Niall Ryan discusses research he condiucted into muscle activation patterns in full versus partial depth squats.
A common misconception in training is that all healthy individuals should squat above parallel, and many believe that squatting marginally above parallel is the optimum depth at which any type of squat should be performed. It is further believed that a squat to full depth of flexibility can injure an athlete and provide excessive strain on the knee joint and its structure.
Williams, D (2012) discussed that by reaching ‘full depth’, the posterior chain musculature or in this case the hamstring group are activated significantly more than reaching partial depth, and in turn we see a demonstration of the co-contraction theory and reduced knee strain.
In support of the above article we set out to test this theory. We conducted a study using electromyography (hereafter EMG). EMG measures the electrical activity of a muscle, and gives us an understanding of how hard a muscle is working. Understanding the amount of muscle activity during a particular exercise or action can assist in knowledge of the correct technique and further help the training of the intended movement.
During our study we looked at a full depth squat (hip crease below parallel) and a partial depth squat and the corresponding muscle EMG of the quadriceps and hamstrings in order to determine which squat technique was optimal. Ideally, more hamstring activity in a below parallel squat meant that we would see less anterior tibial translation (tibia shifting forward). In the presence of these shear forces about the knee, the athlete risks miniscal cartilage damage and acl straining. Therefore it is ideal to reduce these forces.
Our study found a 19mV increase in hamstring EMG activity in a full depth squat. This 19mV represented a 25% increase in hamstring EMG activity from above parallel to below parallel. Proving that squatting below parallel increases hamstring activation and reduces anterior tibial translation.
Next time you go for a squat, if not for anything else, think of your knees and squat deep!
Niall Ryan
Bsc. Exercise and Sports Science
Level One Crossfit Trainer
Coach, Range of Motion
