Trunk muscle activity during walking in persons with multiple sclerosis: the influence of body weight support.

Background: Although the trunk is important for maintaining balance during walking only very limited information about the trunk muscle activity during walking with body weight support (BWS) is reported in literature.

Objective: The aim of this study was to measure the effect of BWS on the trunk muscle activity during treadmill walking.

Methods: 14 persons with multiple sclerosis and 14 healthy persons walked on a treadmill with 0%, 10%, 20%, 30%, 50% and 70% BWS. Bilateral EMG measurements (surface electrodes) on the m. rectus abdominis, m. obliquus externus, m. erector spinae and m. multifidus were performed. The maximal muscle activation was presented as a percentage of a performance related reference contraction. A repeated measures ANOVA with simple contrasts was applied (SPSS20).

Results: In general when comparing walking with BWS with walking with 0% BWS there is an increase in m. obliquus externus activity and a decrease in back muscle activity. With increasing percentages of BWS an increase in activity of the abdominal muscles and a decrease in back muscle activity was found, with most changes in high percentages BWS.

Conclusion: Based on the results, it is recommended to decrease the percentage BWS as fast as possible beneath 30% BWS.