Table 2. Contraction rates of the abdominal muscles in each position.

		CLBP	Healthy
Supine	TrA	1.89 ± 0.59	2.04 ± 0.78
	IO	1.23 ± 0.34	1.44 ± 0.34
	EO	1.01 ± 0.19	0.90 ± 0.18
Sitting	TrA	1.46 ± 0.29	1.69 ± 0.78
	IO	1.46 ± 0.38	1.50 ± 0.51
	EO	1.04 ± 0.26	0.97 ± 0.21
Standing	TrA*	1.27 ± 0.26	1.75 ± 0.57
	IO	1.39 ± 0.45	1.39 ± 0.32
	EO	0.96 ± 0.17	0.98 ± 0.29

change of thickness ratio=(contraction/resting). TrA= transversus abdominalis, IO= internal oblique, EO= external oblique (*p<0.05)