Half Squat vs full ROM Squat
In most gyms today, a common instruction during squats, deadlifts, and lunges (as taught by many personal training organizations) is not to allow the knees to travel beyond the toes. Doing so will ultimately cause the destruction of your knees!
I do not agree. There are certain instances where partial range of motion (ROM) is indicated, but for the most part, I teach people the full squat for the following reasons.
FULL SQUAT BENEFITS
1 IT IS THE MOST PRIMITIVE MOVEMENT PATTERN KNOWN TO MAN
Our ancestors used to perform many daily functions (i.e. harvesting, gathering, hunting, cooking, eating, etc.) in a full squat position.
2 IN CASE ANYONE HASN'T NOTICED
We spend 40 weeks in the fetal position (which is basically a full squat) prior to entering this world - do we come out with bad knees?
3 WE SHOULD STRIVE TO TRAIN IN FULL ROM FOR EACH AND EVERY EXERCISE
The squat is no exception.
4 EVERY EXERCISE PRODUCES STRESS
The body then adapts to this stress.
5 CONTRACTION OF THE QUADRICEPS, HAMSTRINGS, AND GASTROCNEMIUS
MAINTAINS INTEGRITY IN THE KNEE JOINT
6 SHEERING AND COMPRESSIVE FORCES DO OCCUR AROUND THE KNEE JOINT
Sheering forces that occur in some open kinetic chain lower body exercises, such as the leg extension); however, the large contact area of the patella with the femoral groove (as knee flexion increases during the full squat) helps to dissipate compressive forces.