Assessment of pain processing is essential to understand underlying mechanisms, personalize treatments, and improve rehabilitation. Pain processing mechanisms, including pressure pain thresholds (PPT), temporal summation, and conditioned pain modulation (CPM), play a crucial role in understanding pain sensitivity and modulation in both clinical and research settings. Reliable assessment of these measures is essential for accurately evaluating pain responses and guiding treatment strategies. However, the consistency of these measurements in asymptomatic individuals remains a critical factor in ensuring their validity for broader applications.

To assess the reliability, reliability, standard error of measurement (SEM), and minimal detectable change (MDC) of Pressure pain thresholds (PPT), temporal summation, and Conditioned pain modulation (CPM) in asymptomatic individuals.

This is a cross-sectional study. This study was approved by Ethics Research Committee. Two assessment sessions were conducted for assessment of test-retest reliability with an average interval of 3.80 ± 1.69 days. PPTs were assessed with a digital algometer (AlgoMed®, Hörby, Sweden) at four anatomical points: deltoid, acromion, trapezius, and anterior tibialis. The order of evaluation was randomized. Each point was measured three times, and the average was calculated. Temporal summation testing was also conducted on the deltoid and anterior tibialis, where the previously determined PPT pressure was applied 10 consecutive times. Pain intensity was recorded using the 11-point Numeric Pain Rating Scale before and after the last stimuli. CPM was evaluated using the cold pressor test, with PPT serving as the test stimulus. The participant’s hand immersed in cold water (8°C) for two minutes and the PPT was measured on the deltoid during and after immersion. The reliability was assessed with Intraclass Correlation Coefficient (ICC 3.3) and measurement error with SEM and MDC95. ICC(3,3) with values interpreted as follows: greater than 0.90 as excellent, 0.75 to 0.90 as good, 0.50 to 0.75 as moderate, less than 0.50 as poor reliability.

Ten asymptomatic individuals (7 women, mean age of 25 ± 4.12 years) participated in the study. The PPT of trapezius (ICC = 0.88; SEM = 0.13; MDC95 = 0.86), and anterior tibialis (0.78; SEM = 0.44; MDC95 = 1.23) were good and of acromion (ICC = 0.92; SEM = 0.15; MDC95 = 0.41) and deltoid (ICC = 0.93; SEM = 0.13; MDC95 = 0.37) were excellent. The temporal summation showed good reliability, with ICC values of 0.78 for deltoid (SEM = 0.74, MDC = 2.05) and 0.73 for tibialis anterior (SEM = 1.33, MDC = 3.69). The CPM showed good to excellent reliability, with ICC ranging from 0.84 to 0.95 (SEM: 0.41, 0.56; MDC95: 1.15, 1.57).

The procedures for the assessment of central pain processing showed good to excellent reliability. These results indicate those procedures are suitable tools for clinical pain assessment.

Clinicians should use the PPTs, temporal summation, and CPM for assessment of central pain processing in the shoulder region. In addition, clinicians should interpret the results of those procedures considering the SEM and MDC.