Table 4.

Percent change (means ± SDs) of lumbar multifidus muscle thickness at L4-5 and L5-S1 during three verbal instructions for all participants (n = 42), the asymptomatic group (n = 21) and the low back pain (LBP) group (n = 21).

Verbal instruction	#1	#2	#3	P
		L4-L5
All	3.85 ± 6.54	2.23 ± 3.50	5.24 ± 6.44	0.049*
Asymptomatic group	3.53 ± 6.61	2.57 ± 3.08	3.86 ± 5.45
LBP group	4.17 ± 6.60	1.89 ± 3.91	6.61 ± 7.17
		L5-S1
All	5.73 ± 4.87	4.90 ± 4.07	5.03 ± 4.92	0.643
Asymptomatic group	6.66 ± 4.78	5.72 ± 4.51	4.76 ± 4.74
LBP Group	4.80 ± 4.90	4.09 ± 3.50	5.31 ± 5.19

Verbal instruction #1: swell out the muscle underneath the transducer. Verbal instruction #2: Draw your belly button in towards your spinal column. Verbal Instruction #3: think about tilting your pelvis but without really doing it.

^*P < 0.05.