A comparison of the timing of muscle activity during sitting down compared to standing up.

BACKGROUND AND PURPOSE This study was designed to investigate the temporal pattern of the activation and de-activation of muscles during sitting down to a seated position. The aim was to determine if reproducible patterns existed in the timing of muscle activation and deactivation, in normal subjects, and to compare that produced for sitting down with the pattern produced for standing up. METHOD The 10 subjects used for the experiment were a convenience sample consisting of healthy male volunteers aged 19-32 years. The design was that of a descriptive study. Subjects were instructed to stand up and sit back down to a seated position. During this activity kinematic (movement) and electromyographic (EMG) data were collected. A pattern of timing for the activity of different muscles or groups was produced and this was compared with the movement occurring. RESULTS The study found a consistent pattern of EMG activity during sitting down from a standing position. This pattern was documented and the pattern was compared with that produced during standing up. CONCLUSIONS The results demonstrated that a consistent pattern of muscle activation and de-activation was produced in this group of subjects during sitting down. The pattern of muscle activation and de-activation for sitting down was documented. When comparing the pattern produced during sitting down with that produced during standing up it is apparent that some of the muscles were active during both movement patterns at the same relative point in the pattern.