Pronation
In anatomy, pronation is a rotational movement of the forearm (at the radioulnar joint) or foot (at the subtalar and talocalcaneonavicular joints). Pronation of the foot refers to how the body distributes weight as it cycles through the gait. During the gait cycle the foot can pronate in many different ways based on rearfoot and forefoot function. Types of pronation include neutral pronation, underpronation (supination), and overpronation.
- Neutral pronation
An individual who neutrally pronates initially strikes the ground on the lateral side of the heel. As the individual transfers weight from the heel to the metatarsus, the foot will roll in a medial direction, such that the weight is distributed evenly across the metatarsus. In this stage of the gait, the knee will generally, but not always, track directly over the hallux.
This rolling inwards motion as the foot progresses from heel to toe is the way that the body naturally absorbs shock. Neutral pronation is the most ideal, efficient type of gait when using a heel strike gait; in a forefoot strike, the body absorbs shock instead via flexation of the foot.
- Overpronation
As with a neutral pronator, an individual who overpronates initially strikes the ground on the lateral side of the heel. As the individual transfers weight from the heel to the metatarsus, however, the foot will roll too far in a medial direction, such that the weight is distributed unevenly across the metatarsus, with excessive weight borne on the hallux. In this stage of the gait, the knee will generally, but not always, track inwards.
An overpronator does not absorb shock efficiently. Imagine someone jumping onto a diving board, but the board is so flimsy that when it is struck, it bends and allows the person to plunge straight down into the water instead of back into the air. Similarly, an overpronator's arches will collapse, or the ankles will roll inwards (or a combination of the two) as they cycle through the gait. An individual whose bone structure involves external rotation at the hip, knee, or ankle will be more likely to overpronate than one whose bone structure has internal rotation or central alignment. An individual who overpronates tends to wear down their running shoes on the medial (inside) side of the shoe towards the toe area.
When choosing a running or walking shoe, a person with overpronation can choose shoes that have good inside support—usually by strong material at the inside sole and arch of the shoe. It is usually visible. The inside support area is marked by strong greyish material to support the weight when a person lands on the outside foot and then roll onto the inside foot.
- Underpronation (supination)
An individual who underpronates also initially strikes the ground on the lateral side of the heel. As the individual transfers weight from the heel to the metatarsus, the foot will not roll far enough in a medial direction. The weight is distributed unevenly across the metatarsus, with excessive weight borne on the fifth metatarsal, towards the lateral side of the foot. In this stage of the gait, the knee will generally, but not always, track laterally of the hallux.
Like an overpronator, an underpronator does not absorb shock efficiently - but for the opposite reason. The underpronated foot is like a diving board that, instead of failing to spring someone in the air because it is too flimsy, it fails to do so because it is too rigid. There is virtually no give. An underpronator's arches or ankles don't experience much motion as they cycle through the gait. An individual whose bone structure involves internal rotation at the hip, knee, or ankle will be more likely to underpronate than one whose bone structure has external rotation or central alignment. Usually - but not always - those who are bow-legged tend to underpronate. An individual who underpronates tends to wear down their running shoes on the lateral (outside) side of the shoe towards the rear of the shoe in the heel area.
Read more about this topic: Foot Type