Changes in SEMG during the Long Duration Cycling Exercise

Identification of muscle fatigue using surface electromyogram (SEMG) has always been both desirable and difficult for the engineering and medical community. Changes in SEMG are already established by authors when fatigue occurs as a result of short duration, supramaximal dynamic contraction. But most of the contractions that we have during a days work are not supramaximal and short duration, they are rather continuous and for longer duration and at a sub maximal level. So far reliability of SEMG has not been established for longer duration version of dynamic tasks. This study investigates into these kinds of dynamic contractions where subject performs cyclic dynamic contractions for a long duration. SEMG recordings were analyzed and results were compared with the blood samples and muscle biopsies to validate the results. These invasive techniques are used as current standard and reliable means of identifying muscle fatigue by many sports organizations such as Australian Institute of Sports (AIS), but these techniques are highly invasive, painful, time consuming and expensive. This paper reports a simple signal processing technique to identify muscle fatigue during cyclic activities of muscles such as VL and VM during cycling. Based on the experiments conducted with nine participants it was found that mechanism of fatigue is different in long duration sub-maximal cyclic exercise as compared to short duration, supramaximal dynamic cycling activity. Same was observed from this present study as the signal processing techniques described by authors were not successful to identify muscle fatigue in long duration sub-maximal cycling exercise