Weight loss is the #1 priority for a majority of gym goers, so it's no surprise that a certain amount of knee issues stem from stress due to too great a load on the joint.Typically each step you take places 2 times your bodyweight in impact on the knee, and each stride when running puts 4 to 6 times (no wonder that running is a horrible method of fat loss). Naturally it follows that knee health is going to be crucial for most people.
That should lead one to ask what exercises would then be best to address knee health while being efficient (i.e. hard). Single leg exercises such as lunges, single leg squats, and step ups are great, but for the purposes of this post I'll discuss the basic bilateral squat movement pattern.
We'll take it as a given that the squat is a fundamental exercises one should do for strength, weight loss, conditioning etc... and jump right in.
There has always been a fair amount of controversy over how deep to squat. Typically in the West doctors advise people not to squat deeper then parallel, if at all. But when one looks at how much trouble many older people have getting out of chairs I wonder if that common advice is based on an understanding of mechanics involved or just an outdated notion (hint: outdated).
Needless to say if you have orthopedic issues than by all means only squat as far as you are able to pain free, and follow what your physical therapist/physician recommends. And of course hip mobility/flexibility and back health are part of the equation - only more reasons why we all need to be doing hip mobility work. But I'll save that for another post.
Having lived in Japan I can tell you it's not uncommon to see 70 year old people squat ass to grass for hours per day. While in America where we tend to sit in chairs and almost never squat it's rare to find someone that can hold a full squat for even a minute - and it's often those same people that tend to have joint issues.
Digging into the research, a physical therapist friend said she had come across research indicating that full range of motion (ROM) squats actually promoted hyaline cartilage health. Cartilage is the tough connective tissue that is between the bones, which when worn down produces osteoarthritis (pain produced by bone on bone contact). Doesn't sound like fun to me.
One theory is that moving the joint through it's full range of motion helps keep the connective tissue lubricated. Cartilage is formed through the laying down of collagen protein. Conversely a knee injury often results in a decrease lubrication, which according to studies results in a higher risk of arthritis.
Another factor to look at is strength. Consider the following:
Take, for example, the quadriceps, the large muscles on the front of the thighs that help raise and lower the legs. "It's common knowledge that patients with osteoarthritis of the knee will have weakness in the quadriceps," says Dr. Kenneth Brandt, a rheumatologist at Indiana University in Indianapolis. For a long time, physicians assumed this was because their patients' pain prevented them from exercising. But five years ago, Brandt and his colleagues began studying a group of 400 elderly people living in central Indiana and discovered, much to their surprise, that weakness in the quadriceps in some cases preceded the advent of osteoarthritis.
In other words the stronger your leg muscles are, the less stress put on the joint - which saves wear and tear on cartilage. To add to that, in the process of getting your legs stronger if you are moving your joints through a full range of motion, as in a full squat, your cartilage will be better lubricated.
Another interesting fact is that Olympic lifters, who are known for extremely deep squatting, tend to have less knee injuries than bodybuilders, who often use exercises that isolate the knee joint such as the leg extensions.
The goal of Olympic lifters is to be as strong as possible and not aesthetics, so they stick to exercises that get the job done efficiently (no machines). However, a byproduct of that training is extremely well developed legs and healthy knees.
Thus when you are in the gym leave your ego at the door and use an empty bar if that's what you can squat. It will be better in the long run in order to build strength and protect your knees by going through a full range of motion.
So the next time some dude half squatting 135 tells you deep squatting is bad for you just refer him to 'ol Vencelas Dabaya here front squatting 440lbs for reps. By the way he weighs around 160 lbs.