TL;DR: Squats are usually touted as being bad for the knees, but this is not the case. In fact, squats may even be good for your joints and health.
I often come across the notion that squatting is damaging to the knees. It's plastered over forums and even doctors recommend against the squat in some situations.
Squatting is one of the most basic exercises we can do, it occurs every where in daily life. But are squats actually bad for your knees?
To answer this, we first need to ask a few more questions.
Table of Contents:
Is Compression Risky?
The first reason people claim against squatting is that it causes compression. If you execute heavy squats on a regular basis, the cartilage will eventually wear out and become damaged.
This makes sense since the higher the load in a squat, the higher the compressive pressures at the knee joint. (1)
Ligaments, tendons, and muscles have the capacity to withstand high stresses, repair, and adapt.
Other parts of the knee structure can distribute part of the compression and protect against shear pressures. Not only that, but cartilage has excellent stress absorption capabilities.
Your body is able to adapt over time. Building muscle, improving neuromuscular control, increasing tendon and bone thickness, and improved cartilage resilience are all examples of adaptations made by the body when under a resistance training program.
Although the body may be resilient, the combination of repetitive compression, shear, and twisting forces may be problematic for the knee joint. (2)
This is where we must look into squat depth.
Ideal Squat Depth
The ideal squat depth varies massively. If you're a powerlifter, you must squat deep, below the knees, for the squat to count in a competition.
You must be comfortable catching a clean or snatch in a deep squat posture if you are a weightlifter or cross fitter. Squatting deep may not be worthless, though.
Individuals who do deep squats have a minimal risk of injury. Some lifters often train 10 times a week at the professional level.
Knee injuries are rare, regardless of age, despite the heavy load of deep squats.
Injury rates were found to be around 0.0017 per 100 training hours in a study of 13-16-year-old weightlifters, which is lower than most popular sports like basketball (0.30), track and field (0.57), football (0.10), and gymnastics (0.10). (3)
Why Is This?
At 90° of knee flexion, compressive forces below the knee cap and compressive stress in the knee joint are highest.
The quadriceps tendon and the knee joint make significant contact at 90°, which helps to distribute the weight and stress.
Another factor to consider is how much weight you can squat while bending to 90°. The deeper the squat is, the more difficult it is to raise heavy weight.
Is it more dangerous to increase weight and decrease squat depth, or to keep the weight small and squat deep?
Once again, it is dependent on your body's adaptation throughout the course of your workout. The contact area of the bones inside the knee joint decreases while doing deep squats.
If the development has been slow enough for such tissues to acquire resilience, you may depend more on the force transmission and protective actions of surrounding ligaments and muscles.
Between 80° and 100° of knee flexion, the compressive forces are highest.
When transitioning from the lowering to the standing phase of the squat, the forces reach their dynamic peak. (4)
Another thing to think about is the speed. The quicker you fall and transition to standing, the higher the compressive pressures will be, which may even reach up to 24x your body weight.
Stresses
The findings of evaluating knee joint cartilage in weightlifters are usually favourable. (5)
Squatting heavy weights regularly may benefit the spine as well. When comparing weightlifters to sedentary people, researchers discovered that weightlifters had less spine deterioration. (6)
People who exercise and load their knees regularly have less deterioration than controls. Over time, cartilage, tendons, and muscles have a higher mechanical tolerance to stress. (7)
However, this research is not yet conclusive. This isn't to say that degeneration won't happen, but it won't be due to compression.
Overtraining or sedentary behaviour, poor nutrition, insufficient sleep, and high stress levels are all more likely to induce knee deterioration than regular deep squats.
However, as your tolerance and resilience improve, you can still control numerous squat factors.
Understanding the variables that affect compression enables us to modify squats appropriately.
Keep the weight low and aim for a depth that is near to parallel. Slow and controlled speeds, such as 3-4 seconds for the eccentric and 1-2 seconds for the concentric, is recommended.
Are Squats Bad for the Knees?
Doing a squat is one of the most beneficial exercises you can do. The bodyweight squat is great, but it becomes a complete body workout when you add resistance, such as in the barbell squat.
Your body is resilient and can resist, repair, and adapt to a variety of stresses, including heavy loading in the form of resistance exercises.
Studies suggest that the squat is in fact safer than many popular sports, such as basketball and football.
Therefore, the squat is not bad for the knees, in fact, doing the squat can be very beneficial for your health, providing the correct form is used.
Conclusion
If you are adding the squat into your workouts, I recommend squatting with a moderate weight (8-12 reps to near failure) and to parallel, not too deep but not too high.
Remember to always have a training parter with you as a spotter if you do any heavy free weight movements such as the squat.
Always use the correct form, the correct gear, and follow the proper safety advice, such as using a squat rack with safety bars.
> Check out our completely free 15 day squat challenge. Your glutes, hamstrings, quadriceps, and calves will all benefit from this squat program.
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References
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This evidence based analysis of the effect of squatting on knee health features 7 references, listed below.
1. Wallace DA, Salem GJ, Salinas R, Powers CM. Patellofemoral joint kinetics while squatting with and without an external load. J Orthop Sports Phys Ther. (2002, Apr) (Comparative Study) ✔
2. Miller RH, Edwards WB, Brandon SC, Morton AM, Deluzio KJ. Why don't most runners get knee osteoarthritis? A case for per-unit-distance loads. Med Sci Sports Exerc. (2014, Mar) (Comparative Study) ✔
3. Hamill, Brian P. Relative Safety of Weightlifting and Weight Training. Journal of Strength and Conditioning Research. (1994, Feb) ✔
4. Hartmann H, Wirth K, Klusemann M. Analysis of the load on the knee joint and vertebral column with changes in squatting depth and weight load. Sports Med. (2013, Oct) (Review) ✔
5. Gratzke C, Hudelmaier M, Hitzl W, Glaser C, Eckstein F. Knee cartilage morphologic characteristics and muscle status of professional weight lifters and sprinters: a magnetic resonance imaging study. Am J Sports Med. (2007, Aug) ✔
6. Vadalà G, Russo F, Battisti S, Stellato L, Martina F, Del Vescovo R, Giacalone A, Borthakur A, Zobel BB, Denaro V. Early intervertebral disc degeneration changes in asymptomatic weightlifters assessed by t1ρ-magnetic resonance imaging. Spine (Phila Pa 1976). (2014, Oct 15) ✔
7. Roos EM, Dahlberg L. Positive effects of moderate exercise on glycosaminoglycan content in knee cartilage: a four-month, randomized, controlled trial in patients at risk of osteoarthritis. Arthritis Rheum. (2005, Nov) (Randomised Controlled Trial) ✔
✔ Citations with a tick indicate the information is from a trusted source.
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