Author(s): WOO, S., OH, D., Institution: DONG SEOUL UNIVERSITY, Country: KOREA, SOUTH, Abstract-ID: 175

INTRODUCTION:
Objective quantification of muscle force is fundamental in sports biomechanics and motor control research. While limb muscles have been extensively studied, monitoring methods for fine motor muscles remain limited. Orofacial muscles contribute to precision motor control influencing movement accuracy and coordination. Motor control theory posits that the nervous system modulates force generation in all muscle groups, including small orofacial muscles, to achieve precise motor tasks [1]. Neuromuscular activity of the craniomandibular system can affect postural stability and force production, suggesting interaction with whole body motor control relevant to sport and performance [2]. However, real time assessment tools are scarce. Electrical impedance sensing may provide a non invasive approach to capture muscle related mechanical changes. The purpose of this study was to examine whether electrical impedance phase can serve as a marker of force production and neuromuscular activation during repetitive orofacial tasks.
METHODS:
Ten healthy adults (age: 26 plus or minus 6.5 years) performed repetitive tongue press tasks at 30 percent and 60 percent of maximal voluntary contraction. Electrical impedance phase (IPA, degrees) was measured using a custom palatal sensor array and synchronized with tongue pressure (IOPI, kPa) and surface electromyography (sEMG, uV). Each task was repeated five times. Friedman tests with Bonferroni correction compared force conditions. Pearson correlation analyses evaluated associations between impedance phase, tongue pressure and sEMG.
RESULTS:
Significant differences were observed for impedance phase, tongue pressure and sEMG across force levels (p less than 0.001). Impedance phase correlated with tongue pressure (r equals 0.75 to 0.90) and sEMG (r equals 0.70 to 0.88). Higher force levels were associated with larger impedance phase shifts.
CONCLUSION:
Electrical impedance phase reflects force production and neuromuscular activation during fine motor tasks. These findings extend sports biomechanics principles to orofacial musculature and suggest that impedance based monitoring may be useful for performance assessment in tasks requiring precise motor control. This approach may support development of sensor based assessment and training technologies for precision demanding sports and rehabilitation.

References
[1] Shiffman CA, et al. Electrical impedance of muscle during isometric contraction: relation to force production and physiological changes. Med Biol Eng Comput. 2003;41:572-577.
[2] Ngo C, et al. A wearable multi frequency device to measure muscle electrical impedance and EMG for robust muscle contraction assessment. Sensors. 2022;22(5):1941.