Changes of motor control strategy of lumbar spine during complicated activities

Muscles are involved in complex and three dimensional activities. Timing and response to onset of external trigger need to perception and processing of data in central nervous system. The propose of this study is to determine reaction time, pre motor time and motor time with and without external load in healthy subjects. Twenty healthy subjects contributed in this study. Isoinertial dynamometer was used to assess complicated motions in sagital, frontal and transverse planes from full flexion, rotation and lateral flexion to right side to opposite direction inclusive full extension, rotation and lateral flexion to left side without and with 25 and 50% MVE. Reaction time, pre motor time, motor time, and maximum torque were also measured. Following combined motions, reaction time and pre motor time were increased by external load (25 and 50% MVE). Lateral flexion showed more changes than extension (P<0.001). By increasing load, particularly in extension; time and maximum torque were changed (P<0.001). Reaction time and pre motor time in combined motions are affected under extension and lateral flexion motions. Rotation has less effect on combined motions. Motions occur in sagital and frontal plane more than transverse plane.