Influence of Pain on Exercise-induced Hypoalgesia

Not Applicable

Completed

• Conditions: Pain
• Interventions: Behavioral: No pain (Hypotonic saline); Behavioral: Pain (hypertonic saline)

• Registration Number: NCT04354948
• Lead Sponsor: Odense University Hospital

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.

Study Timeline

• Study First Submitted: 2020-04-17
• Study First Submitted QC: 2020-04-17
• Study First Posted: 2020-04-21
• Study Start: 2020-06-19
• Status Verified: 2020-09
• Primary Completion: 2020-09-14
• Study Completion: 2020-09-14
• Last Update Submitted: 2020-09-21
• Last Update Posted: 2020-09-22

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 35

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
No pain (Hypotonic saline)	No pain (Hypotonic saline)	Injection (1 ml) of non-painful isotonic saline (0.9%) prior to performance of the 3 min wall squat exercise
Pain (hypertonic saline)	Pain (hypertonic saline)	Injection (1 ml) of painful hypertonic saline (5.8%) prior to performance of the 3 min wall squat exercise

Primary Outcome Measures

Name	Time	Method
Pressure pain threshold at the right quadriceps muscle where injection is performed.	Before and after the 3 minutes wall squat	Between group comparison of the primary outcome, which is change in pressure pain threshold at the right quadriceps muscle from before wall squat to after wall squat. Pressure pain threshold is measured with a hand held pressure algometer.

Secondary Outcome Measures

Name	Time	Method
Pressure pain threshold at the non-dominant trapezius muscle	Before and after the 3 minutes wall squat	Between group comparison of the secondary outcome, which is change in pressure pain threshold at the left trapezius muscle from before wall squat to after wall squat. Pressure pain threshold is measured with a hand held pressure algometer.
Pressure pain threshold at the left quadriceps muscle where injection is not performed.	Before and after the 3 minutes wall squat	Between group comparison of the secondary outcome, which is change in pressure pain threshold at the left quadriceps muscle from before wall squat to after wall squat. Pressure pain threshold is measured with a hand held pressure algometer.
Pain Intensity in thighs	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	Pain intensity in both thighs are assessed with numerical rating scales with 0 = no pain and 10 = maximal pain.

Trial Locations

Locations (1)

Pain Center, University Hospital Odense; 🇩🇰 Odense, Funen, Denmark