sEMG activity during tests. Median sEMG level (%EMGmax) for clavicular and acromial fibers of dominant trapezius, middle deltoid, and biceps brachii during sympathetic activation, i.e., closing of epiglottis following deep inspiration (A), dominant arm movement (B), mental stress (C), and relaxation in the laboratory (D). Healthy controls (open circles) and fibromyalgia (FM) patients (filled circles) are represented by different symbols. Error bars indicate 95% CI of median.
Westgaard et al. BMC Musculoskeletal Disorders 2013 14:97 doi:10.1186/1471-2474-14-97