Fig 2. Pressure pain threshold testing results in the high utilizer (n = 25) vs low utilizer (n = 9) groups.

Pressure was increasingly applied at a constant rate with a hand-held digital algometer 4 times at each site (masseter (A), trapezius (B), and ulna (C)). Subjects pushed a button when the pressure became painful, and the recordings were averaged. Average pressure pain thresholds were lower in the high utilizer group at all 3 sites, with a statistically significant difference at the ulna (p = 0.042).