# Correlation study: electrical impedance-based approximation of knee joint angle and extensor strength during concentric knee extension

## TL;DR

This study explores using electrical impedance to estimate knee joint angle and muscle strength, offering a portable alternative to traditional methods.

## Contribution

The novel use of electrical impedance tomography for real-time estimation of knee joint angle and extensor strength is introduced.

## Key findings

- EIT signals correlate with knee joint angle during concentric extension.
- EIT data reflect extensor strength linked to torque levels.
- EIT shows potential for portable, real-time muscle function monitoring.

## Abstract

Musculoskeletal disorders often lead to pain, limited mobility, and reduced quality of life. Monitoring muscle function is crucial for understanding and treating these conditions, yet current methods like dynamometry are impractical for daily use. Consequently, there is a clear need for practical, clinically applicable solutions to estimate muscle function. This work used electrical impedance tomography (EIT) measurements as a non-invasive alternative. EIT data were recorded from the thigh during concentric knee extension at predefined torque levels, simultaneously measured with a dynamometer. A data-driven model was applied to analyze conductivity changes linked to muscle activation. Results indicate that EIT signals reflect knee joint angle and extensor strength, highlighting its potential for portable, real-time monitoring in clinical settings.