Magnitude of muscle activity of the lumbar multifidus using the Core-Noodle device with varied upper extremity postures.

Background: Lumbar Multifidus (LM) exercise is a treatment in patients with low back pain. We designed a new exercise using device ``Core-Noodle'' (Copyright has been observed in Japan).

Objective: The purpose of this study was to record the electromyographic (EMG) activity of the lumbar multifidus during a novel exercise.

Methods: Twenty-one healthy young volunteers performed the LM exercise using Core-Noodle in three conditions: no-weight (NW), 1 kg weight (1W), 2 kg-weight (2W). This exercise was performed in supine with left shoulder abduct 90 degrees and right shoulder flexed 90 degrees. EMG activity was recorded from surface electrodes on the LM and the thoracic part of the iliocostalis lumborum (ICLT), and normalized to values derived from maximal isometric trials (%MVIC). In addition, the ratio of the LM to ICLT (L/G ratio) was calculated to compare selectivity of LM activity. One-way ANOVA and Bonferroni method were used to draw comparisons among the three conditions.

Results: Muscle activation of LM was gradually increased in proportion to the loading dose. L/G ratio increased by weight loading significantly, but slightly decreased at 2W.

Conclusions: The results suggest that characteristic EMG patterns of LM ``selective contraction'' and ``adjustment of load'' are obtained concurrently.