抄録
Purpose: The purpose of this study was to clarify the effective motor control to trunk muscles by quantitatively analyze the lumbar movement during active leg raise under different strategies for lumbar stabilization in healthy subjects. Methods: Twenty-three healthy male (mean age 22.8 ± 5.4 years) subjects participated in this study. Firstly, subjects were instructed to perform three different types of contraction of trunk muscles in the supine position as follows: 1) control condition: involuntary, 2) hollowing condition: draw-in the abdominal wall at 20％ maximum voluntary contraction (MVC) using a modified Richardson’s method, 3) bracing condition: brace the abdominal wall at 20％ MVC without change of abdominal girth using a modified McGill’s method. Secondly, the amount, timing and sharpness of lumbar movement during the leg raise from crook lying position under each conditions were recorded with a custom-made back pressure recording device placed beneath the back and a foot switch placed beneath the heel. Data analysis was performed using a bio-signal analyzing software (BIMUTAS version 2.0E, Kissei Comtec, Japan). Results: 20 subjects (87% ) demonstrated the lumbar moves in the direction of the lordosis preceding leg raise. The amount and sharpness of this movement in bracing exercise were significantly lower than the hollowing and control exercise conditions (p < 0.05)． Conclusions: This study suggested that motor control in trunk muscles during bracing condition was more effective for lumbar stability compared with hollowing and control conditions in healthy subjects.
