The effects of force and joint angle on muscle conduction velocity estimation

Conduction velocity estimated from the surface myoelectric signal has been proposed as a potential index of fatigue for dynamic muscle contractions, in which joint angle and/or muscle force may be changing unpredictably. To be more useful as an index than power spectral parameters such as mean frequency, the conduction velocity estimate would have to be more resilient to changes in joint angle and/or muscle force. Results from this study using myoelectric signals collected from the biceps brachii, indicate that conduction velocity may indeed be more resilient to dynamic factors but also revealed that measurement techniques must be refined before reliable estimates can be obtained at joint angles in which extreme shortening of the muscle occurs.