Editing Gait analysis (section)

==Process and equipment==
[[File:Gait laboratory.jpg|thumb|Gait analysis laboratory equipped with infrared cameras and floor mounted [[force platform]]s]]
A typical gait analysis laboratory has several cameras (video or infrared) placed around a walkway or a treadmill, which are linked to a computer. The patient has markers located at various points of reference of the body (e.g., iliac spines of the pelvis, ankle malleolus, and the condyles of the knee), or groups of markers applied to half of the body segments. The patient walks down the catwalk or the treadmill and the computer calculates the trajectory of each marker in three dimensions. A model is applied to calculate the movement of the underlying bones. This gives a complete breakdown of the movement of each joint. One common method is to use [[Helen Hayes Hospital]] marker set,<ref>{{cite journal|last1=Kadaba|first1=M. P.|last2=Ramakrishnan|first2=H. K.|last3=Wootten|first3=M. E.|s2cid=17094196|title=Measurement of lower extremity kinematics during level walking|journal=Journal of Orthopaedic Research|date=May 1990|volume=8|issue=3|pages=383–392|doi=10.1002/jor.1100080310|pmid=2324857|doi-access=free}}</ref> in which a total of 15 markers are attached on the lower body. The 15 marker motions are analyzed analytically, and it provides angular motion of each joint.{{cn|date=December 2021}}

To calculate the [[kinetics (physics)|kinetics]] of gait patterns, most labs have floor-mounted load transducers, also known as force platforms, which measure the ground reaction forces and moments, including the magnitude, direction and location (called the center of pressure). The spatial distribution of forces can be measured with [[pedobarography]] equipment. Adding this to the known dynamics of each body segment enables the solution of equations based on the [[Newton–Euler equations]] of motion permitting computations of the net forces and the net moments of force about each joint at every stage of the gait cycle. The computational method for this is known as inverse dynamics.{{cn|date=December 2021}}

This use of kinetics, however, does not result in information for individual muscles but muscle groups, such as the extensor or flexors of the limb. To detect the activity and contribution of individual muscles to movement, it is necessary to investigate the electrical activity of muscles. Many labs also use surface electrodes attached to the skin to detect the electrical activity or electromyogram (EMG) of muscles. In this way it is possible to investigate the activation times of muscles and, to some degree, the magnitude of their activation—thereby assessing their contribution to gait. Deviations from normal kinematic, kinetic or EMG patterns are used to diagnose specific pathologies, predict the outcome of treatments, or determine the effectiveness of training programs{{cn|date=December 2021}}