For years it has been advised that your knees should not travel past your toes when performing a squat due to excessive strain placed on your knees and an increased risk of injury. However, research has shown that your knees are perfectly capable of handling this pressure and the stress placed upon it is actually what reduces the risk of injury.
If a person already has anterior knee pain then yes, putting more pressure on the knee may not be the best idea as this would only cause more pain, therefore hindering adherence to exercise and diminishing results. However, generally speaking, allowing your knees to travel past your toes is not a problem (if anything, it is the normal way to squat). Think of how a child squats to play with their toys. A child has not been affected by the unnatural position our body is in when sitting in a chair. Instead their resting position is a squat and they are able to maintain this position for lengthy periods. Their squat is perfect and part of that is their knees travel past their toes. Allowing your knees to travel past your toes ensures your centre of gravity is kept within your base of support.
One study which may have contributed to this false-belief is Fry et al., (2003) who found that restricting forward knee translation reduced peak knee torque by 22%. This is all well and good, but by reducing the load on the knees you are only placing it elsewhere. Although there was a 22% reduction in knee torque, there was a 1070% increase in hip torque. I’ll say that again for the people in the back – 1070%! That’s a massive load for the hip (and lower back) to handle. No wonder so many people complain of hip and back pain when squatting! Some may even begin to feel knee pain due to overloading of the glutes and hamstrings leading to reduced quad strength proportionate to hamstring strength. Although anterior knee stress increases as the knees come forward during a squat, Schoenfeld (2010) identified that the knee is perfectly capable of enduring this stress.
Hopefully we can start to set the record straight! Knees travelling past toes is a normal and healthy movement pattern and not dangerous and injurious.
By Nicholas Dimos (Physiotherapist)