Mechanomyography Spasticity Assessment of Flexor and Extensor Wrist Muscles for the Classification of Boccia Athletes in Para Sports: A Pilot Study

Abstract

The Paralympic boccia is a sport played by athletes with spasticity and severe impairment in the four limbs. Three (BC1, BC2, and BC3) of the four classes in boccia allow People with Cerebral Palsy (CP) to participate. The ranking is performed manually through the American Spasticity Scale. Like all qualitative scales, however, this evokes controversy among the evaluation board members who apply it, altering the classification of the athletes. A helpful option would be the use of mechanomyography (MMG), a method of acquiring muscle vibrations quantitatively based on accelerometers. Thus, the objective of this article was to conduct a pilot study analyzing the differences in the MMG signals of flexors and extensors muscles between two groups: 6 boccia athletes with spasticity and 6 non-impaired. Volunteers remained seated on the wheelchair, with their elbow bent close to 90°. They were verbally stimulated to perform the manual grip by pressing the evaluator’s hand while the MMG signals were recorded and stored. The mean MMG_RMS descriptor was calculated for each signal. The experimental tests indicated differences between the two groups. For the spasticity group: 0.4058 and 0.4258 mV for the left flexor and extensor wrist muscles, respectively; 0.4215 and 0.4529 mV for the right flexor and extensor wrist muscles, respectively. For the non-impaired group, the MMG_RMS was 0.3694 and 0.3945 mV for the left flexor and extensor wrist muscles, respectively; 0.35033 and 0.3728 mV for the right flexor and extensor wrist muscles, respectively. Thus, these results indicate greater spasticity for the spastic group and so, volunteers classification in lower levels.