WHY LEG CROSSING - THE INFLUENCE OF COMMON POSTURES ON ABDOMINAL MUSCLE-ACTIVITY

Study Design. Abdominal muscle activity is recorded in the supine posi tion, unconstrained standing, and in the sitting position on an office chair with the use of backrest and armrests, with and without crossed legs. Objectives, To assess the role of oblique abdominal muscles in relation to the stability of lumbar spine and pelvis in commonly adopt ed unconstrained postures. Summary of Background Data. Cross-legged si tting is very common for men and women, No solid evidence exists for e ither a beneficial or a detrimental effect of this posture. No electro myographic study deals with the activity of abdominal muscles in this commonly adopted unconstrained posture. Methods. In healthy subjects, electromyographic activity of the rectus abdomini and external and int ernal oblique abdominals was recorded bilaterally during commonly adop ted unconstrained postures. Results. The activity of the internal obli que muscle was significantly higher in the sitting position than in th e supine position. For the external and internal oblique abdominals, t he activity was significantly higher in the standing position than in the sitting position. When sitting, the activity of the oblique abdomi nals is significantly lowered by crossing the legs in the preferred wa y (either upper legs crossed or ankle on knee). In contrast, the activ ity of the rectus abdominis is not significantly altered by leg crossi ng. Conclusions. From these remarkable findings, we conclude that leg crossing is physiologically valuable. It should be studied whether leg crossing can be implemented in the design of the workplace.