Throttle said:
knees behind the toes is never a proper consideration for squat form, despite the conventional wisdom. i've seen a couple squat analyses that discuss this but I can't come up with one at the moment.
You could be looking for this. They do go over some, but there is a difference in a little bit, and how some people go so far forward they look like they are about to fall over. That is no good. I mean I try to get mine about right at the toe, but I dont ever do them farther back. And at the same time I dont have my whole knee way over my toe.
This description should help some............
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Torque Force
Contrary to propaganda to the contrary, prominent weight training authorities demonstrate the squat with the knees flexing forward at the same distance as the hips flex backwards. Fredrick Hatfield, Ph.D., the first man to squat over 800 lbs, recommends the knees to extend over the feet with the back more upright for quadriceps development. "Strength Training for Young Athletes" by Steven J. Fleck, PhD and William J. Kraemer, PhD, illustrate parallel squats with the knees extending beyond the feet (knees moving forward with same magnitude as hip moving backwards).
Torque force is necessary for the muscles and joint structures to adapt to the respected overload. If the knee does not travel forward during the barbell squat, the quadriceps muscles are not significantly exercised. On the other hand, injury may result if the knee or lower back experience greater torque forces than what they are accustom.
Fry et. al. (2003) examined the hip and knee torque forces of variations of parallel barbels squats and concluded appropriate joint loading during this exercise may require the knees to move slightly past the toes.
Try this simplified qualitative method in determining relative torque forces in the knee and hip joints. First take a photograph of the barbell squat in a full decent with a perspective perpendicular to the joints plane. Draw a line of force through the resistance on its center of gravity, straight up and down, parallel to the force of gravity. Gravity acting on both the body mass and added mass (barbell) contribute to the resistance. On the barbell squat, the center of gravity is between the forefoot and heel. If it is not, the individual will fall over, toward the center of gravity. Incidentally, compression forces act upon the joints during the squat stance.
During the execution of a barbell squat, the knees and the hips travel in opposite directions away from the foot, or away from the center of gravity. Draw a second line on the knee joint parallel to the line of force. Draw a third line on the hip joint parallel to the previous lines. A relative comparison can be made on the torque forces of the knee and hip. Typically the torque forces are similar for the knee and hip joints on the barbell squat; the knees travel forward the same magnitude as the hips travel backwards. Generally speaking, during a powerlift type squat (bar lower behind the shoulders and a wider stance) the knee does not travel forward as far as a bodybuilding type squat. The hips typically travel back further with the torso bent forward on a powerlift type squat. This emphasizes the stronger hip extensors and adductors and consequently reduces knee extensor involvement. Knee torque is further reduced by a wide stance.
I probably have a picture of what they are showing from either my Biomechanics book or one of the books I have, but unfortunately I can't draw it on here.
