Editing Gait analysis (section)

== Techniques ==
[[File:Two repetitions of a walking sequence of an individual recorded using a motion-capture system.gif|thumb|Walking sequences recorded by [[motion capture]]]]

Gait analysis involves measurement,<ref>U. Tasch, P. Moubarak, W. Tang, L. Zhu, R.M. Lovering, J. Roche, R. J. Bloch. (2008). An Instrument that Simultaneously Measures Spatiotemporal Gait Parameters and Ground Reaction Forces in Locomoting Rats, in ''Proceeding of 9th Biennial ASME conference on Engineering Systems Design & Analysis, ESDA ‘08.'' Haifa, Israel, pp. 45–49.</ref> where measurable parameters are introduced and analyzed, and interpretation, where conclusions about the subject (health, age, size, weight, speed, etc.) are drawn. The analysis is the measurement of the following:

=== Temporal / spatial ===

It consists of the calculation of speed, the length of the rhythm, pitch, and so on. These measurements are carried out through:
* Stopwatch and marks on the ground.
* Walking on a pressure mat.
* Range laser sensors scanning a plane a few centimeters above the floor.<ref>{{cite journal|last1=Piérard|first1=S.|last2=Azrour|first2=S.|last3=Phan-Ba|first3=R.|last4=Van Droogenbroeck|first4=M.|title=GAIMS: A reliable non-intrusive gait measuring system|journal=ERCIM News|date=October 2013|volume=95|pages=26–27|url=http://ercim-news.ercim.eu/en95/special/1359-gaims-a-reliable-non-intrusive-gait-measuring-system}}</ref><ref>{{cite web|title=The GAIMS project|url=http://www.montefiore.ulg.ac.be/gaims}}</ref>
* Inertial sensors and software to interpret 3D gyroscopes and 3D accelerometric data.

=== Kinematics ===
# [[Chronophotography]] is the most basic method for recording of movement. [[Strobe lighting]] at known frequency has been used in the past to aid in the analysis of gait on single photographic images.<ref>[[Étienne-Jules Marey]]</ref><ref>[[Muybridge|Eadweard Muybridge]]</ref>
# [[Cine film]] or 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 three dimensions rather than two dimensions only.
# Passive marker systems, using reflective markers (typically reflective balls), allows for accurate measurement of movements using multiple cameras (typically five to twelve cameras), simultaneously. The cameras utilize high-powered strobes (typically red, near infrared or infrared) with matching filters to record the reflection from the markers placed on the body. Markers are located at palpable anatomical landmarks. Based on the angle and time delay between the original and reflected signal, triangulation of the marker in space is possible. Software is used to create three dimensional trajectories from these markers that are subsequently given identification labels. A computer model is then used to compute joint angles from the relative marker positions of the labeled trajectories.<ref>{{cite journal |vauthors=Davis RB, Õunpuu S, Tyburski D, Gage JR| year = 1991 | title = A gait analysis data collection and reduction technique | journal = Human Movement Science | volume = 10 | issue = 5| pages = 575–587 | doi=10.1016/0167-9457(91)90046-z}}</ref> These are also used for [[motion capture]] in the motion picture industry.<ref>Robertson DGE, et al. (2004). ''Research Methods in Biomechanics''. Champaign IL:Human Kinetics Pubs.</ref>
# Active marker systems are similar to the passive marker system but use "active" markers. These markers are triggered by the incoming infra red signal and respond by sending out a corresponding signal of their own. This signal is then used to triangulate the location of the marker. The advantage of this system over the passive one is that individual markers work at predefined frequencies and therefore, have their own "identity". This means that no post-processing of marker locations is required, however, the systems tend to be less forgiving for out-of-view markers than the passive systems.<ref>{{Cite book|last1=Best|first1=Russell|last2=Begg|first2=Rezaul |year=2006|publication-date=30 March 2006|chapter=Overview of Movement Analysis and Gait Features| chapter-url=https://books.google.com/books?id=0yis6idPgy8C&pg=PA11|editor-last=Begg|editor-first=Rezaul|editor2-last=Palaniswami|editor2-first=Marimuthu|title=Computational Intelligence for Movement Sciences: Neural Networks and Other Emerging Techniques|publisher=Idea Group|pages =11–18|isbn=978-1-59140-836-9}}</ref>
# Inertial (cameraless) systems based on [[MEMS]] inertial sensors, biomechanical models, and sensor fusion algorithms. These full-body or partial body systems can be used indoors and outdoors regardless of lighting conditions.

=== Markerless gait capture ===
* Markerless gait capture systems utilize one or more color cameras or 2.5D{{explain|date=January 2022}} depth sensors (i.e. Kinect) to directly calculate the body joint positions from a sequence of images. The markerless system allows non-invasive human gait analysis in a natural environment without any marker attachment. Eliminating markers can expand the applicability of human gait measurement and analysis techniques, considerably reduce the preparation time, and enable efficient and accurate motion assessment in all kinds of applications. Currently, the main markerless system is the video-based motion capture with monocular camera or multiple camera studio.<ref>X. Zhang, M. Ding, G. Fan (2016) ''Video-based Human Walking Estimation by Using Joint Gait and Pose Manifolds'', IEEE Transactions on Circuits and Systems for Video Technology, 2016</ref> Nowadays, the depth sensor-based gait analysis for clinical applications becomes more and more popular. Since depth sensors can measure the depth information and provide a 2.5D depth image, they have effectively simplified the task of foreground/background subtraction and significantly reduced pose ambiguities in monocular human [[pose estimation]].<ref>{{cite web|url=https://sites.google.com/site/mengdingosu/home/research|title=Research – Meng Ding}}</ref>

===Pressure measurement===
Pressure measurement systems are an additional way to measure gait by providing insights into pressure distribution, contact area, center of force movement and symmetry between sides. These systems typically provide more than just pressure information; additional information available from these systems are [[force]], timing and spatial parameters. Different methods for assessing pressure are available, like a pressure measurement mat or walkway (longer in length to capture more foot strikes), as well as in-shoe pressure measurement systems (where sensors are placed inside the shoe).<ref>{{cite web |title=Gait Analysis with Pressure Measurement |url=https://www.tekscan.com/gait-analysis-systems |website=Tekscan |access-date=29 September 2017|date=9 June 2017 }}</ref><ref>{{cite journal |last1=Coda |first1=A. |last2=Carline |first2=T. |last3=Santos |first3=D. |year=2014 |title=Repeatability and reproducibility of the Tekscan HR-Walkway system in healthy children |doi=10.1016/j.foot.2014.02.004 |pmid=24703061 |volume=24 |issue=2 |journal=Foot (Edinb) |pages=49–55}}</ref><ref>{{Cite web|title=SCIENCE Insole3 Overview - Moticon|url=https://www.moticon.de/insole3-overview/|access-date=2020-12-18|language=en-US}}</ref> Many pressure measurement systems integrate with additional types of analysis systems, like motion capture, EMG or [[force platform|force plates]] to provide a comprehensive gait analysis.{{cn|date=December 2021}}

===Kinetics===
Is the study of the forces involved in the production of movements.

===Dynamic electromyography===
Is the study of patterns of muscle activity during gait.