Table 2.

Comparison of muscle thickness (mm) and echo intensity (0-255) among the age groups

	age group of 20’s	age group of 30’s	age group of 40’s	age group of 50’s	age group of 60’s
	(n = 23)	(n = 18)	(n = 22)	(n = 26)	(n = 23)
Significant difference compared with 20’s group (*p < 0.05, **p < 0.01) Significant difference compared with 30’s group (†p < 0.05, ‡p < 0.01) Significant difference compared with 40’s group (∫p < 0.05, §p < 0.01)
Muscle thickness
Rectus abdominis	9.59 ± 1.75	8.94 ± 1.86	8.20 ± 1.85	7.72 ± 2.13**	7.27 ± 1.39**†
External oblique	6.15 ± 1.45	5.77 ± 1.49	5.31 ± 1.40	4.39 ± 1.16**‡	4.35 ± 1.11**‡
Transversus abdominis	3.72 ± 0.49	3.92 ± 1.18	3.78 ± 1.13	3.28 ± 0.65	3.58 ± 0.82
Lumbar multifidus	26.25 ± 3.76	27.18 ± 4.45	26.65 ± 4.53	27.87 ± 4.66	26.85 ± 4.27
Echo intensity
Rectus abdominis	38.93 ± 28.58	60.52 ± 18.68*	73.13 ± 18.35**	82.24 ± 14.34**‡	87.61 ± 20.98**‡
External oblique	56.77 ± 17.17	73.50 ± 10.82**	81.74 ± 13.39**	85.18 ± 10.56**†	88.23 ± 13.49**‡
Transversus abdominis	19.42 ± 13.36	32.90 ± 12.84*	34.07 ± 15.69**‡	48.68 ± 13.12**‡§	46.00 ± 17.61**‡
Lumbar multifidus	30.22 ± 13.21	34.23 ± 14.02	41.06 ± 14.91*	49.52 ± 10.08**‡	51.36 ± 12.90**‡