Pronation occurs as weight is transferred from the heel to the forefoot and the foot rolls inwards. Or to put it a little more technically; pronation is the movement of the subtalar joint (between the talus and calcaneus) into eversion, dorsi flexion and abduction (turning the sole outwards, upwards and sideways). A certain amount of this is natural but it many people the foot rolls in too much or over pronates.
There are many possible causes for overpronation, but researchers have not yet determined one underlying cause. Hintermann states, Compensatory overpronation may occur for anatomical reasons, such as a tibia vara of 10 degrees or more, forefoot varus, leg length discrepancy, ligamentous laxity, or because of muscular weakness or tightness in the gastrocnemius and soleus muscles. Pronation can be influenced by sources outside of the body as well. Shoes have been shown to significantly influence pronation. Hintermann states that the same person can have different amounts of pronation just by using different running shoes. It is easily possible that the maximal ankle joint eversion movement is 31 degrees for one and 12 degrees for another running shoe.
Due to the laxity of the soft tissue structures of the foot, and the fact that the joints are not held together properly, the bones of the feet shift. When this occurs, the muscles that attach to these bones must also shift, or twist, in order to attach to these bones. The strongest and most important muscles that attach to our foot bones come from our lower leg. So, as these muscles course down the leg and across the ankle, they must twist to maintain their proper attachments in the foot. This twisting of these muscles will cause shin splints, Achilles Tendonitis, generalized tendonitis, fatigue, muscle aches and pains, cramps, ankle sprains, and loss of muscular efficiency (reducing walking and running speed and endurance). The problems we see in the feet, which are due to over-pronation include bunions, heel spurs, plantar fasciitis, fallen and painful arches, hammertoes, metatarsalgia (ball of foot pain), and calluses.
When sitting, an over-pronating foot appears quite normal, i.e. showing a normal arch with room under the underside of the foot. The moment you get up and put weight on your feet the situation changes: the arches lower and the ankle slightly turns inwards. When you walk or run more weight is placed on the feet compared to standing and over-pronation will become more evident. When walking barefoot on tiles or timber floors over-pronation is more visible, compared to walking on carpet or grass.
Non Surgical Treatment
Heel counters that make the heel of the shoe stronger to help resist/reduce excessive rearfoot motions. The heel counter is the hard piece in the back of the shoe that controls the foot?s motion from side-to-side. You can quickly test the effectiveness of a shoe?s heel counter by placing the shoe in the palm of your hand and putting your thumb in the mid-portion of the heel, trying to bend the back of the shoe. A heel counter that does not bend very much will provide superior motion control. Appropriate midsole density, the firmer the density, the more it will resist motion (important for a foot that overpronates or is pes planus), and the softer the density, the more it will shock absorb (important for a cavus foot with poor shock absorption) Wide base of support through the midfoot, to provide more support under a foot that is overpronated or the middle of the foot is collapsed inward.
Exercises to strengthen and stretch supporting muscles will help to keep the bones in proper alignment. Duck stance: Stand with your heels together and feet turned out. Tighten the buttock muscles, slightly tilt your pelvis forwards and try to rotate your legs outwards. You should feel your arches rising while you do this exercise. Calf stretch: Stand facing a wall and place hands on it for support. Lean forwards until stretch is felt in the calves. Hold for 30 seconds. Bend at knees and hold for a further 30 seconds. Repeat 5 times. Golf ball: While drawing your toes upwards towards your shins, roll a golf ball under the foot between 30 and 60 seconds. If you find a painful point, keep rolling the ball on that spot for 10 seconds. Big toe push:
Stand with your ankles in a neutral position (without rolling the foot inwards). Push down with your big toe but do not let the ankle roll inwards or the arch collapse. Hold for 5 seconds. Repeat 10 times. Build up to longer times and fewer repetitions. Ankle strengthener: Place a ball between your foot and a wall. Sitting down and keeping your toes pointed upwards, press the outside of the foot against the ball, as though pushing it into the wall. Hold for 5 seconds and repeat 10 times. Arch strengthener: Stand on one foot on the floor. The movements needed to remain balanced will strengthen the arch. When you are able to balance for 30 seconds, start doing this exercise using a wobble board.