VALD HumanTrak measures valid hip and knee joint angles with and without body armor

Introduction: Assessing kinematic information within military populations can assist in optimizing physical performance and identifying inefficient movement patterns patterns as part of a regular health screening. The HumanTrak is a portable markerless motion capture system capable of quantifying lower body kinematics within field-based settings. The literature to support HumanTrak validity is novel and has not been assessed in a military context. Valid data under specific military conditions are required to support the use of the HumanTrak device within a military setting in order to validate the findings in this unique population.

Material and Methods: The validity of the HumanTrak was examined in 17 individuals who completed lower body frontal and sagittal plane tasks at the hip and knee (Protocol Number: 52022787737978). Tasks were performed with and without body armor being worn. All tasks were assessed for peak angles and range of motion outputs from 3 repetitions in a laboratory. HumanTrak outputs were compared to a gold-standard methodology (marker-based motion capture). Standard error of measurement, intraclass correlations, Bland-Altman Plots, and Pearson Correlations of each system's lower body kinematic outputs were calculated.

Results: The results generally showed good validity between the systems' outputs for most movement tasks. Overall, low absolute measures of error for all tasks were observed, indicating that the HumanTrak can accurately measure lower body kinematics with minimal error. Besides hip flexion, minimal validity differences were seen between the body armor and no body armor conditions.

Conclusion: The HumanTrak's validity results suggest it provides a valid and accurate representation of lower body kinematics, making it useful for military and sports science applications. Practitioners can confidently use the HumanTrak to quantify lower body kinematics without requiring a sterile laboratory environment, like a gymnasium setting.