Change in onset times of the abdominal muscles following functional task in lumbar spinal stenosis.

The purpose of this study was to investigate the difference in the onset times of the abdominal muscle following a rapid arm task in lumbar spinal stenosis (LSS). In total, 32 patients with LSS were recruited from W oriental hospital. Muscle activity onset of the internal oblique (IO) and external oblique (EO) muscles was measured by electromyography (EMG) activity with a rapid arm movement and during the performance of a walking task. The LSS group demonstrated a significantly later onset of the IO, EO, and rectus abdominal (RA) muscles than the normal group. The deltoid reaction time of the normal group demonstrated significantly earlier activations of IO and EO, while the deltoid reaction time of the LSS group demonstrated significantly delayed activations of IO and RA. The EMG measurements of the IO, EO, and RA muscles while standing and walking were reliable and they offer empirical information about the trunk muscle activation of LSS patients.