Figure 2
From: Altered neuromuscular control mechanisms of the trapezius muscle in fibromyalgia
Examples of a normalized muscle activity from a high-density EMG recording (caudal - cranial, channel 1 to 10, 5 mm's apart) from one healthy control (A) and one patient with fibromyalgia (C) performing a 1 kg weight of isometric shoulder elevation. The activity difference (B and D) in normalized activity between caudal and cranial regions segments (see A right) were used to calculate the power spectral median frequency.