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Human gait refers to locomotion achieved through the movement of human limbs. Human gait is defined as bipedal, biphasic forward propulsion of center of gravity of the human body, in which there are alternate sinuous movements of different segments of the body with least expenditure of energy. Different gait patterns are characterized by differences in limb movement patterns, overall velocity, forces, kinetic and potential energy cycles, and changes in the contact with the surface (ground, floor, etc.). Human gaits are the various ways in which a human can move, either naturally or as a result of specialized training.
Gaits can be roughly categorized into two groups: the natural gaits that nearly every human will use without special training, and the specialized gaits which people train to use under specific conditions and situations.
Another classification system applicable to humans groups gaits by whether or not the person is continuously in contact with the ground.
The specialized gaits include those trained for martial arts and entertainment, as well as additional gaits for regular motion that don't necessarily occur naturally. However, any gait that is not a natural gait is considered specialized.
The so–called natural gaits, in increasing order of speed, are the meander, walk, jog, run, and sprint. While other intermediate speed gaits may occur naturally to some people, these five basic gaits occur naturally across almost all cultures.
All natural gaits are designed to propel a person forward, but can also be adapted for lateral movement. As natural gaits all have the same purpose, they are mostly distinguished by when the leg muscles are used during the gait cycle.
The walk is a gait which keeps at least one foot in contact with the ground at all times. The walk is characterized by using leg muscles as the primary driving force, in contrast with the meander.
The walk is performed with the following steps:
Too much is unknown about how the human nervous system controls locomotion; many regions contribute, such as the frontal lobe, cerebellum, basal ganglia, brainstem, and spinal cord. For example, the pedunculopontine nucleus (PPN) is a nucleus of the brainstem that helps to control the planning and execution of gait. The PPN is connected extensively with other parts of the brain, including the spinal cord, cortex, and basal ganglia; these regions work together to plan, initiate, and maintain gait.
One variable in gait is foot strike – how the foot contacts the ground, specifically which part of the foot first contacts the ground.
In sprinting, gait typically features a forefoot strike, but the heel does not contact the ground.
Some researchers classify foot strike by the initial center of pressure; this is mostly applicable to shod running (running while wearing shoes). In this classification:
Foot strike varies to some degree between strides, and between individuals. It varies significantly and notably between walking and running, and between wearing shoes (shod) and not wearing shoes (barefoot).
Typically, barefoot walking features heel or midfoot strike, while barefoot running features midfoot or forefoot strike. Barefoot running rarely features heel strike because the impact can be painful, the human heel pad not absorbing much of the force of impact. By contrast, 75% of runners wearing modern running shoes heel strike; running shoes being characterized by a padded sole, stiff soles and arch support, and sloping down from a more padded heel to a less padded forefoot.
The cause of this change in gait in shoe running is unknown, but Liebermann noted that there is correlation between the foot-landing style and exposure to shoes. In some individuals, the gait pattern is largely unchanged – the leg position and foot position are identical in barefoot and shoe running – but the wedge shape of the padding moving the point of impact back from the forefoot to the midfoot. In other cases, it is conjectured that the padding of the heel softens the impact and resulting in runner modifying their gait to contact further back in the foot.
A 2012 study involving Harvard University runners found that those who "habitually rearfoot strike had approximately twice the rate of repetitive stress injuries than individuals who habitually forefoot strike". This was the first study that investigated the link between foot strike and injury rates. However, earlier studies have shown that smaller collision forces were generated when running forefoot strike compared to rear-foot strike. This may protect the ankle joints and lower limbs from some of the impact-related injuries experienced by rear-foot strikers.
There are gender differences in human gait patterns: females tend to walk with smaller step width and more pelvic movement. Gait analysis generally takes gender into consideration. Gender differences in human gait can be explored using a demonstration created by the Biomotion Laboratory at Queen's University, Kingston, Canada. BMLWalker