Vanderweeën, L., Oostendorp, R. A. B., Vaes, P., & Duquet, W. (1996). Pressure algometry in manual therapy. Manual Therapy, 1(5), 258–265. https://doi.org/10.1054/math.1996.0276
The pressure pain threshold (PPT), i.e. the least stimulus intensity at which a subject perceives pain, was studied in 30 patients with chronic unilateral pain in the shoulder and arm region. Fourteen trigger points were investigated on both sides of the body using pressure algometry. Eight paravertebral points and six points in the shoulder and arm region were evaluated. Each location was examined twice. The patients were tested by one examiner.
Ylinen, J. (2007). Pressure algometry. Australian Journal of Physiotherapy, 53(3), 207. https://doi.org/10.1016/S0004-9514(07)70032-6
Pressure pain threshold (PPT) is defined as the minimal amount of pressure that produces pain. A simple handheld pressure algometer (PA) with a spring is commonly used, although more sophisticated electrical devices with a strain or pneumatic pressure gauge have been developed. They hold the peak force or pressure (kp (kilopond) = 10 N, Newton = 100 kPa (kilopascal)) until tared, and some may also be connected to a computer and thus have continuous output. PPT measured with a probe 1.6 mm in diameter or larger reflects the tenderness of deep tissues as anesthesia of skin only affects the results of smaller probes (Takahashi et al 2005). The most commonly used surface area of probes is 0.5 or 1 cm2. Rolke et al (2005) compared hand-held spring and electronic PAs and found no significant difference for clinical purposes. The PA is placed perpendicular to the tissue surface and pressure applied steadily at a constant rate. Reported pressure application rates have ranged from 0.05 to 20 N/s (Jensen et al 1986). Higher PPT scores were recorded at higher application rates. Ideally compression should be performed slowly enough to allow the subject time to react when pain is felt. When the subject reports feeling pain the action of pressure is stopped, or to avoid delay by the tester, by pressing a switch on an electronic PA.