Table 2. Average EMG (µV) for each muscle at each percentage of HAT (head, arms, trunk segment). The asterisks signify significant differences between 140 and 160 % of HAT values for the muscle in that row.

%HAT		100		120		140		160
		Mean	SD	Mean	SD	Mean	SD	Mean	SD
Left ULES	Con	24.60	15.88	33.80	21.77	32.9	66.51	159.3*	143.41
	LBP	10.79	19.95	6.21	67.23	78.53	56.82	152.3*	183.71
Right ULES	Con	31.10	35.24	45.40	41.94	30.2	46.68	172.9*	142.94
	LBP	14.24	30.45	35.46	51.25	84.48	30.76	217.4*	331.06
Left LLES	Con	14.20	15.25	23.00	17.54	15.84	37.93	74.3*	50.91
	LBP	3.46	16.67	15.71	39.95	11.10	32.42	29.80	49.64
Right LLES	Con	12.50	17.43	22.20	18.20	13.5	47.31	93.5*	94.20
	LBP	2.01	21.03	18.48	28.76	50.31	68.26	53.51	108.52
Left biceps femoris	Con	7.00	15.18	19.13	27.35	0.12	40.50	119.0*	185.11
	LBP	18.71	29.79	58.09	109.67	124.09	139.24	125.27	354.92
Right biceps femoris	Con	19.60	24.74	16.80	36.05	23.10	45.06	129.7*	186.95
	LBP	13.73	28.33	65.76	63.05	183.51	359.86	53.17	144.73

Con: Control. LBP: Low back pain. ULES: Upper lumbar erector spinae. LLES: Lower lumbar erector spinae