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Why Leg Crossing?: The Influence of Common Postures on Abdominal Muscle Activity

Snijders, Chris J., PhD*,∥; Slagter, Armande H.E., MSc*; van Strik, Roel, PhD; Vleeming, Andry, PhD; Stoeckart, Rob, PhD; Stam, Henk J.§

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Study Design Abdominal muscle activity is recorded in the supine position, 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 obdominal muscles in relation to the stability of lumbar spine and pelvis in commonly adopted unconstrained postures.

Summary of Background Data Cross-legged sitting is very common for men and women. No solid evidence exists for either a beneficial or detrimental effect of this posture. No electromyographic study deals with the activity of abdominal muscles in this commonly adopted unconstrained posture.

Methods In healthy subjects, electromyographic activity of the reclus abdomini and external and internal oblique abdominals was recoreded bilaterally during commonly adopted unconstrained postures.

Results The activity of the internal oblique muscle was significantly higher in the sitting position than in the supine position, For the external and internal oblique abdominals, the activity was significantly higher in the standing position than in the sitting position, When sitting, the activity of the oblique abdominals is significantly lowered by crossing the legs in the preffered way (either upper legs crossed or ankle on knee). In contrast, the activity of the rectus abdominis is not significantly altered by leg crossing.

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.

*Department of Biomedical Physics and Technology

Department of Anatomy

Department of Epidemiology and Biostatistics

Department of Rehabilitation, Faculty of Medicine and Allied Health Sciences, Erasmus University,Rotterdam,The Netherlands

§Faculty of Industrial Design Engineering, Delft University of Technology, Delft, The Netherlands.

© Lippincott-Raven Publishers.