Limb locomotion–speed distribution analysis as a new method for stance phase detection.

This study presents a new method for determining the stance phase during motion analysis. Utilizing data from high-speed video, this technique analyzes speed distribution and successfully establishes the stance phase in various species and conditions, showing a reliable correlation with kinetic stance phase detection.

Introduction to the Topic

• During motion analysis, determining the stance phase – the period when a foot is in contact with the ground – is crucial for understanding many parameters.
• In this study, researchers have developed a new kinematic method for identifying the stance phase based on high-speed video footage.

Detailed Methodology

• High-speed video data is used to calculate the speed distribution of a subject’s horizontal limb motion. The speed distribution refers to the range and frequency of different speeds observed during the motion cycle.
• The speed that occurs most often within the motion cycle is used to define the stance phase. Specifically, this ‘maximum occurrence speed’ serves as a threshold to determine the beginning and end of the stance phase.

Testing and Validation

• The reliability of this method was tested using seven horses, with the results compared to simultaneous stance phase measurement conducted using a ‘force plate’ integrated into a solid track.
• A force plate measures the ground reaction forces generated by a body standing on or moving across it, thus enabling direct stance phase determination.
• On average, the results from the new method differed by only 10.8 milliseconds, or 1.44% of the average stance phase duration, demonstrating a high degree of consistency and reliability.

Broader Application of the Method

• Further tests applied this method to a horse trotting on a treadmill and a human walking on concrete. The technique successfully determined the stance phase under both conditions, showing its flexibility and versatility.
• The method offers a safe and manageable way to analyze continuous kinematic data, particularly for determining the stance phase.
• It demonstrates potential for use in diverse species, various gaits (patterns of limb movement), and different ground conditions, expanding its field of application considerably.