I used to laugh off the small stuff.
I was the runner who’d log 50-mile weeks and the lifter who chased heavy squats—but ask me to lie on the floor and do clamshells? Forget it.
That changed the day my hip sent me a not-so-subtle message.
Sharp twinge, followed by weeks of nagging IT band pain.
Suddenly, sitting hurt.
Running? Off the table.
I was limping through life and mad about it.
That’s when my PT handed me the most humbling assignment of my running life: Lie down and open your knees like a clamshell.
I rolled my eyes so hard I nearly strained something else. But I was desperate. So I did it. And I kept doing it.
Fast-forward a few weeks? My hips were stronger.
My knee stopped aching.
And just like that, I was running pain-free again.
So yeah—I’m now that guy who preaches clamshells to every runner I coach.
Because they work. They’re not flashy, they’re not sexy, and your gym buddies won’t be impressed.
But they’ll keep you out there logging miles instead of icing sore hips on your couch.
What’s a Clamshell Exercise, Anyway?
Simple setup: lie on your side, knees bent, feet stacked. Keep your feet together, and lift the top knee like you’re opening a clamshell.
That’s it.
But don’t let the simplicity fool you—this move hits muscles most runners ignore.
Namely:
- Gluteus medius – The stabilizer on the outside of your butt
- Hip rotators – Deep little guys that keep your legs aligned
- Core – Yep, it fires that too (if you do it right)
Clamshells were born in rehab settings and Pilates classes.
They’re low-impact, slow, and designed to activate, not annihilate.
Think of them as a wake-up call to sleepy stabilizers.
A lot of runners go hard on squats and lunges—great. But those big moves often let the smaller hip muscles off the hook.
Clamshells bring them back into the game.
Why Every Runner Should Be Doing Clamshells
Let’s break down exactly why this little move belongs in your toolkit.
1. They Wake Up Your Glute Medius (AKA the Pelvic Boss)
This muscle’s job? Keep your pelvis stable every time your foot hits the ground.
Weak glute medius? You get the dreaded hip drop, poor alignment, and overcompensation everywhere else—knees, IT band, even lower back.
Strong glute medius? You stay aligned, strong, and smooth.
Clamshells hone in on that muscle like a laser.
You’re not just building strength—you’re teaching your brain to fire the right muscle at the right time. That neuromuscular connection is key.
Ever heard of “dead butt syndrome”? Clamshells are one of the antidotes.
2. They Fight Off Knee, Hip & IT Band Pain
I’ve seen this first-hand over and over: runners with chronic IT band pain, patellar tracking issues, or mystery hip tightness?
Nine times out of ten, weak glutes are part of the problem – or even, in some cases, the root-cause of the issue.
Clamshells fix that imbalance by strengthening the muscles that keep your leg aligned as you run.
One of my athletes had knee pain that flared up every long run.
We added clamshells daily, and boom—within a few weeks, pain dropped off. No magic, just better muscle control and balance.
Science backs it too:
- A review in JOSPT showed clamshells as one of the most effective hip-strengthening exercises.
- Rehab protocols for runner’s knee almost always include clamshells for a reason—they help rebalance the load so your knee isn’t doing all the work.
Your hips are the steering wheel. Strengthen them, and your whole body drives smoother.
3. They Build a Foundation (Runners, Lifters, Desk Jockeys – Listen Up)
You don’t need to be training for a marathon to benefit from clamshells.
- Lifters use them to improve squat mechanics.
- PTs use them to fix back pain.
- Office workers? You probably have sleepy glutes too—clamshells can help reset the system.
Even elite athletes throw these in their warm-up routines because they know: when the small muscles fire first, the big ones follow better.
If you’ve ever felt your hamstrings or quads take over during squats, try doing 2–3 sets of clamshells beforehand. You’ll feel your glutes light up—and your form tighten up.
No Gym? No Excuse
Clamshells are as no-BS as it gets. No machines, no fancy gear. Just you, the floor, and gravity.
They’re the ideal bodyweight exercise for runners.
Watching Netflix? Do a set.
Stuck in a hotel room on a work trip? Do a set.
Cooling down after a run? You get the idea.
You don’t even need resistance bands to get benefits (though they do ramp things up).
The barrier to entry is zero, which is why physios and coaches hand them out like candy — because you’ll actually do them.
They’re joint-friendly, low-impact, and take up about as much space as your foam roller. Add a few sets to your rest days or warm-ups and they’ll quietly start building serious hip strength.
This, overtime, guards you against all sorts of overuse injury. What’s not to like, really!
Builds Symmetry & Hip Stability (No More Wobble)
Here’s the deal: your body is a master at compensating.
If your glutes are asleep, other muscles step in — but that often leads to breakdown.
Clamshells target the gluteus medius, that sneaky little muscle on the side of your hip that stabilizes everything when you run, squat, or walk stairs.
Strengthening it balances the load between your outer hips, thighs, and core.
That means fewer wobbly landings, less knee collapse, and a smoother stride.
Ever feel your knee cave inward on squats? Or your hip drop on one side when running? That’s your glute med not doing its job. Clamshells fix that.
Makes Your Big Lifts Better (Yes, Really)
Want to squat deeper? Lunge with more control? Stop your back from taking over deadlifts? Clamshells help you get there.
They fire up the hip abductors and external rotators — the muscles that keep your knees tracking over your toes and prevent your pelvis from tipping.
And when your glutes are properly activated, your quads and hamstrings don’t have to carry the whole show.
Do a few sets of clamshells before squats, and you might be surprised at how much cleaner your form feels.
It’s pre-activation that primes your glutes so they show up when it counts.
How to Do the Classic Clamshell (The Right Way)
The clamshell is a simple move—but don’t let that fool you. Most runners either rush it or butcher the form, and then wonder why their glutes aren’t firing.
Do it right, and your glute medius (aka the muscle that keeps your hips stable and knees happy) will light up in a good way.
Let’s break it down so you get the full benefit.
Step-by-Step: Classic Clamshell Form
- Lie on your right side on a mat or soft surface.
- Stack your left leg directly on top of your right, knees bent at about 90°.
- Your knees should be slightly in front of you, feet in line with your butt.
- Feet stay stacked, and your hips stay stacked—left hip right over right, no tipping back.
- Rest your head on your right arm or a pillow so you’re not straining your neck.
Brace That Core
Pull your belly button in just slightly—like someone’s about to lightly jab your stomach. This keeps your pelvis stable and your spine from twisting.
Lift the Top Knee (Slow and Controlled)
Keep your feet touching, and raise your top knee (left) as high as you can without rolling your hips. This is the clamshell “opening.”
Your movement is at the hip, not the back or waist.
🧠 Form cue: Imagine a hinge at your hip joint. Your knee opens, but your pelvis stays frozen. If your top hip rolls back, you’re cheating and missing the glutes.
Don’t Overdo the Range
Most people max out around 45°–60°. You don’t need to go crazy high. Just get enough lift to feel that upper butt working.
Pause and Squeeze at the Top
Hold for a second at the top. Squeeze your glutes. This pause is where the magic happens.
Lower with Control
Bring the knee back down slowly. No flopping. Take 2–3 seconds.
Eccentric control = stronger hips.
Reps and Burn
Go for 12–20 reps per side, depending on your current strength. Start lower if you’re new. Do 2–3 sets.
If 20 feels like a breeze? Time to add a resistance band or level up.
Switch Sides
Roll over and hit the other side for the same number of reps. Balance matters.
Pro Tips to Nail Your Clamshells
- Keep hips stacked like you’re resting against a wall—don’t roll open.
- Thighs stay angled about 45° in front of your torso—don’t let the knees drift up toward your chest.
- Spine neutral—no twisting, no arching.
- Feet together at all times.
- Abs engaged the whole way to stop pelvic tilting and protect your back.
- Feel the burn in your glute, not your lower back or IT band.
If you’re feeling it in the wrong spots, slow down and reset your form.
Who Should Be Doing Clamshells? (Short Answer: Pretty Much Everyone)
Runners & Endurance Athletes
If you run — even casually — you need clamshells. Period.
Every stride puts you in a single-leg stance. That’s a stability challenge. Weak glutes = poor form = injuries.
We’re talking IT band syndrome, runner’s knee, hip pain, shin splints, ankle sprains — the whole messy list.
Your foot or knee pain? Probably starts with weak hips.
Clamshells target your glute medius — the little side butt muscle that keeps your stride aligned and your pelvis level.
In fact, studies show that hip strengthening beats knee-only exercises when it comes to fixing runner’s knee.
Add clamshells to your weekly routine — especially during peak mileage or race prep. They’re injury insurance.
Lifters, CrossFitters, and Booty Builders
Lifters, listen up: if your knees cave in on squats, or you struggle to feel your glutes in deadlifts, guess what?
You’re likely under-activating your glute medius.
Clamshells help fix that. They strengthen the hip abductors and retrain the glutes to fire properly.
This means better mechanics, more power, and less risk of injury.
Even bodybuilders use clamshells or cable abductions to round out the upper glute — yep, that’s glute medius, giving your butt that nice wide cap.
No shame in chasing aesthetics and performance.
Desk Warriors & Sedentary Folks
Sitting all day turns your glutes off. It’s called glute amnesia — and it’s real.
Meanwhile, your hip flexors get tight and start yanking on everything. That’s how you get low back pain, poor posture, and hip dysfunction.
Clamshells are the antidote. You can literally do them while watching Netflix.
Even 2–3 sets every other day will start reversing the damage. Wake up your butt and take the pressure off your spine.
Your posture (and future back) will thank you.
Rehab Warriors
Got knee surgery, hip surgery, or low back pain? Clamshells are one of the first things a good PT will throw into your plan.
Why? Because they safely re-strengthen the hips without loading the injured joint. Gentle, controlled, low-impact — and ridiculously effective when done right.
I’ve seen clamshells used for:
- ACL rehab
- Post-hip surgery strength
- Chronic low back pain relief
- Early-stage return-to-walk training
Studies show that people with back pain often have weaker hips. Strengthen the hips, and everything else feels better.
If you’re rehabbing, follow your therapist’s plan. But know this — clamshells are probably coming your way.
Older Adults or Anyone Working on Balance
As we age, we lose hip strength and balance. That’s what causes so many falls — not clumsiness, just weakness.
Clamshells are perfect because:
- They’re done lying down
- They’re safe and stable
- They directly improve hip control for walking and balance
Mix them with bridges or gentle leg lifts, and you’ve got a solid base program for staying strong and upright for years to come.
Common Clamshell Mistakes (and How to Fix Them)
Clamshells look simple—and they are. But don’t let that fool you.
Bad form can turn this great glute move into a total waste of time (or worse, an injury waiting to happen).
Here’s what I tell runners who aren’t feeling the burn where they should, or are wondering why their hips still suck even after doing “all the right stuff.”
1. Rolling Your Hips Back
This one’s the biggie. As soon as your top hip starts to roll backward, you’re out of position. What you think is glute work turns into TFL or lower back compensation.
Fix it:
- Keep your hips stacked vertically—think: one hip right over the other
- Only the top knee moves, not your whole body
- Do it with your back against a wall—if your hips or shoulders come off the wall, you’re cheating
👊 Coach tip: Smaller range, strict form > big range, sloppy reps.
2. Speeding Through Reps
Going fast might feel like a workout, but momentum isn’t muscle. If you’re bouncing your knee up and down, you’re not actually working the glute.
Fix it:
- Go slow and controlled
- Pause at the top for a beat—squeeze your glute
- Lower down just as slow
You should feel the burn kick in around rep 10. If you don’t, slow it down more.
3. Not Squeezing at the Top
That “open like a clam” position? That’s where the magic happens. If you just tap that spot and drop back down, you miss the whole point.
Fix it:
- Pause at the top, even just for a second
- Actively squeeze your glute
- Don’t just go through the motion—engage the muscle
🎯 Think: lift, squeeze, then lower. That’s a full rep.
4. Knees and Feet Drifting
As you rep out, your setup might start shifting—knees inching forward, feet sliding around. That changes the angle and pulls in the wrong muscles.
Fix it:
- Start with knees bent about 90°
- Feet in line with your body
- Keep everything locked in—only the top knee opens
If your bottom leg is sliding? Reset. If your knees creep up toward your chest? Reset.
5. Tension in the Neck and Shoulders
Weird, but common. You’re working your hips, but suddenly your neck’s stiff and your traps are on fire.
Fix it:
- Relax your upper body
- Support your head with your hand or a pillow
- Let your face and shoulders chill—all the work should be below the belt
6. Feeling It in the Wrong Places
If your lower back, IT band, or hip flexors are taking the heat? Something’s off.
Fix it:
- Check your hip position—are you rolling back?
- Slow it down, engage the glute consciously
- Try pressing your heels together—it helps cue the glute
- You can even poke your glute while doing the rep—yes, seriously. It boosts muscle activation
One runner said, “I feel it everywhere but my glutes!” That’s a dead giveaway that your form needs a reset.
7. Doing Too Much Too Soon
Clamshells seem easy—until you do them right. If you go from zero to 3 sets of 30 with a heavy band, you might end up sore in all the wrong places.
Fix it:
- Start small: 1 set of 10–15 unbanded reps
- See how you feel the next day
- Add a band or more reps only when your body says it’s ready
Don’t let ego wreck your hips. Progress takes consistency, not heroics.
Final Thoughts: Boring, Unsexy… and Absolutely Essential
Let’s be honest—clamshells aren’t sexy. No one’s flexing after a killer set of clamshells. You’re not gonna post a time-lapse of you knocking out reps next to your foam roller and get a thousand likes.
But here’s the truth I’ve learned after years of running and coaching: it’s the boring stuff that saves your butt—literally.
Clamshells won’t give you a pump. They won’t leave you gasping for air. But they will do something way more important: keep you in the game.
When you’re 18 miles into a marathon, or deep into a squat cycle and your form holds, that’s clamshells doing their quiet work.
Foundations First
In my playbook glutes and hips are your foundation.
That’s your power center.
And if it’s weak, it’s just a matter of time before your knee hurts, your IT band flames up, or your piriformis locks up like a vice.
I tell my athletes this all the time:
“If you skip the small stuff, don’t be surprised when the big injuries show up.”
Clamshells are the small stuff. They’re the no-glory, rehab-style drills that actually fix the real issues.
They teach your body to fire the right muscles, the right way, at the right time. That’s how you move better, stay pain-free, and rack up miles without breaking down.
Your Turn
- Have clamshells saved your running career like they did mine?
- Got a favorite way to sneak them into your routine?
- Or still doubting the power of the “boring stuff”?
Drop a comment. Let’s hear it.
Because consistency beats cool. And the clamshell?
It’s the unsung hero of strong, injury-free running.