Table 2. Comparison of the results between the chronic low back pain (CLBP) group and the non-CLBP group.

Item	Factor	CLBP group	Non-CLBP group	p value
Human body composition	BMI (kg/m2)	23.2 ± 3.9	22.6 ± 4.7
	Skeletal muscle (kg)	25.2 ± 6.4	24.9 ± 5.9
	Body fat percentage (%)	28.3 ± 8.4	27.0 ± 7.6
	Extracellular water ratio (%)	0.4 ± 0.01	0.4 ± 0.01
Transverse abdominis muscle thickness (mm)	Static state	2.9 ± 0.6	2.9 ± 0.6
	End of inspiration	2.3 ± 0.5	2.3 ± 0.5
	End of expiration	3.7 ± 0.9	3.6 ± 0.6
	Transverse abdominis muscle contraction	5.0 ± 1.3	4.6 ± 0.9
	Double muscle contractiona	5.4 ± 1.3	6.3 ± 1.1	**

Data are presented as mean ± standard deviation; *p<0.05, **p<0.01.

^a Simultaneous contraction of the pelvic floor and transverse abdominis muscles.