squats below 90 and step ups with knee higher than hip...

[vancityrolla]

I know this has been talked about alot but if anyone could post any links to info it would be very helpful, I felt like an ass today trying to teach another PT a few things then he told me im doing them wrong... I was told today by a personal trainer that lower than 90 puts the knees at risk of injury and there is no need to go past 90. I knw this is a long debated topic so im sorry just looking for the newest information/study on this.. He has a HK degree and years of exp so its not just your avg trainer thats why I was sort of surprised when he told me low squats are bad for knees.
From everything I have read I agree for someone new to exercise yes they can be bad but for an athlete/exp lifter I dont think they are bad I personally have never had any problems and I can go very low without giving up my form. I see some people go low but they lean way to forward and have the knees track over to far that I can understand. But as long as you can keep your back straight and knees in line I dont see how they are bad for the knees if anyone can shine some light on this it would be great.
One more thing I was told hurt the knees is step ups where the step is higher than 90, so at the starting position your knee would be a few inches higher than your hip. again I would only do this with an athlete/exp person not a beginner this is another thing I have been doing for a long time with no problem but then im told its putting the knees at risk..
so im just looking for some info/feedback or different opinions on this

[bigballin6161]

Full squats are much safer. The knee is the most stable when it is straight or at full flexion. The knee is actually unstable at the 90 degree point. Also doing deep squats hit the VMO which is essential for knee stability. Doing squats to 90 degrees is actually bad for the kness. Step ups above the hip are good too (triple jumpers step up) The problem is you cant start with them as you must progress to properly strenthen the VMO properly. If the vmo can handle it then sure you can go higher as long as you are upright and not leaning forward. Tell him to STFU.

[Debesq]

As long as your knees aren't tracking over your toees, stress on your knee ligaments will be minimal. Depth is not really an issue.
Any squatting depth is safe, as long as you emphasize keeping the knees from going too far over the toes and spine stability isn't sacrificed(so no butt-winking). For some clients with mobility issues this will be way above parallel. For others it could be almost ass to calves. Just use good judgement.

Edit-Never use the term "90 degrees" as this is usually never synonymous with actually squatting to parallel. Only in powerlifters who sit way back into their squat(keeping their shins vertical) will these be the same thing. I see people squatting to 90 degree knee flexion all the time; These people are usually squatting way above parallel with their knees far out over their toes. Definitely not what you want your clients doing.