Pronation is the way the foot rolls inward when you walk and run. It is part of the natural movement that helps the lower leg deal with shock. Some people pronate more (overpronation) or less (underpronation) than others. Though this is not bad in itself, it does affect the way you run and it may increase the likelihood of injury. This makes your pronation pattern an important factor in choosing the right running shoes.
Pronation
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.
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.
Pronation pattern of a neutral runner
Underpronation
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. The extra cushioning will lessen the impact of landing the legs have to endure when running. Underpronators should avoid shoes with dual density midsoles, since they tend to exaggerate the problem.
Overpronation
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.
Overpronation
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.
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.
Source: asics.co.uk/running/knowledge/understanding-pronation/
