Purpose : To offer coupled motion caused by sidebending in the extension postures in lumbar spine in the football, baseball players and general students. Method : Coupled motion were analysed by three dimensional motion analyser in the sitting position during lateral bending. Result : Regardless of the direction of sidebending at L1-L3, L5-S2 in the extension posture of the lumbar spine, the direction of coupled motion in the baseball and football players were opposite to the direction of sidebending but the direction of coupled motion was same at L3-L5. while, the direction of sidebending at L1-L3, L3-L5 in the extension posture of the lumbar spine, the direction of coupled motion in the general students were same to the direction of sidebending but, the direction of coupled motion was opposite direction at L5-S2. Conclusion : we found a difference of coupled motion between athletes and non-athletes.