Related Experiment Video
Updated: Feb 15, 2026

Determining heat and mechanical pain threshold in inflamed skin of human subjects
Published on: January 14, 2009
A tonic heat test stimulus yields a larger and more reliable conditioned pain modulation effect compared to a phasic
Marie Udnesseter Lie1,2, Dagfinn Matre3, Per Hansson4,5
1Research and Communication Unit for Musculoskeletal Health (FORMI), Oslo University Hospital, Oslo, Norway.
Introduction:
The interest in conditioned pain modulation (CPM) as a clinical tool for measuring endogenously induced analgesia is increasing. There is, however, large variation in the CPM methodology, hindering comparison of results across studies. Research comparing different CPM protocols is needed in order to obtain a standardized test paradigm.
Objectives:
The aim of the study was to assess whether a protocol with phasic heat stimuli as test-stimulus is preferable to a protocol with tonic heat stimulus as test-stimulus.
Methods:
In this experimental crossover study, we compared 2 CPM protocols with different test-stimulus; one with tonic test-stimulus (constant heat stimulus of 120-second duration) and one with phasic test-stimuli (3 heat stimulations of 5 seconds duration separated by 10 seconds). Conditioning stimulus was a 7°C water bath in parallel with the test-stimulus. Twenty-four healthy volunteers were assessed on 2 occasions with minimum 1 week apart. Differences in the magnitude and test-retest reliability of the CPM effect in the 2 protocols were investigated with repeated-measures analysis of variance and by relative and absolute reliability indices.
Results:
The protocol with tonic test-stimulus induced a significantly larger CPM effect compared to the protocol with phasic test-stimuli (P < 0.001). Fair and good relative reliability was found with the phasic and tonic test-stimuli, respectively. Absolute reliability indices showed large intraindividual variability from session to session in both protocols.
Conclusion:
The present study shows that a CPM protocol with a tonic test-stimulus is preferable to a protocol with phasic test-stimuli. However, we emphasize that one should be cautious to use the CPM effect as biomarker or in clinical decision making on an individual level due to large intraindividual variability.
More Related Videos
10:46Using Enzyme-based Biosensors to Measure Tonic and Phasic Glutamate in Alzheimer's Mouse Models
Published on: May 3, 2017
10:50Behavioral Determination of Stimulus Pair Discrimination of Auditory Acoustic and Electrical Stimuli Using a Classical Conditioning and Heart-rate Approach
Published on: June 6, 2012
Related Concept Videos
Specific Heat
For example, increasing the temperature of one gram of water by 1°C requires one calorie of heat energy and can be written as 1 cal/g-°C, or...
Quantifying Heat
Heat Flow and Specific Heat
Heating and Cooling Curves
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
Heat Engines
Whenever we consider heat engines (and associated devices such as refrigerators and heat pumps), we do not use the standard sign convention for heat and work. For convenience, we assume that the symbols Qh, Qc, and W represent only the amounts of heat transferred...
Heat and Free Expansion