ABSTRACT
This section considers electromyography, or the study of the electrical activity of muscles as they generate tension, from the perspective of the sport and exercise biomechanist. For biomechanists to be able to analyse electromyograms (EMGs), i.e. the signal detected by electrodes from the muscle, they must understand the source of the signal; thus, the physiological nature of the signal is described. Important characteristics of the equipment (electrodes, amplifiers, filters, etc.) are explained and evaluated. Procedures used to record EMGs with a high signal-to-noise ratio, including skin preparation, electrode location and the reduction of the signal from adjacent muscles (cross-talk) are also discussed. Electromyograms are seldom left in their raw state once recorded, and this section details processing methods that are commonly used to obtain the amplitude of the signal. Normalisation procedures, to allow processed EMGs to be compared between different muscles and/or people, are also evaluated. Although the magnitude of EMGs is often analysed over time (i.e. time domain processing), the frequency content of the raw signal is also often of interest, for example in the analysis of muscle fatigue. This section concludes by summarising the methods available for such frequency domain analysis.
