Temporal summation is a mechanism that enhances pain perception. It is a natural mechanism present in most individuals. Generally, temporal summation is measured by the application of a moderately painful stimulation for several seconds.However, there is still no official recommendation in the literature. There is therefore a great disparity in the protocols. Some studies apply thermal stimulation (heating the skin) while others apply mechanical stimulation (applying pressure). Another point of contention is that some studies apply continuous stimulation for 2 minutes while others apply a series of several small stimulation of 1 second). Between these studies, the amplitude of temporal summation varies according to the stimulation performed. Note also that the study population is also very different between studies. In these conditions, it remains difficult to know the impact of the nature of the stimulation on the measured amplitude of the temporal summation.

Objective: To determine the effect of the nature and frequency of the stimulation used to measure one of the physiological mechanisms of pain

Methods: In order to meet the objective, 34 pain-free participants will be recruited (17 females and 17 males) between the ages of 18 and 30 years. A single visit will be proposed (approximately 1 h). Each participant will be stimulated with 4 stimulation conditions:

• continuous thermal (1 stimulation of two minutes)
• repetitive thermal (30 stimulations of 1 second)
• continuous mechanical (1 stimulation of two minutes)
• repetitive mechanical (30 stimulation of 1 second) In order to control certain psychological parameters, questionnaires measuring anxiety, depression and fear of pain will be administered. This will allow the investigation team to perform subgroup analyses if necessary. A repeated measures analysis of variance will be performed to meet the objective.

Anticipated Results: The objective of this project is to determine the impact of different stimuli on the measurement of a pain mechanism. In this sense, the results will be important since they will allow to develop recommendations to optimize the measurement of this mechanism.

Inclusion Criteria:

• Subjects aged 18 to 30 years, able to consent (understand English or French)
• No chronic pain
• No primary sensory disorders

Exclusion Criteria:

• Presence of upper extremity injuries
• Absence of anxiety symptoms (HADs Score < 6) (Appendix 1)
• Presence of cardiovascular disease / neurocognitive disorders / mental illness
• Pregnant or postpartum women less than one year old

For this project, healthy males and females (1:1 ratio) between the ages of 18 and 30 will represent our target population