Squatting to parallel or below will not hurt your knees provided you have the strength to control the movement.
I have two of the “Starting Strength” books (2nd & 3rd Editions) and they are great; probably the best strength books on the market. I was referred to the books by a “Sports Medicine” medical doctor who is a serious weight lifter and he believes in your explanations of proper techniques (means a lot for a medical doctor endorsing these books!). I have been an avid weight lifter all my life and for the past three years, have been working with my high school son (now 5-11, 200 lbs). I wanted to provide the best instruction for my son as he began strength training so I hired a friend, coach, and reputable trainer who has a master’s degree in physical education and specializes in “youth fitness.” I was impressed with him because he did not allow my son to do any lifting for over a month until he achieved the “appropriate flexibility” and body mechanics to lift safely (did plyometric and stretching work first).
With work, my son was able to achieve the “parallel squat” level (hip below patella). He uses your recommended form when doing squats (30 degree foot placement, knees always out, not rounded back, etc - form looks great!!). During this past year, his squat has developed to a deeper level, similar to what is describe “ass-to-grass” (photo on page 18 of 3rd Edition). I believe this has naturally occurred with increased improvement of body mechanics. He has no back or knee pain and this is his favorite lift; most comfortable with this full range of motion lift. He feels that trying to stop at the previous “parallel squat” position is short of his now full flexion and awkward (stopping short of where he feels full flexion.) He also uses a controlled rebound out of the bottom position (does not drop in a relaxed fashion, keeps tight; it is not a pronounced bounce, but is a noticeable “bounce” or rebound in the transition from down to up.)
His current high school football coach is not allowing him to do the full squats, telling him he is going to hurt his knees and back. The coach is having the players do squats which I would describe as “half-squats” or at best just above parallel squats. I obviously told him to listen to his coach, but we really want to know “what is right” since this has become a point of confusion for this young man. He has become very strong and one of the strongest players on the team (even though only at the end of sophomore year.)
Want to do the right thing and not get my son hurt - any comments or advise?
Squatting to parallel or below will not hurt your knees provided you have the strength to control the movement.
Cutting off heavy squats above parallel, on the other hand, can hurt the knees.
If you have read Starting Strength, you already know Rip's opinion on this matter. I assume you posted this to his Q&A and he transferred it here. Is your question, "Did Rip really mean what he wrote in his books?" Then the answer is, "Yes."
He does not specifically address "ass-to-grass" squats, but refers to "full squats" and "parallel squats". I realize he talks of full range of motion and does this include "ass-to-grass" squats if your body mechanics & strength allow it? This is the issue I am inquiring about.
Just below parallel is a "full squat" in the low bar position - it's where many people reach the end of their hamstring (and sometimes adductor) extensibility, beyond which the back must round if you're to go deeper. But even if this isn't the case with your son, going to just below parallel satisfies all the criteria of a full squat, and allows you to lift more weight than going ass to grass, which makes you stronger.
It sounds like the bounce you're describing may be the physical bounce of his hamstrings off his calves, which is not the same bounce that Rip discusses in the book.
In order for most people to do an ATG squat without back rounding, you would have to adopt a high-bar style of squatting, which is not what Rip teaches. Lots of great lifters use the HB squat though. There are many threads debating this on this and other forums, with both sides entrenched in their view.
A high-bar, "ass to grass" squat is not wrong, it is safe and it's a correct way to squat. It is not, however, the way Rip likes to teach the squat, for reasons made clear on the book. Your son's coach doesn't know jack shit and your son runs the risk of hurting himself under the supervision of such a moron. How to convince you son's coach to leave him the fuck alone, is your problem. You might go something like "I'm following the advice of a very renowned coach who wrote one of the most important books on the subject and I'd like my son to follow his advice, since he hasn't hurt himself until the present moment he should be fine. And more, at the end of the day, it's MY son, not yours." I'm sure you get the point, make sure to not imply that he's a moron (even though he is), just try to be nice and non-confrontational, for the sake of avoiding unnecessary conflict.
And if you want Rip to read a post, you have to post on his Q&A, he'll probably not see your post on the other sections.