As you walk or run, your foot should naturally rotate slightly inwards. This movement is called "pronation," and it is a completely natural and expected foot motion.

However, if your foot rotates so that you're walking or running almost entirely on the insides of your feet, your foot is rotating excessively. This excessive rotation is called "over-pronation" and can lead to discomfort or injury if not addressed.

While there's no definitive answer to the cause of over-pronation, we've found that those with low arches/flat feet or those with very flexible ankles are most prone to over-pronation.

Over-pronation does several things that we want to avoid:

1. It puts excess strain on the foot and ankle, which over time can lead to foot and ankle pain or injuries.
2. It can also put excess strain on the legs, knees, and hips, which can cause lower-body pain that it not isolated to the feet.
3. It puts an uneven amount of pressure on the inside of the foot, which can cause pain and soreness.
4. It causes your footwear to wear unevenly, where the insides of your shoes wear out faster than the outsides, which can be lead to discomfort and/or frequent shoe replacement.

The most important thing to do is to ensure that you have proper support for the arch and heel of your foot.

An arch support helps "guide" the foot into a natural pronation movement by cradling the heel of the foot and supporting the arch during movement such as walking or running. In most cases, this is sufficient to ensure that you don't over-pronate when you walk or run.

• Pronation is the natural "inwards rolling" movement of the foot and ankle when walking or running.
• Over-pronation is an excessive "inwards rolling" of the foot and ankle, causing you to walk or run heavily on the insides of your feet.
• Supination (or under-pronation) is the "outwards rolling" of the foot and ankle, causing you to walk or run heavily on the outsides of your feet.