Gait analysis is the study of animal locomotion, including locomotion of humans. Gait analysis is commonly used to help athletes run more efficiently and to identify posture-related or movement-related problems in people with injuries.

The study encompasses quantification, i.e., introduction and analysis of measurable parameters of gaits, as well as interpretation, i.e., drawing various conclusions about the animal (health, age, size, weight, speed, etc.) from its gait.
 

With the development of photography, it became possible to capture image sequences which reveal details of human and animal locomotion that are not noticeable by watching the movement with the naked eye. Eadweard Muybridge and Étienne-Jules Marey were pioneers of this in the early 1900s. It was photography which first revealed the detailed sequence of the horse "gallop" gait, which is usually mis-represented in paintings made prior to this discovery, for example.

Although much early research was done using film cameras, the widespread application of gait analysis to humans with pathological conditions such as cerebral palsy, Parkinson's disease, and neuromuscular disorders, began in the 1970s with the availability of video camerasystems which could produce detailed studies of individual patients within realistic cost and time constraints. The development of treatment regimes, often involving orthopaedic surgery, based on gait analysis results, advanced significantly in the 1980s. Many leading orthopaedic hospitals worldwide now have gait labs which are routinely used in large numbers of cases, both to design treatment plans, and for follow-up monitoring.

The forefathers of this research are Murali Kadaba, HK Ramakrishnan, and Mary Wootten. Their main papers, dealing with Euler Angles, led to the development of a marker system. This marker system, referred to as the Helen Hayes Marker System is the predecessor of modern marker systems, such as the ones used in movies.
 

Gait analysis commonly involves the measurement of the movement of the body in space (kinematics) and the forces involved in producing these movements (kinetics).

Kinematics can be recorded using a variety of systems and methodologies:

1) Photography is the most basic method for the recording to movement and strobe lighting at known frequency has been used in the past to aid in the analysis of gait on single photographic images.

2) Video recordings using footage from single or multiple cameras can be used to measure joint angles and velocities. This method has been aided by the development of analysis software that greatly simplifies the analysis process and allows for analysis in 3 dimensions rather than 2 dimensions only.

3) Passive marker systems, using reflective markers (typically reflective balls), allow for very accurate measurement of movement using multiple cameras (typically up to 8 cameras simultaneously). The cameras send out infra red light signals and detect the reflection from the markers placed on the body. Based on the angle and time delay between the original and reflected signal triangulation of the marker in space is possible. These are typically used for motion capture in movies.