Supination is a movement at the foot which is a necessary movement for walking and running amongst other activities. However, in some cases over-supination can become a problem which leads to injuries.
What is supination?
Supination is the natural movement of the foot as it rolls out during the gait cycle. In particular it is the movement of the subtalar joint (between the talus and calcaneus) into inversion, plantar flexion and adduction.
Inversion is where the sole of the foot is turned inwards, plantar flexion is where the foot and toes point downwards and adduction of the ankle involves the toes pointing across the body. Combine all three movements and you have supination.
When standing, supination occurs as the foot rolls outwards, placing most of the weight onto the outside of the foot and raising the arch. Supination is a normal part of the gait cycle (walking/running) which allows the foot to form a rigid structure for propulsion.
The opposite movement to supination is pronation, this is also a normal part of the gait cycle and when excessive is termed overpronation.
What is oversupination?
Oversupination also called hyper-supination is far more rare than overpronation and causes problems for runners and other athletes, as in this position the foot is less able to provide shock absorption. It therefore predisposes the athlete to:
Supination and sports injuries
Over supination usually causes over-use type injuries, occurring most frequently in runners. A foot which oversupinate's, underpronates. Pronation allows the foot to absorb shock and mould to the surface of the ground. Therefore in oversupinated feet, shock absorption is reduced. The stresses normally absorbed by the foot are then passed up the lower limb.
Oversupination also causes an increased external (lateral) rotation force to be placed on the shin, knee and thigh which places additional stress on the muscles, tendons and ligaments of the lower limb.
How can I tell if I oversupinate?
Firstly, look at your feet when standing. Is there a high arch on the inside of the foot?
Secondly, look at your running shoes. If they are worn on the outside of the sole, especially on the forefoot area, then supination may be excessive when you run
Thirdly, try the wet foot test. Wet your feet and walk along a section of paving and look at the footprints you leave. A normal foot will leave a print of the heel, connected to the forefoot by a strip approximately half the width of the foot on the outside of the sole
If supination is a problem, the prints of the heel and forefoot will be connected by only a thin strip on the outside, or may not even be connected, as shown opposite
Gait analysis where your running style is assessed on a treadmill or forceplate by a suitable qualified professional will highlight if you overpronate, oversupinate or have a neutral gait. Most podiatrists, physio's and sports therapists will offer this service, as do some specialist sports shops.
For over supination you need a highly cushioned and flexible running shoe to make up for the lack of shock absorption at your foot. Visit a specialist running shoe shop where they can look at your feet and running style and advise on shoes for supination.
For people with considerable over supination, another option is to have an orthotic device or othotic insole fitted. Orthotics and insoles come in many types and prices. Some are pre-molded and can be bought off the shelf. These are ok for the majority of problem feet. However some cases may require specially casted orthotics from a relevant sports injury therapist or podiatrist. You wouldn't build a house without getting the foundations right so why do it with your body?