Pronation occurs at the joint below the ankle, the subtalar joint. It describes the inward rolling motion of the foot just after it lands on the ground. This moment is called initial contact, which is part of the stance phase of the gait cycle.
When you walk or run, pronation helps to attenuate the shock of initial contact. Without it, the full impact of each step would be transmitted up the leg and affect the normal mechanics of the lower limbs. Besides acting as a shock absorber, pronation also helps the foot 'recognise' what type of ground it is on by stabilising and adjusting the foot to the terrain type.
Running shoes are designed today specifically for different pronation patterns. When you pick your next pair of running shoes, your pronation type is a very important factor in your choice.
The best way to find out how you pronate is to consult an expert, who will perform a Gait Analysis and then advise you on the best type of running shoes for your pronation pattern. Many experts will ask to see your old pair of trainers, as their wear pattern gives an indication of the way you pronate. Of course, other factors than pronation, such as weight, also play a role in choosing the best shoe.
You are likely to be a neutral pronator if the soles of your shoes show wear in an S-shaped pattern, from the outer (lateral) heel to the big toe. When you have a normal pronation pattern you can run in a wide variety of shoes, but specialised neutral running shoes offering cushioning and support are most suitable. The GEL-NIMBUS is the leading cushioning model for neutral runners.
Pronation pattern of a neutral runner
Underpronation, also known as supination, is when the foot doesn't pronate much. The outer or lateral side of the heel hits the ground at an increased angle, and little or no normal pronation occurs, resulting in a large transmission of shock through the lower leg. This lateral loading of the foot continues for the entire stance phase of gait, further affecting running efficiency.
Underpronation (also known as supination)
Underpronators (or supinators) are likely to have excessive wear on the outer heel of their shoes, and the entire upper may be pushed over to the lateral side.
As underpronators tend to be susceptible to shock-related injuries like stress fractures, you should choose a neutral running shoe with plenty of cushioning, for example the GEL-CUMULUS. The extra cushioning will lessen the impact of landing the legs have to endure when running. Underpronators should avoid shoes with dual density midsoles, such as DuoMax, since they tend to exaggerate the problem.
Overpronation is when the foot rolls in excessively, or at a time when it should not, for instance late in the stance phase of gait. In this case much weight is transferred to the inner or medial side of the foot, and as the runner moves forward the load is borne by the inner edge rather than the ball of the foot. This destabilises the foot, which will attempt to regain stability by compensating for the inward movement. In a kind of chain reaction, this in turn affects the biomechanical efficiency of the leg, especially the knee and hip.
The shoes of an overpronator will show extra wear on the inside of the heel and under the ball of the foot, especially the big toe.
Overpronators should consider choosing maximum support or structured cushioning shoes. Structured cushioning shoes provide a degree of stability and cushioning, whereas maximum support shoes are the most stable shoes you can get. Running shoes in both of these categories will help your feet distribute the impact of running more effectively. The GEL-KAYANO is a leading structured cushioning shoe, whereas the GEL-FORTE and the GEL-FOUNDATION are reliable models in the maximum support category.
Acknowledgements: This article has been written under the guidance of Brice Newton, Footwear Product Manager at ASICS Europe, and Simon Bartold, ASICS International Research Coordinator.