Effects of muscle fatigue on the usability of a myoelectric human-computer interface

Electromyography-based human-computer interface development is an active field of research. However, knowledge on the effects of muscle fatigue for specific devices is limited. We have developed a novel myoelectric human-computer interface in which subjects continuously navigate a cursor to targets by manipulating a single surface electromyography (sEMG) signal. Two-dimensional control is achieved through simultaneous adjustments of power in two frequency bands through a series of dynamic low-level muscle contractions. Here, we investigate the potential effects of muscle fatigue during the use of our interface. In the first session, eight subjects completed 300 cursor-to-target trials without breaks; four using a wrist muscle and four using a head muscle. The wrist subjects returned for a second session in which a static fatiguing exercise took place at regular intervals in-between cursor-to-target trials. In the first session we observed no declines in performance as a function of use, even after the long period of use. In the second session, we observed clear changes in cursor trajectories, paired with a target-specific decrease in hit rates.     

Detecting motorcycle rider local physical fatigue and discomfort using surface electromyography and seat interface pressure

Whilst motorcycling is an activity of pleasure in most parts of the world, in India it is a regular mode of commuting. Incidence of fatigue is substantially higher among motorcycle riders than drivers of other modes of transport. The objective of this study was to detect physical fatigue due to motorcycle riding for an hour using surface electromyography (sEMG) and seat interface pressure. Twenty healthy male participants performed 60 min of motorcycle riding in a low traffic density environment. Muscle activity was recorded bilaterally from extensor carpi radialis (ECR), biceps brachii (BB), trapezius medial (TM), sternocleldomastoid (S) latissimus dorsi (LD) and erector spinae (ES) muscle groups. Interface seat pressure distribution was monitored using a pressure mapping system. Results showed that participants have significant (p < 0.05) physical fatigue in TM, LD and ES muscle groups during 60 min of motorcycle riding. Seat pressure distribution was found to be non-uniform during the course of motorcycling. Results suggest that the impact on local physical fatigue and seat discomfort are probably due to static seating demand and prolonged sitting posture balance required to ride the motorcycle for an hour.