Abstract
[Purpose] To find a clinical method for using Straight Leg Raising (SLR) as an approach to the trunk muscle, we investigated how the leg and the trunk muscle activity were changed by the setting of the contralateral leg in SLR. [Subjects] The subjects were 21 healthy men (average age: 20.6±3.7 years old). [Methods] The SLR task was performed under three conditions: Push, Do not push, and Normal. We defined Push as SLR which is emphatically performed by pushing the supporting surface in a perpendicular direction with the contralateral leg. We defined Do not push as SLR which is performed without pushing the supporting surface. We defined Normal as SLR which is performed without a special condition. The contralateral leg was kept in a straight leg position. Surface electrodes were used to bilaterally measure the electromyographic activity of the erector spinae (lumbar part), rectus abdominis, medial hamstrings and rectus femoris (eight muscles in total). [Results] In Push, the numerical value of %MVC of the right and left erector spinae was significantly larger than that of the other two conditions. In Do not push, the numerical value of %MVC of the right and left rectus abdominis was significantly larger than that of the other two conditions. [Conclusion] Even if the movement of the spine is limited, the results suggest that it is possible to induce trunk muscle activity in a variety of clinical settings using the two conditions of Push and Do not push.
