Clinical trial NCT04354948: Influence of Pain on Exercise-induced Hypoalgesia
Official title: The Influence of Pain on Exercise-Induced Hypoalgesia in Healthy Subjects: A Randomized Controlled Trial
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Pain
Keywords: Exercise-induced hypoalgesia
Pressure pain threshold
hypertonic saline
Lead sponsor: Odense University Hospital
Sponsor class: OTHER
Collaborators: name: Aalborg University
First posted: 2020-04-21
Enrollment: 35
Sex: ALL
Minimum age (years): 18
Maximum age (years): 50
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: This study is a 2-arm randomized controlled cross-over trial with 1 week between arms
Primary purpose: BASIC_SCIENCE

Brief summary: The purpose of this study is to investigate how acute pain induced by hypertonic saline prior to exercise influence the magnitude of exercise-induced hypoalgesia after a 3 min isometric wallsquat exercise in healthy subjects. The study is a single blinded (investigator) randomized cross-over trial The results from the study may be of great importance to the understanding of exercise-induced hypoalgesia, and whether the presence of pain affects the effects of exercise.

Detailed description: Exercise is recommended to promote and maintain health and as treatment for more than 25 chronic diseases and pain conditions.

The mechanisms underlying pain relief of exercise are largely unknown but may be related to the modulation of central descending pain inhibitory pathways after acute exercise bouts. Exercise-induced hypoalgesia (EIH) is typically assessed as the temporary change in PPTs after a short acute exercise bout and EIH is seen as a proxy of descending pain inhibitory control. In general, EIH seems hypoalgesic (functional) in asymptomatic subjects. A hyperalgesic (impaired) EIH response has been reported in different chronic pain populations, although a functional EIH response also has been reported in subgroups of knee osteoarthritis patients. This implies differences in the acute response to exercise between healthy (pain-free) subjects and chronic pain patients, but it is still unknown whether the presence of pain itself affects the pain alleviating response (i.e. the EIH response) to acute exercise.

It is hypothesized that acute pain will decrease the EIH response magnitude following hypertonic saline injection compared with the control injection. This study will increase the insight into the EIH mechanisms in healthy subjects in general, and how the presence of pain affects the body's own ability to modulate pain during exercise.

Eligibility criteria: Inclusion Criteria:

* Pain-free
* Understands and writes Danish

Exclusion Criteria:

* Pregnancy
* Previous addictive behavior defined as abuse of hash, opioids or other euphoric substances.
* Previous painful or mental illnesses, neurological or circulatory diseases in the form of heart or lung disease.
* Surgery within last 3 months
* Pain on the days of testing
* Pain for more than 2 weeks within the last 3 months

Primary outcomes:
measure: Pressure pain threshold at the right quadriceps muscle where injection is performed.
timeFrame: Before and after the 3 minutes wall squat
Secondary outcomes:
measure: Pressure pain threshold at the non-dominant trapezius muscle
timeFrame: Before and after the 3 minutes wall squat
measure: Pressure pain threshold at the left quadriceps muscle where injection is not performed.
timeFrame: Before and after the 3 minutes wall squat
measure: Pain Intensity in thighs
timeFrame: Assessed before and immediately after hypertonic and isotonic saline injection as well as after 1, 2 and 3 min of wall squat, and immediately after the end of wall squat
Other outcomes:
measure: Pressure pain threshold
timeFrame: At baseline on both days before saline injections
measure: Pressure pain tolerance
timeFrame: At baseline on both days before saline injections
measure: Temporal summation of pain
timeFrame: At baseline on both days before saline injections
measure: International Physical Activity Questionnaire (IPAQ)
timeFrame: Baseline of first session
Locations:
city: Odense
country: Denmark
facility: Pain Center, University Hospital Odense
state: Funen
Study officials:
affiliation: Odense University Hospital
name: Henrik B Vægter, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Hansen S, Petersen KK, Sloth E, Manum LA, McDonald AK, Andersen PG, Vaegter HB. Hypoalgesia after exercises with painful vs. non-painful muscles in healthy subjects - a randomized cross-over study. Scand J Pain. 2021 Dec 27;22(3):614-621. doi: 10.1515/sjpain-2021-0161. Print 2022 Jul 26.