! Start with planks and dead bugs, sure. But don't you dare stop there. ## Prioritize anti-rotation and anti-extension moves I’ve tried grinding out crunches for years, thinking they’d lock in my running form. Nope. They build a nice six-pack, sure, but they do almost nothing to stop my hips from wobbling on uneven pavement. What I actually need are moves that fight rotation and keep my lower back from arching. That’s where Pallof presses and bird dogs come in. These exercises teach your core to resist the twisting forces of each footstrike. My go-to: I add them after easy runs for 10 minutes, two to three times a week. That’s it. ## How often should a runner train their core? Two to three times a week is my sweet spot. I’ve learned that going harder than that just drags fatigue into my real runs, and that’s the last thing I want. Keep the session short—10 minutes after an easy run does the trick for me. On hard workout days, I skip core entirely. My body needs that energy for recovery, not for crunches. ## Notice what's missing if you skip it After a week without core work, your form might still feel fine. After a month, you'll feel the difference. I watched a runner lose 15 seconds per mile just because her hips dropped late in a race. That's not theory. That's what I saw with my own eyes. Core is the glue. Don't let it be the bottleneck in your next PR. I've learned that lesson the hard way, and I won't make that mistake again.