Concerning the pectoralis major in active reaching exercise

This study was designed to address an active reaching exercise on the purpose of determining the individual and interaction effects of reaching directions, assistance conditions and the muscles. The activity of the muscles, the Serratus Anterior and Pectoralis Major, in 20 healthy male subjects was recorded in parallel by surface electrode of electromyography. Four conditions of reaching, upward reaching in shoulder flexion 90(0) and sideward reaching in shoulder abduction 90(0) with and without arm support were tested. The results showed a significant decrease in the muscle activity in the sideward reaching when compared with the upward addition to with arm support when compared with without arm support. The Pectoralis Major was significantly less activated than the Serratus Anterior. There was a significant decrease in the Pectoralis Major and Serratus Anterior activation during sideward reaching when compared with the upward. Furthermore, Pectoralis Major and Serratus Anterior muscles during reaching with arm support were less activated than without the support. The interaction between reaching directions, assistance conditions and muscles revealed that the least activation for Pectoralis Major muscle was the sideward reaching with arm support whilst for Serratus Anterior was the sideward reaching with and without arm support. It is suggested that in clinical application, particularly in the spastic Pectoralis Major muscle patients, an active reaching exercise should be first done in the sideward direction with support.