Influence of Pain on Exercise-induced Hypoalgesia

The Influence of Pain on Exercise-Induced Hypoalgesia in Healthy Women

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 1x3 min seated isometric knee extension exercise in healthy women. The study is a blinded 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.

Study Overview

• Status: Completed
• Conditions: Pain; Healthy
• Intervention / Treatment: Behavioral: Pain (hypertonic saline); Behavioral: No pain (Isotonic saline)

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 pressure pain thresholds (PPT) 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 Type: Interventional
• Enrollment (Actual): 34
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Denmark
  • Aalborg, Denmark, 9220
    • Dept. Of Health Science and Technology, Aalborg University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

• Pain-free
• Understands and writes Danish

Exclusion Criteria:

• Pregnancy
• Previous addictive behaviour 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 in the lower extremities within the last 12 months
• Chronic or actual pain on the days of testing
• Under the influence on the days of testing
• Inability to cooperate

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Pain (hypertonic saline); Injection (1 ml) of painful hypertonic saline (5.8%) prior to performance of the 1x3 min Seated Isometric Knee Extension	Behavioral: Pain (hypertonic saline); A bolus injection (1 ml) of hypertonic saline (5.8%) is injected into the dominant vastus medialis muscle 20 cm proximal from the basis of patella before performance of the 1x3 min Seated Isometric Knee Extension.
Placebo Comparator: No pain (isotonic saline); Injection (1 ml) of non-painful isotonic saline (0.9%) prior to performance of the 1x3 min Seated Isometric Knee Extension	Behavioral: No pain (Isotonic saline); A bolus injection (1 ml) of isotonic saline (0.9%) is injected into the dominant vastus medialis muscle 20 cm proximal from the basis of patella before performance of the 1x3 min Seated Isometric Knee Extension

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in pressure pain threshold will be assessed over the dominant quadriceps muscle	Between group comparison of the primary outcome, which is change in pressure pain threshold over the dominant quadriceps muscle before and after performing seated isometric knee extension. Pressure pain threshold is measured with a handheld pressure algometer.	Baseline, Day 2 (within 1 week of baseline), Day 3 (within 1 week of Day 2)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pressure pain threshold at the non-dominant quadriceps muscle and non-dominant trapezius muscle	Between group comparison of the secondary outcome, which is change in pressure pain threshold at the non-dominant quadriceps muscle and non-dominant trapezius muscle from before Seated Isometric Knee Extension to after Seated Isometric Knee Extension. Pressure pain threshold is measured with a handheld pressure algometer.	Baseline, Day 2 (within 1 week of baseline), Day 3 (within 1 week of Day 2)
Pain Intensity in dominant thigh	Pain intensity is assessed with numerical rating scales with 0 = no pain and 10 = maximal pain.	Assessed before and immediately after hypertonic and isotonic saline injection as well as 1, 2 and 3 minutes into the Seated Isometric Knee Extension, and immediately after the end of the seated isometric knee extension

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pressure pain threshold at the dominant and non-dominant thigh as well as non-dominant trapezius muscle	Pressure pain threshold is measured with a handheld pressure algometer.	Before and after determining maximal voluntary contraction on the fist test day and prior to saline injections
Rating of perceived exertion (RPE)	Perceived exertion is assessed with Borg RPE scale with 6 = no exertion and 20 = maximal exertion	Assessed 1, 2 and 3 minutes into the Seated Isometric Knee Extension
Quantifying the individual´s pain experience	Quantifying the individual´s pain experience will be assessed using the Pain Catastrophizing Scale (PCS) at the first session. The pain catastrophizing scale have 13 sentences regarding pain-related thoughts. Participants are asked to indicate how well each sentence applies for them: 0 = not at all, 1 = to a slight degree, 2 = to a moderate degree, 3 = to a great degree and 4 = all the time. A higher score is worse	Baseline
Pain experience	Participants will be interviewed at the end of the study regarding the experience of pain during the study. The interview will be conducted after all other experimental procedures have been completed.	Day 3 (within 2-3 weeks of the initial session)

Collaborators and Investigators

• Sponsor: Aalborg University
• Collaborators: University of Southern Denmark
• Investigators: Principal Investigator: Steffan WM Christensen, PhD, Aalborg University

Study record dates

Study Major Dates

• Study Start (Actual): March 8, 2022
• Primary Completion (Actual): April 12, 2022
• Study Completion (Actual): April 12, 2022

Study Registration Dates

• First Submitted: February 25, 2022
• First Submitted That Met QC Criteria: March 25, 2022
• First Posted (Actual): March 28, 2022

Study Record Updates

• Last Update Posted (Actual): April 20, 2022
• Last Update Submitted That Met QC Criteria: April 19, 2022
• Last Verified: April 1, 2022

More Information

Terms related to this study

• Other Study ID Numbers: S-20210184

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No