Table 4.

Normalized surface electromyography results as percentage (Psychophysiological measures)

	FM (n = 51)	Control (n = 31)	p-value
Trapezius, left
Mean (SD)	1.6 (1.7)	0.6 (0.5)	< 0.001
Median [Min, Max]	1.0 [0.2, 8.0]	0.4 [0.1, 2.0]
Trapezius, right
Mean (SD)	1.5 (1.2)	0.7 (0.5)	< 0.001
Median [Min, Max]	1.0 [0.2, 5.5]	0.7 [0.1, 2.1]
Erector spinae, left
Mean (SD)	4.0 (3.3)	2.2 (1.8)	0.002
Median [Min, Max]	3.0 [0.1, 12.8]	1.6 [0.4, 7.9]
Erector spinae, right
Mean (SD)	4.1 (4.2)	2.0 (1.2)	0.001
Median [Min, Max]	2.4 [0.5, 19.1]	1.7 [0.6, 5.1]
Biceps brachii, left
Mean (SD)	1.0 (0.8)	0.4 (0.3)	< 0.001
Median [Min, Max]	0.8 [0.2, 3.3]	0.4 [0.1, 1.4]
Biceps brachii, right
Mean (SD)	1.0 (0.8)	0.4 (0.4)	< 0.001
Median [Min, Max]	0.8 [0.1, 3.9]	0.4 [0.1, 2.0]

FM Fibromyalgia patients, SD standard deviation