Squatting is a foundational human movement, along with pushing, pulling, rotation and hinging. And while you may hear warnings that squatting — especially with your thighs below parallel — is dangerous for your knees, that's a myth.
"Performing a deep squat, in which your thighs are below parallel is completely safe, and is actually healthy for your hip, knee and ankle joints," says Grayson Wickham, DPT, CSCS, founder of Movement Vault.
Plus, with proper biomechanics (and no preexisting knee injuries), you should be able to perform a deep squat without knee pain. However, it might not be possible if you have weak hips, reduced ankle mobility, lack of joint mobility or poor form.
Weak glute muscles, poor ankle mobility, improper form or an unrelated joint condition could be the reason you're experiencing knee pain from squats.
The Truth About Squats and Knee Pain
No matter what you've heard, full squats aren't bad for your knees. It's a resting position for people in Eastern countries, but Westerners typically lack the mobility to comfortably assume the position — which is likely partially responsible for the false belief that you can get a knee injury from squats below parallel.
The concern that causes many health professionals to warn against squatting below parallel is that it potentially increases the risk of knee laxity (weakness of the ligaments of the knee joint) and puts excessive pressure on the knee. However, according to a June 2014 study published in the Journal of Strength and Conditioning Research, that's untrue.
"The original thought that deep squatting would physiologically stretch out your knee joint capsule and that the ligaments surrounding your knee would become weak because of this is fundamentally flawed," Wickham says. As long as you have the mobility and stability in your hips and ankles and know how to perform a squat correctly, Wickham says there's no risk of knee damage.
In fact, squats can actually help with knee pain in certain circumstances. For example, an October 2019 study published in BioMed Research International found that squats reduced inflammation in the knee and supported its pain-free function for knee osteoarthritis patients.
Additionally, Wickham says one contributing factor to knee pain is having weak quadriceps, hamstrings and/or gluteus muscles. If that's you, squats can help tremendously, as long as they're performed in a pain-free range of motion using correct form, he says.
"As you increase the strength in these muscles around your knee joint, your knees will become more resilient to injury. During this process, as long as you are not aggravating your knee pain, your pain should progressively get better," says Wickham.
If you have undiagnosed knee pain, you should not continue to do full squats. Consult a physical therapist or work with a rehabilitation trainer to solve the problem that's causing your pain before resuming full squats.
1. Your Hips Are Weak
Physical therapist Jonathan Gayed says that in his experience, the most common reason for knee pain during squats is weak hip muscles — specifically the gluteal muscles.
The glutes help stabilize the knees. If the glutes are weak, the knees won't stay straight as you bend down, typically causing them to cave in from the force of the stronger quadriceps and inner thigh mucles. When this happens repetitively and under load (i.e., when you add weight), it can cause pain and tissue damage.
Fix it: Try one of these two moves to strengthen your glutes and hip muscles.
Move 1: Hip Thruster
- Sit on the floor in front of a weight bench, chair or couch, positioned lengthwise with your knees bent and your feet flat on the floor.
- Press your shoulders into the bench and raise your hips up to full extension. Keep your knees at a 90-degree angle.
- Lower down, then repeat.
If you want, you can place a barbell or a dumbbell across your hips (use a pad for cushioning).
Move 2: Outer Thigh Extensions
- Using the abductor machine at the gym or with a resistance band looped around your legs just about your knees, sit on an exercise bench (or chair).
- Open your knees against the resistance.
- Return to starting, actively resisting against the machine or band.
2. You Have Limited Ankle Mobility
You'll know if you don't have effective ankle mobility because you won't be able to get as deep in a squat as you'd like to. This can cause overcompensation that affects your form and increases the forces on your knees.
"When your ankles are not doing its job, your knee has to take over for your tight ankles," Wickham says. This compensation, he says, can lead to wear and tear in your knee joint and can eventually lead to pain and injury.
The most common ankle mobility issue, Wickham says, is having limited ankle dorsiflexion. "Ankle dorsiflexion is needed with almost every lower body movement you do including walking, running, lunges and squatting," he says.
Ankle dorsiflexion happens when your foot is on the ground and your knee tracks forward over the middle of your foot. You need to have good ankle dorsiflexion mobility in order to squat correctly and even more so when performing a deep squat correctly.
Fix it: Here are two moves that will help increase your ankle mobility and flexibility — ultimately helping you squat pain-free.
Move 1: Knee-to-Wall Ankle Mobilization
- Stand facing a wall with your toes about 4 inches from the wall. Place your palms on the wall and step one foot back as if you're going to do a calf stretch.
- Bend into your front knee as you shift the weight forward, attempting to touch the wall with your knee. Your back heel can lift but your front heel should stay on the floor.
- Do 10 reps, then switch sides.
Move 2: Banded Ankle Mobility
- Anchor a resistance band to something sturdy (like a table leg) and loop the other end around your ankle.
- Walk away from the anchor point until the band is taught.
- Kneel on the knee of the unbanded leg.
- Press forward, allowing the knee of the banded leg to extend beyond the banded ankle until you feel tension in your ankle.
- Hold three seconds, then release.
- Do 10 reps on each side.
3. You're Using Improper Form
You can really mess up your body if you use incorrect squat form, especially if you're doing them with a considerable amount of weight. The wrong form can put too much pressure on your knees, which can cause an acute knee injury or can lead to an overuse injury over time.
Wickham says correct form includes keeping your heels on the ground the entire time, as well as not allowing your knees to buckle inward. You also want to make sure your knees are pushing outward (but not too far outward) when you descend into your squat, he says. Your knees should track over the middle of your feet.
"Letting your heels raise and/or your knees buckle inward are the two biggest mistakes that will lead to knee pain while squatting," he says.
Fix it: The key is to go back to basics. Get rid of the weight and practice proper technique, the finer points of which are:
- Stand tall in an athletic stance — feet hip-width apart and your toes pointed slightly out.
- Keep your weight in your midfoot.
- Bend your knees and shift your hips back slightly as you lower down without overarching in your lower back.
- Lower as far down as you can without letting your knees pass beyond your toes or your knees bow inward.
- At the bottom, check to make sure you're maintaining a neutral spine and an upward posture with the chest out, shoulders back and the gaze forward.
- Straighten your knees and press your hips forward as you return to standing, squeezing your glutes at the top.
It's a great idea to consult a certified personal trainer or physical therapist who can observe your form and provide feedback about anything that is contributing to your knee pain. Only when you're able to complete 20 body-weight squats with correct form should you begin to add weight.
Another effective way to practice proper squatting form and prevent sore knees after squats is to perform box squats. This trains proper squatting technique by reinforcing the hip hinge and the motion of pushing the hips back. They're simple to do:
- Pace a plyo box or weight bench behind you as you're squatting.
- Reach your hips back and sit down on the bench.
- Stand up again.
- Maintain all other points of your proper squatting form as outlined above.
4. You Have an Unrelated Knee Condition
It's possible that your knee pain isn't related to squatting but is exacerbated by the movement, causing sharp knee pain when squatting. Wickham says you'll want to stay away from deep squatting if you have any knee pain while performing the squat, directly afterward, or within a 24 hour period after performing the squats.
Common conditions that can cause pain in one or both knees include:
- Patellar tendinitis: an overuse injury that causes irritation and inflammation of the tendons of the knee
- Osteoarthritis: a degenerative arthritis that occurs when cartilage in the knee decreases with wear-and-tear and age
- Knee bursitis: inflammation in the small sacs of fluid — called bursae — that cushion your knee joint
Fix it: If you've tried strengthening your hips, improving your ankle mobility and working on your form and you still have knee pain, make an appointment with your doctor.
Additional reporting from Sara Lindberg
- Journal of Strength and Conditioning Research: Knee Joint Kinetics in Relation to Commonly Prescribed Squat Loads and Depths
- Mayo Clinic: Knee Pain
- BioMed Research International: Static Low-Angle Squatting Reduces the Intra-Articular Inflammatory Cytokines and Improves the Performance of Patients with Knee Osteoarthritis
- Jonathan Gayed: Top 3 Reasons Why Your Knee Hurts When You Squat and Their Fixes
- Cedar's Sinai: Patellar tendinitis
- Arthritis Foundation: Osteoarthritis
- American Academy of Orthopaedic Surgeons: Knee bursitis