There is a lot of confusion surrounding the terms pronation and supination. These words are thrown around with impunity by the sport shops and other medical professionals, but there still seems to be a lack of understanding about what they really mean.
Pronation and supination describe normal movements of the foot that are essential for foot function.
Everybody Pronates and Supinates. These are normal and essential movements. The amount which we Pronate and Supinate is dictated by the inherited structural mal-alignments and acquired muscle imbalances that we each uniquely have. It is when these motions become excessive that the potential for problems arises. A foot that works at its maximum range of motion…ie. Maximally pronated, will come under strain, that can predispose the foot to trauma, and injury.
The foot ideally should at one point of the walking cycle be a loose adaptor, adapting to uneven surfaces and absorbing shock and at another point, a rigid lever for propulsion.
The normal foot strikes the ground a little laterally, or supinated, then the foot moves into pronation and becomes a loose adaptor and shock absorber. The tibia (leg) at this point is rotating internally. Just after this phase has finished and the foot has absorbed shock, the tibia starts to de-rotate (external) as the foot re-supinates, creating a higher arch and a stiffer lever for propulsion, heel lift off and toe off. There is a timing involved in the foot that when it works, the foot functions with efficiently, and the muscles of the foot have no need to overwork at all.
Should this timing not be achieved, for whatever reason ie: muscle-imbalances, structural mal-alignment, leg length discrepancies, the potential exists for a large range of problems. In children it can effect growth and development, co-ordination, balance which can impact on sport performance and willingness to participate. in adults, it can lead to a whole array of musculo-skeletal complains all the way up the back and neck. Sports injuries, arthritis, tendonitis etc.
Add in to mix, incorrect footwear, weight gain, occupations that involve standing or sitting a lot, you then have the recipe for long term foot, knee, hip and back problems.
The foot however does not exist in isolation and it is influenced by problems that may exist elswhere in the body. The Pelvis plays a major role in symmetry between the two sides of the body. Most of us have some sort of Pelvic Torsion, or twist. This can lead to a functional scoliosis, leg length differences muscle imbalances, feelings of tight muscles, weak core . Gait imbalances caused by Pelvic anomalies can lead to one foot behaving differently to the other . The feet try to help the body gain equilibrium by adjusting arch height.