How Low Should You Squat - Full or Half?
Whether squatting "ass to ground" (ATG or full squat) is more beneficial, or hazardous, than squatting with upper or lower thighs parallel to the ground (parallel or half squat) is a perennial question in weight training and weightlifting circles. Here is my view of it.
In ATG you go right down so that your butt is closest to the ground. This requires almost maximum flexion then extension of the knee joint under load as you lower then push "out of the the hole" to stand upright. With parallel and half squats you only go low enough so that your thighs are parallel to the ground or even higher with knee joints at about 90 degrees or a bit more. Even less flexion is sometimes called a quarter squat.
The first thing to note is that if you do Olympic lifting -- snatches, and clean and jerks -- the ATG or full squat is a part of the formal lift protocol and technique that you need to learn.
Beyond that, there is a common belief that ATG squats are superior to parallel or half squats because the full range of motion promotes balanced and superior muscle and strength development. The implication is that parallel squats don't involve the hamstrings and gluteus (butt) muscles like full squats and therefore you get a muscle strength imbalance between the quadricep muscles at the front of the thigh and the posterior chain, which includes the hamstrings and the glutes. This belief seems to be widespread because it's repeated regularly.
I could find no justification for this position. In studies of muscle activation comparisons between half and full squats, the main hamstring muscle, the biceps femoris, is involved almost equally in full or half squats. The main butt muscle, the gluteus maximus, is involved slightly more in the full squat but full squats are likely to utilize less heavy weights so that any general advantage in muscle or strength development may be minimal for full squats. And somewhat contrary to widespread opinion, the rectus femoris muscle of the front of the thigh -- in one study at least -- got hammered twice as hard in the ATG squat as the parallel squat. Muscle imbalance development with parallel squats is unlikely to be a problem. In this context one could almost argue that full squats are more likely to cause muscle imbalance by emphasizing the rectus femoris compared to the posterior chain.
Finally, some sports medicine authorities claim that full squats can damage the knees. Experienced Olympic lifters tend to dispute this claim -- they have the experience to know -- and there is little medical evidence to support the idea that full squats are inherently dangerous. Even so, there are additional compression forces involved in full squats, so for novices starting out, or for people who have less than ideal biomechanical knee joint structure or pre-existing injury, caution is warranted. But that goes for any exercise, including parallel squats. If it hurts, don't do it. Proper form and technique is paramount for injury prevention.
Summing up, there are few compelling reasons to exclude either full or half squats from your program. Naturally if you train for Olympic lifting you will need to do full squats. I mix it up by doing both.
Photo by Ryan McVay / Getty Images
Sources:
J Strength Cond Res. 2002 Aug;16(3):428-32. The effect of back squat depth on the EMG activity of 4 superficial hip and thigh muscles. Caterisano A, Moss RF, Pellinger TK, et al.
12th Annual Congress of the ECSS, 11–14 July 2007, Jyväskylä, Finland. An electromyographic analysis of four methods in squat training. Sogabe Akitoshi (Konan University, Japan)
Comments
While this article is well written, it is incorrect. To say that half squats involve the hamstring and glutes nearly as much as full squats is incorrect. Also you neglected to mention the danger it poses to your knees by placing the all the stress of stopping the weight’s momentum with the knee joint.
Cameron, you may disagree, but the evidence suggests I am correct. If you explored the references at the bottom of the article, including the linked one, you will see some experimental confirmation of what I wrote. If you have some evidence to the contrary, please post it here. On what basis do you base your beliefs?
Regarding injury to the knees with half or parallel squats, do you also believe that power cleans and power snatches are injurious to the knees? There is no medical evidence for this, of which I am aware, based on any reasonable program of squats. Again, please post your sources.
Thanks, Paul Rogers
Cameron, you may disagree, but the evidence suggests I am correct. If you explored the references at the bottom of the article, including the linked one, you will see some experimental confirmation of what I wrote. If you have some experimental evidence to the contrary, please post it here. On what basis do you base your beliefs?
Regarding injury to the knees with half or parallel squats, do you also believe that power cleans and power snatches are injurious to the knees? There is no medical evidence for this, of which I am aware, based on any reasonable program of squats. Again, please post your sources.
Thanks, Paul Rogers
Regarding power cleans/snatches vs full cleans/snatches. The load on power cleans/snatches is much less that the load used in full atg cleans/snatches, so no, power versions are not injurious to the knees. Try the load used in a full clean/snatch for a power movement and you’ll definitely feel the stress on your knees.
sorry it took me so long to get back, been busy lifting and working. as for sources here you go:
The knee has four main protective ligaments that keep the femur from displacing on the tibia (ACL, PCL, MCL, LCL). These four ligaments are most effective at their protection during full extension and full flexion. Full extension would be when you are standing; full flexion would be when there is no daylight between your hamstring and your calf. When the knee is at 90 degrees of flexion (the halfway point), these four ligaments are almost completely lax and cannot exert much if any of a protective force at the knee (Zatsiorsky V. Kinematics of human motion. 1998 - published by Human Kinetics - p.301). Unfortunately, the position where the protective ligaments of the knee are not doing any protecting is the common recommended stopping point of a squat. Therefore, as it as it turns out, this is the exact worst place you could reverse the motion under load. If flexibility allows (heels staying planted, torso not flexing forward past 45 degrees), then a full squat where you lower yourself all the way to the ground is far safer on the knees than the traditional half squat. Guess what joint angle most leg extension machines start at? If you said 90 degrees, give yourself a pat on your healthy knee. This makes a full squat even safer than a leg extension machine (Wilk K et al. A comparison of tibiofemoral joint forces and electromyographic activity during open and closed kinetic chain exercises. Am J Sports Med; 24(4):518-527).
So am I telling you never to do parallel squats? No! Am I saying that you’ll injure yourself on a parallel squat? No, again! What I’m trying to do is simply make an argument for the safety of full squats.
sorry it took so long for me to get back. But here you go: The knee has four main protective ligaments that keep the femur from displacing on the tibia (ACL, PCL, MCL, LCL). These four ligaments are most effective at their protection during full extension and full flexion. Full extension would be when you are standing; full flexion would be when there is no daylight between your hamstring and your calf. When the knee is at 90 degrees of flexion (the halfway point), these four ligaments are almost completely lax and cannot exert much if any of a protective force at the knee (Zatsiorsky V. Kinematics of human motion. 1998 - published by Human Kinetics - p.301).
Unfortunately, the position where the protective ligaments of the knee are not doing any protecting is the common recommended stopping point of a squat. Therefore, as it as it turns out, this is the exact worst place you could reverse the motion under load.
If flexibility allows (heels staying planted, torso not flexing forward past 45 degrees), then a full squat where you lower yourself all the way to the ground is far safer on the knees than the traditional half squat. Guess what joint angle most leg extension machines start at? If you said 90 degrees, give yourself a pat on your healthy knee. This makes a full squat even safer than a leg extension machine (Wilk K et al. A comparison of tibiofemoral joint forces and electromyographic activity during open and closed kinetic chain exercises. Am J Sports Med; 24(4):518-527).
So am I telling you never to do parallel squats? No! Am I saying that you’ll injure yourself on a parallel squat? No, again! What I’m trying to do is simply make an argument for the safety of full squats,
Cameron, thanks for spending the time to analyze this issue.
We agree then. For the most part, there’s no evidence either way that full or half or parallel squats injure healthy knees.
However, I disagree with your statement that “a full squat where you lower yourself all the way to the ground is far safer on the knees than the traditional half squat.”
There is absolutely no medical evidence for that statement either.
Thanks, Paul Rogers
So, this is a bit of a vanity question:
I was under the impression that if you could squat to the depth where you could put your butt in a chair (upper thigh parallel to the floor), that you were doing a full squat–and could claim that weight.
Reading this article then, it appears I’ve been doing half-squats? I don’t think I’ve ever seen anyone do a full ATG squat, unless it was the Olympics.