Myth #1: The Knee Shall Never Cross The Line Of The Toe
Every new trainer loves to spout this one off as a display of his or her biomechanical knowledge. They constantly scour the gym-goers movements on a noble quest to ensure patellar safety across the land. Unfortunately this unsubstantiated notion is perpetuated and accepted as fact in gyms everywhere. These are the same trainers that allow a gross deviation of the patella to the medial or lateral aspect during an exercise (the knee pointing a different direction than the foot), which actually is dangerous and degenerative.
If one were to assess knee injuries in athletic (read as: sport) environments, it becomes apparent that a high percentage of patellar trauma cases are sustained while the knee is beyond the all-sacred toe-line. In a misguided attempt to avoid knee injuries, the exercise community has therefore made this knee position taboo. In reality, the opposite reaction would have been preferential. Since this knee position is unavoidable in sports, or even in everyday life (try walking up or down stairs or a hill without your knee crossing your toe line) the proper way to prevent injuries is to strengthen the musculature around the joint by allowing the knee to travel into the “unsafe� zone in a controlled environment.
All joints contain feedback mechanisms inside the connective tissue and joint capsules called proprioceptors. These communicate with your nervous system to tell your brain what position your joint is at. This is how you can close your eyes and be aware of exactly what angle all of your joints are at without actually seeing them. To simplify a complicated issue, the more time you spend with your knee past your toe-line, the more you teach your nervous system to activate the protective soft tissue around the joint therefore PREVENTING injury during athletic situations (Supertraining, Siff & Verkoshansky, 1993). Close your eyes and think of a highly succesful strength coach. Yep, he agrees. Somehow, this news just doesn’t buy column space in Muscle and Fatness.
So remember this - the “golden rule� that the knee should never cross the line of the toe during any type of lunging exercise should be buried in the ocean with the lost city of Atlantis. (Of course, if this position causes consistent pain, then you should avoid this particular variation of the exercise).
Myth #2: Full Squats (below parallel) Are Bad For The Knees
More squat myths?!?
We’ve all heard it, if you dip below parallel during a squat, your kneecap will blow off and land in the front desk girl’s mocha latte. Well it just ain’t true! What’s that, you need a little more evidence? Ok boys and girls, its time for today’s episode of Fun With Musculoskeletal Anatomy.
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, thereby relegating squat myth #2 to the fiery pits of hades.
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