Mechanisms of Exercise-induced Hypoalgesia

Disentangling Peripheral and Central Mechanisms of Exercise-induced Hypoalgesia in Healthy Adults Males.

This project aims to clarify the mechanisms underpinning the acute analgesic effect of exercise in healthy humans-a phenomenon called "Exercise-induced hypoalgesia" (EIH). This study will characterize, using a within-subject cross-over design, the effects of a single session of aerobic exercise vs. a control condition on the sensitivity to stimuli preferentially activating mechano vs. heat-sensitive nociceptors of the skin vs. muscle, within vs. outside exercising body parts. The investigators hypothesize (1) that EIH will be greater in the exercise session compared to the control session, (2) that EIH will be greater at the local site compared to the remote site if local changes in nociceptive sensitivity contribute to EIH, and (3) that exercise will preferentially affect blunt pressure-induced pain if EIH involves specific changes in sensitivity of muscle nociceptors.

Inclusion Criteria:

• Males aged between 18 and 30 years
• Lack of risks for physical exercise assessed using the Physical Activity Readiness Questionnaire (PAR-Q)
• Ability to provide written informed consent
• Fluency in French
• BMI between 17 and 30

Exclusion Criteria:

• Regular tobacco use
• Not willing or able to abstain from alcohol, recreational drugs, coffee, or tea from 24 hours prior to each experimental session.
• Not willing or able to restrain from physical activity > 24h prior to each experimental session, and to be in a fasted state on the day of each experimental session.
• Any neurological, cardio-vascular, respiratory, inflammatory, endocrine, psychiatric, oncological, rheumatological conditions. Such condition could put the participants at risk during maximal exercise testing and/or interfere with pain assessment.
• Presence of any medical devices (e.g., cardiac pacemaker) implants or prothesis unless it is beyond discussion that these will not put the subject's safety during the study at risk and will not interfere with the results of the study.
• Any chronic pain condition or recent history thereof (i.e. within the preceeding 2 years).
• Wounds or skin alteration on testing sites.
• Impaired hearing. This would affect ability to detect the control auditory stimuli.
• Surgery < 12 months
• Any drug intake in the past 2 weeks including antibiotics, herbal medicines and other remedies except the following drugs that will be allowed up to 48 hours prior to the experiments: oral paracetamol or ibuprofen for a self-limiting condition (e.g. toothache, bruise). Oral antihistaminics and nasal aerosol and topical treatments for seasonal allergy up to 1 week before the experimental session.
• Any physical activity contraindication