One of the most frequent complaints I hear from clients is, “I can’t squat, because it hurts my knees.” Sometimes there’s a variation like, “My doctor says I shouldn’t squat because it hurts my knees.” So is this common notion right or wrong? Let’s dive in and see what both experience and science tells us.
I recently read a Dan John blog post in which the legendary coach responded to an athlete’s assertion that “squatting hurts my knees”1 by asking the young man to do a squat. After seeing how he performed this staple lower body exercise, Dan said, “Squats don’t hurt your knees; whatever you are doing there hurts your knees.” This speaks to the fact that a lot of people have grooved incorrect and even potentially damaging squat patterns. This could be because they’ve never had any coaching, or that someone showed them the wrong technique years ago and it stuck.
Making Movement Compensations
For others, their injury history is a window into a faulty squatting pattern. When we get hurt, our bodies will do anything to avoid repeating it, and so we often create compensations or workarounds that we might not even notice. Sometimes these are what makes squatting painful. Another common error is to not only use a dysfunctional pattern but to load it with a ton of weight. It’s all very well to throw several plates on either side of a barbell and go to town, but only if you can first show me that you can perform a sustainable unweighted squat and then maintain the integrity of the movement with a lighter weight before you try to bend the bar.
Another common barrier to squatting well is that many people don’t do it often or at all. Squats are a staple in performance-focused weight rooms in schools, colleges, and sports team facilities, but in commercial gyms they’re not considered sexy enough. It’s shots of six-pack abs, bulging biceps, and curvy butts that people believe will get them more social media followers, and they think squats won’t check any of these boxes (despite the fact that squatting does actually strengthen your core and glutes). That’s why crunches, curls, and whatever new-fangled exercise that’s trending today are the go-to exercises for the gym mirror selfie crowd.
What Do Studies Say About Squatting?
When trying to tackle the notion that squats hurt people’s knees, I often share real-world experiences I’ve gleaned from working with everyone from NBA players at the LA Lakers to weekend warriors and everyone in between. But some people won’t be convinprced unless they’re presented with third-party evidence. Which is where scientific studies come into play.
A paper published in Medicine & Science in Sports & Exercise compared squatting to other lower body exercises. The author wrote that, “Overall, the squat generated approximately twice as much hamstring activity as the leg press and knee extensions.”2 Squatting also exposed the PCL and ACL to double the load, which other studies have shown is necessary for increasing ligament durability. In a subsequent study, one of the same co-authors concluded that, “The squat does not compromise knee stability, and can enhance stability if performed correctly. Finally, the squat can be effective in developing hip, knee, and ankle musculature, because moderate to high quadriceps, hamstrings, and gastrocnemius activity were produced during the squat.”3 He also noted that squatting helps improve rehab from knee injuries.
We often hear talk of “functional” movements being those that transfer best from the gym to real life activities. If this is our definition, then squats are highly functional for all age groups. As I alluded to in a recent article, squatting is a fundamental skill (along with jumping and sprinting) that we should work hard to maintain as we get older. To this end, a group of researchers had older adults perform a squat protocol for 12 weeks4. At the end of the program, their leg strength – as shown by a one-rep max leg press – improved significantly. They also did better on a sit-to-stand test that’s often used in clinical settings to assess mobility and stability in the elderly.
What about those who have an existing joint issue? A team of Chinese exercise scientists asked people with advanced osteoarthritis to perform static squats twice a day5. After a year, participants had less knee pain and lower levels of a chemical indicator of arthritis. The takeaway? Squatting had reversed their condition and improved their knee joint health.
Another study published in the Scandinavian Journal of Medicine & Science in Sports asked 53 participants aged 70 or older to perform slow resistance exercises (squats, push-ups, and sit-ups) for three months. At the end of this period, they noted “an increase in thigh muscle thickness, knee extension strength, and hip flexion strength,” as well as positive changes in body composition (i.e., more muscle mass and less fat around the waistline)6. What’s interesting is that the only resistance involved in the exercises was bodyweight. This shows how impactful regular squatting can be, particularly among older folks who might be intimidated by the notion of slinging weight around.
Another bonus of bodyweight training is that it can be performed anywhere with no investment in equipment needed. This isn’t just a useful insight for the elderly, but for any age group. Whether you’re taking your kids to the playground, trying to fit in a quick workout in a hotel room, or waiting for a flight, you could get in a few air squats.
Sorting Out Your Squat
If you’re new to squatting, revisiting it after a long layoff, or eager to rebuild your squat, wall squats are a great way to start. The wall provides a consistent up-and-down path for the movement and a little support, which is perfect if stability is a concern. You can also start building in some isometric holds to begin building your leg strength.
Once you’ve got the wall squat down, you could move onto doing squats with a TRX Suspension Trainer. This removes the surface behind your back but still offers the support of the straps as you move through the downward and upward portions of your squat. You can also perform the air squats that have become a staple of CrossFit workouts over the past few years.
When you’ve nailed your form in an unweighted setting, it’s time to challenge your pattern with a little load. While back and front squats have a place in a more advanced squat program and are great ways to build muscle and develop strength and power, for novice to intermediate clients I prefer a goblet squat. Holding a dumbbell or kettlebell to your chest forces your body to get into a solid position to counteract the weight. Some people find it easier to get more depth in their squat with goblets than other variations.
How Low Should You Squat?
Which brings me to another component of the squatting debate: how low should you go? Old-school strength coaches usually favor the “ass to grass” method in which you try to get your butt close to your heels. There’s evidence to suggest that going this deep increases glute activation and if you have sufficient mobility, getting low is just fine. But many people start to excessively round their lower back with a deep squat, and if they have a pre-existing knee issue, it can start to cause or exacerbate pain. So what I’d suggest is that you go as close to parallel as you can.
Depending on your injury history, training age, and comfort level, you might end up a little below or above this, which is fine. If you have range-of-motion limitations, don’t despair. A study published in the European Journal of Applied Physiology found that while full-depth squats improved is “more effective for developing the lower limb muscles,” half squats still increased quad and hamstring strength7.
Another common question I get is, “How wide should my feet be when I squat?” While you could disappear down an internet rabbit hole in an attempt to get a definitive answer, I usually suggest placing your feet comfortable hip-width apart. Everyone’s a bit different anatomically, so you might find yourself going slightly wider or narrower than your training buddies.
No matter where you currently find yourself in your squatting journey, doing some kind of squat two to three times a week will help you be stronger, more powerful, and more mobile. And, contrary to popular opinion, it will help your knees rather than harming them, as well as improving the resilience of your hips and ankles and making your connective tissues (ligaments, tendons, etc.) more resistant to injury.
Here are a few squat variations to start introducing to your workouts:
Wall Sit w/ Squeeze
DB Goblet Box Squat
Miss part one of this series? Click HERE to catch up.
 Dan John, “I Will Just Share This With You, Part of One of My New Books,” available online at http://danjohn.net/2010/08/i-will-just-share-this-with-you-part-of-one-of-my-new-books/.
 RF Escamilla et al, “Biomechanics of the Knee During Closed Kinetic Chain and Open Kinetic Chain Exercises,” Medicine & Science in Sports & Exercise, April 30, 1998, available online at https://pubmed.ncbi.nlm.nih.gov/9565938/.
 RF Escamilla, “Knee Biomechanics of the Dynamic Squat Exercise,” Medicine & Science in Sports & Exercise, January 2001, available online at https://pubmed.ncbi.nlm.nih.gov/11194098/.
 Akito Yoshiko and Kohei Watanabe, “Impact of Home-Based Squat Training with Two-Depths on Lower Limb Muscle Parameters and Physical Functional Tests in Older Adults,” Scientific Reports, March 25, 2021, available online at https://pubmed.ncbi.nlm.nih.gov/33767255/.
 Zhihong Zhao et al, “Static Low-Angle Squatting Reduces the Intra-Articular Inflammatory Cytokines and Improves the Performance of Patients with Knee Osteoarthritis,” BioMed Research International, October 30, 2019, available online at https://pubmed.ncbi.nlm.nih.gov/31781657/.
 S Tsuzuku et al, “Slow Movement Resistance Training Using Body Weight Improves Muscle Mass in the Elderly: A Randomized Controlled Trial,” Scandinavian Journal of Medicine & Science in Sports, April 2018, available online at https://pubmed.ncbi.nlm.nih.gov/29247985/.
 Keitaro Kubo, Toshihiro Ikebukuro, and Hideaki Yata, “Effects of Squat Training with Different Depths on Lower Limb Muscle Volumes,” European Journal of Applied Physiology, September 2019, available online at https://pubmed.ncbi.nlm.nih.gov/31230110/.
Tim DiFrancesco, PT, DPT spent 6 seasons as the Head Strength & Conditioning Coach of the Los Angeles Lakers and is the founder of TD Athletes Edge. He is nationally renowned for his evidence-based and scientific approach to fitness, training, nutrition, and recovery for athletes and fitness enthusiasts.