ABSTRACT
This study aimed to investigate load distribution and forearm muscle activity from strong to weak grip strength, using a cylindrical device (Grip Sensor). We invited 15 students and measured the pressure distribution and forearm muscle activity during grip tasks at 25%, 50%, 75%, and 100% maximum voluntary force (MVF). Pressure data from the Grip Sensor were assigned to seven anatomical regions; the sum of the data from the seven regions (Total force) and proportionate load distribution for each grip task were calculated. Electromyography recorded activity in the extensor carpi radialis longus (ECRL), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU) and flexor carpi ulnaris (FCU) muscles. Forearm muscle activity increased significantly with grip strength (p < 0.05). The load proportion corresponding to the thumb did not significantly change with increasing strength. On the other hand, the fingertip ratio significantly decreased, and the palm ratio significantly increased with increasing strength (p < 0.05). The Grip Sensor showed a shift in the load distribution in the hand from fingertips to palm as grip strength increased. This result indicates that more detailed evaluations of hand function may be possible.
