Table 4. Comparison of intraclass correlation coefficients for back extensor musculature between groups.

%HAT		Left ULES	Right ULES	Left LLES	Right LLES	Left BF	Right BF	Mean	p
100	Control	.80	.88	.94	.93	.94	.91	.90	.037*
	LBP	.74	.88	.85	.81	.72	.88	.81
110	Control	.81	.74	.92	.90	.95	.93	.88	.044*
	LBP	.60	.79	.75	.72	.83	.86	.76
120	Control	.88	.93	.97	.95	.98	.96	.95	.005*
	LBP	.57	.80	.73	.74	.88	.88	.77
130	Control	.85	.91	.96	.94	.98	.93	.93	.008*
	LBP	.37	.71	.63	.68	.86	.84	.68
140	Control	.89	.92	.96	.94	.98	.95	.94	.006*
	LBP	.46	.72	.57	.64	.89	.88	.69
150	Control	.89	.92	.97	.94	.98	.97	.95	.011*
	LBP	.03	.61	.33	.44	.88	.86	.53
160	Control	.87	.90	.90	.87	.98	.80	.89	.019*
	LBP	.21	.67	.67	.62	.66	.90	.62
170	Control	.84	.90	.95	.91	.98	.95	.92	.025*
	LBP	.45	.31	.67	.65	.92	.92	.65
MVIA	Control	.92	.96	.96	.93	.99	.96	.95	.021*
	LBP	.36	.52	.72	.72	.93	.94	.70
p		< .0001†	.002†	< .0001†	< .0001†	.001†	.043†

HAT: head, arms, trunk segment. LBP: Low back pain. ULES: Upper lumbar erector spinae. LLES: Lower lumbar erector spinae. BF: biceps femoris* p ≤ 0.05 between LBP and Controls Groups for each % HAT.†  p ≤ 0.05 between LBP and Controls Groups for the specific muscle group in that column.