Sensor and Software for Monitoring Muscle Fatigue

We propose to develop an Electromyographic (EMG) system consisting of a high-performance EMG sensor, signal amplification and conditioning circuitry and a transmitter/receiver. The system will be attached to the skin, above the muscle(s) of interest, on soldiers performing training exercises and maneuvers. The specifications of the transmitter will be designed in collaboration with the Chem-Bio Defense Command, the Army Medical Command, the Human Engineering Directorate, and the Soldier System at Natick. The transmitted EMG signal will be analyzed to determine the rate of muscle fatigue by tracking the median frequency from the power density spectrum of the signal. This is a well-established technique for static muscle contraction. Because it is required to analyze dynamic muscle contraction, a new signal processing technique must be developed. We will use Time-Frequency analysis techniques for this purpose. The new technique will be tested on synthetic EMG signals and on real EMG signals detected from back muscles during lifting maneuvers. The new signal analysis technique will provide, for the first time, means to monitor the shift in the spectral characteristics of the EMG signal during short burst contractions which occur during daily functional activities.