%0 Journal Article %A Cameron R. Taylor %A Seong Ho Yeon %A William H. Clark %A Ellen G. Clarrissimeaux %A Mary Kate O’Donnell %A Thomas J. Roberts %A Hugh M. Herr %T Untethered Muscle Tracking Using Magnetomicrometry %D 2022 %R 10.1101/2022.08.02.502527 %J bioRxiv %P 2022.08.02.502527 %X Muscle tissue drives nearly all movement in the animal kingdom, providing power, mobility, and dexterity. Technologies for measuring muscle tissue motion, such as sonomicrometry, fluoromicrometry, and ultrasound, have significantly advanced our understanding of biomechanics. Yet, the field lacks the ability to monitor muscle tissue motion for animal behavior outside the lab. Towards addressing this issue, we previously introduced magnetomicrometry, a method that uses magnetic beads to wirelessly monitor muscle tissue length changes, and we validated magnetomicrometry via tightly-controlled in situ testing. In this study we validate the accuracy of magnetomicrometry against fluoromicrometry during untethered running in an in vivo turkey model. We demonstrate real-time muscle tissue length tracking of the freely-moving turkeys executing various motor activities, including ramp ascent and descent, vertical ascent and descent, and free roaming movement. Given the demonstrated capacity of magnetomicrometry to track muscle movement in untethered animals, we feel that this technique will enable new scientific explorations and an improved understanding of muscle function.Competing Interest StatementCT, SY, and HH have filed patents on the magnetomicrometry concept entitled "Method for neuromechanical and neuroelectromagnetic mitigation of limb pathology" (patent WO2019074950A1) and on implementation strategies for magnetomicrometry entitled "Magnetomicrometric advances in robotic control" (US pending patent 63/104942). The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. %U https://www.biorxiv.org/content/biorxiv/early/2022/08/04/2022.08.02.502527.full.pdf