Question - Are deep squats bad for the knees?
Deep, controlled squats not only are NOT "bad for the knees", they are, in fact, good for the knees. Properly performed, they evenly and proportionately strengthen all muscles which stabilize and control the knee (in addition to strengthening the muscles of the hip and posterior chain, upper back, shoulder girdle etc). When the hips are lowered in a controlled fashion below the level of the top of the patella, full hip flexion has occured, and this will activate the hamstrings and glutes. In doing so, the hamstrings are stretched at the bottom of the motion and they pull the tibia backwards (toward da' butt) which counteracts the forward-pulling force the quadriceps apply during the motion. As a result, the stress on the knee tendons is lessened since the hamstrings assist the patellar tendon in stabilization of the knee. A muscle supporting a tendon which supports the kneecap is going to be better than the tendon having to take up the entirety of the strain by itself.
Think about Olympic lifters. They squat VERY deep (almost ridiculously deep) all the time, frequently 5 or 6 times weekly, with very heavy weight. If deep squats were so bad for their knees, they wouldn't be able to squat that deep, that often, and that heavy.
Partial squats, however, will NOT activate the hamstrings, and the amount of shearing force on the patellar tendon increases exponentially. What WILL happen if you do partial squats is that your quadriceps will become disproportionately strong as compared to your hamstrings, and the following are likely results:
1) In partial squats, the hamstrings aren't activated, which means the patellar tendon takes up all the strain/stress/pull during squats. As a result, fatigue and damage to the tendon can accumulate because tendons recover MUCH slower than muscles. Any type of action involving knee bend can then cause further stress and strain during daily activity. This is asking for trouble. If the hamstring is strong, it drastically reduces the amount of stress on the patellar tendon. Full squats make the hamstrings strong. Partial squats allow the hamstrings to become weak. Weak hamstrings are bad Bad BAD.
2) Partial squats develop the quads and neglect the hamstrings. Weak hamstrings coupled with strong quads result in hamstring pulls while sprinting, starting or stopping suddenly, playing sports, etc.. They frequently occur as the result of muscular imbalances across the knee joint. Strong quadriceps and weaker hamstrings result in a knee joint that is unstable during rapid acceleration and slowing, and the hamstrings are unable to counteract the powerful forces that occur during sudden stops and starts. In other words, you do a sprint with extra-strong quads and weak hammies, and you are begging for a pulled hamstring because your hamstring isn't as strong as the quads and isn't able to perform an adequate eccentric contraction to keep your knee joint from hyperextending during a sprint. As a result, you strain the hamstring because, although it isn't strong enough to do the job, it will hurt itself trying.
3) In sports, your acceleration will be weak, as will your jumping ability, as a result of underdeveloped hamstrings and hips. Poor speed/acceleration = poor performance
4) You will end up using stupidly heavy weights in the partial squat due to the mechanical advantage afforded by partial squats, and you put your back and even shoulder girdle at risk due to the extreme loading of the spine.
Quote:
Mark Rippetoe zei:
If it's too heavy to squat below parallel, it's too heavy to have on the back.
Besides, everytime you do partial squats, Jesus kills a kitten. Don't be a pussy, save the kittens. Squat deep.
'fo sho..Kvoel het nog altijd van gisterenavond..