• When you run, your foot normally strikes the ground at the outer part of the heel, then the rest of it makes contact with the ground, rolling inwards around 4-5% (normal pronation) to absorb the shock. It then lifts off with a push from the toes, as the ball of the foot leaves the ground.
• Overpronation is normally (but not solely) associated with flat feet, and the rolling-in of the foot happens more than the ideal 4-5% and leads to a less efficient shock absorption. The excessive twisting can cause pain in the ankle, foot, shin and knees, if you are not wearing proper footwear.
• Underpronation or supination is when the middle of the foot rolls-in less than 4% and leads to a smaller area of the foot making contact with the ground and poorer shock absorption. Most of the pressure of the lift off falls on the two smaller toes. This is also normally associated with a high-arched foot, which tends to be less flexible. This can lead to plantar fasciitis (a painful inflammatory condition).
Know your pronation levels
• Walk barefoot to and from a floor length mirror, or have someone observe your walk.
• Observe others’ feet as they walk or run, and educate yourself on their ‘rolling-in’.
• Look at the bottom of your old running shoes—six months or older—and if you see the inner side of your shoes worn out more, you are likely an overpronator. If the shoes are laid on the floor and tilt outwards, as they get worn out on the entire outer edges, you supinate.
• Get someone to video record you at you foot level as you take three-five steps forward. Then play it back in slow motion.
The next step
•If you overpronate, you need shoes with a strong, firm raised support on the inner middle (medial) part of the sole.
• If you supinate, you need shoes with flexible medial parts, which will allow greater foot motion.
• Overpronators need to do extra stretching after a run, to normalize the muscles.
• Supinators should do extra stretching for the calves, hamstrings, quads and iliotibial band (a superficial thickening of tissue on the outside of the thigh, extending from the outside of the pelvis, over the hip and knee. The band is crucial for stabilizing the knee during running).
You may not know this
Did you know that most of us have one foot longer than the other? Measure each and check. It is important to buy shoes based on your longer foot.
Sometimes, one of our legs is, or seems, a bit longer than the other if the pelvis has twisted over time with your gait. Check two equally calibrated weighing machines and put one foot on each. You’ll see the differential weight each foot seems to be carrying. It would be advisable to consult a sports medicine doctor and get some corrective orthotics if necessary.
(Rahul S. Verghese is a management consultant and founder of runningandliving.com. Write to us at firstname.lastname@example.org)