Total Forearm Muscle Activities in Various Hand Postures

This study examined total forearm muscle activities in five different hand postures of pinching with two fingers (2P), three fingers (3P), four fingers (4P), five fingers (5P), and power grip (5G). Male students participated in the experiment. EMG signals were recorded by using nine dual surface electrodes to record the activities of forearm muscles of flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), extensor carpi radialis (ECR), extensor carpi ulnaris (ECU), flexor digitorum superficialis (FDS), flexor digitorum profundus (FDP), extensor digitorum (ED), flexor pollicis longus (FPL), and extensor pollicis longus (EPL). The nine muscles were combined to estimate total muscle activities by the summation method of the EMG index. Analysis of variance showed that the total muscle activities were significant for the hand postures. The muscle activities for 2P and 3P hand postures were about 20 % higher than those for the 5P and 5G postures. Overall, the summation value of % MVC decreased as the number of fingers used increased.