6. Microelectronics for Muscle Fatigue Monitoring Through Surface EMG

Electromyogram (EMG), the recording of the electrical impulses of the muscles, is a rich source of information, which can facilitate such an insight into our muscles and especially their activation and fatigue level. Muscle fatigue has been shown to be one of the most important biofeedback parameters of EMG in rehabilitation, ergonomics and training, by using measured results from the body to change the way we behave, improve our performance and achieve better compliance to rehabilitation. This chapter addresses the challenge of reliably and efficiently estimating a muscle’s fatigue state through monitoring surface EMG signals, with the use of low power integrated circuits. CMOS technology facilitates localised real-time processing to achieve complete miniaturisation, resulting in an information driven system rather than conventionally data driven system. Thus, reducing requirements on data transmission, saving power and increasing the degree of freedom for the user. Several EMG properties progressively change during muscle fatigue and can be quantified in the time and frequency domains using different processing techniques, however this chapter focuses on the measurement of muscle fibre conduction velocity as an indicator of fatigue. A novel bit-stream cross-correlator design that greatly simplifies the sEMG signal without any loss of information is presented for the estimation of the EMG conduction velocity, which is associated with the physiological changes of the muscle during fatigue. The proposed approach is scalable, as several muscle fatigue monitoring SoCs can operate in parallel and periodically relay key information about the muscle, thus reducing data transmission costs and bandwidth requirements.