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.
Unless there is a severe, acute injury, overpronation develops as a gradual biomechanical distortion. Several factors contribute to developing overpronation, including tibialis posterior weakness, ligament weakness, excess weight, pes planus (flat foot), genu valgum (knock knees), subtalar eversion, or other biomechanical distortions in the foot or ankle. Tibialis posterior weakness is one of the primary factors leading to overpronation. Pronation primarily is controlled by the architecture of the foot and eccentric activation of the tibialis posterior. If the tibialis posterior is weak, the muscle cannot adequately slow the natural pronation cycle.
Common conditions seen with overpronation include heel pain or plantar fasciitis, achilles tendonopathy, hallus valgus and or bunions, patellofemoral pain syndrome, Iliotibial band pain syndrome, low back pain, shin splints, stress fractures in the foot or lower leg.
You can test for pronation by looking at the leg and foot from the back. Normally you can see the Achilles Tendon run straight down the leg into the heel. If the foot is pronated, the tendon will run straight down the leg, but when it lies on the heel it will twist outward. This makes the inner ankle bone much more prominent than the outer ankle bone.
Non Surgical Treatment
Fortunately, there are simple things you can do to cure and correct your overpronation issues. Certain exercises help. Pull your toes back using a rolled up towel. Roll your feet over a golf or tennis ball for a minute. And do calf raises by standing up and lifting up on your toes. These all help reposition the foot and strengthen the muscles and tendons necessary for proper support. Beyond that, simple adjustments to footwear will help immensely.
Strengthen the glutes to slow down the force of the foot moving too far inward. Most individuals who over-pronate have weak glute muscles and strengthening this area is a must. A simple exercise to strengthen glutes is lateral tube walking across a field/court/room. Place a lateral stretch band around your ankles and move your leg sideways while keeping your feet forward.