Table 3.

Changes in muscle activity before and after six weeks of isometric exercise (M±SD, mV)

Muscle	Item	LBP Control		LBP Mat exercise		LBP I-Zer exercise
		Pre	Post	Pre	Post	Pre	Post
Longissimus thoracic (LT)	RMS	250.00±2.78	252.13±0.92	253.40±3.11	262.15±4.43*	242.45±4.55	274.70±8.38*
Longissimus thoracic (LT)	MDF	33.40±2.91	32.30±8.21	34.90±1.97	44.10±1.77*	34.30±1.71	45.80±2.28*
Longissimus thoracic (LT)	MNF	45.60±2.06	47.21±6.06	44.05±1.90	54.90±1.55	44.60±1.81	57.50±2.60*
Iliocostalis lumborum (IL)	RMS	260.40±1.95	262.14±2.29	259.85±2.79	272.00±3.30*	245.55±5.41	275.80±5.78*
Iliocostalis lumborum (IL)	MDF	38.80±4.96	39.10±2.93	38.65±1.66	47.10±1.86*	38.40±1.75	48.80±2.46*
Iliocostalis lumborum (IL)	MNF	48.80±1.93	47.62±2.23	45.80±1.85	51.40±1.59	46.6±1.78	61.35±3.09*
Multifidus (MF)	RMS	239.5±5.87	240.5±3.12	236.00±5.69	250.25±6.10*	236.35±5.83	256.95±5.91*
Multifidus (MF)	MDF	28.40±3.89	27.30±2.91	28.7±4.75	32.55±5.69	28.5±3.81	36.80±3.83*
Multifidus (MF)	MNF	37.80±3.76	38.79±1.06	38.3±3.01	42.65±2.77	38.9±2.07	48.15±2.99*
Rectus abdominis (RA)	RMS	255.00±2.78	257.00±1.42	253.40±3.11	272.15±4.43*	242.45±4.55	265.50±5.01*
Rectus Abdominis (RA)	MDF	32.40±2.91	31.64±2.21	32.75±2.76	35.75±2.91	33.60±3.57	43.90±3.87*
Rectus Abdominis (RA)	MNF	41.60±2.06	42.56±3.07	40.10±3.72	45.75±3.71	41.15±3.86	52.90±5.24*

LBP, low back pain patients; RMS, root mean square; MDF, median frequency; MNF, mean frequency.

^*P<0.05.