Influence of Pain on Exercise-induced Hypoalgesia

Odense University Hospital

Status: Completed

Conditions: Pain

Treatments: Behavioral: No pain (Hypotonic saline); Behavioral: Pain (hypertonic saline)

Study type: Interventional

Funder types: Other

Identifiers

NCT04354948

S-20190081

Details and patient eligibility

About

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.

Full 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.

Enrollment: 35 patients

Sex: All

Ages: 18 to 50 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

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35 participants in 2 patient groups, including a placebo group

Pain (hypertonic saline)

Experimental group

Description:

Injection (1 ml) of painful hypertonic saline (5.8%) prior to performance of the 3 min wall squat exercise

Treatment:

Behavioral: Pain (hypertonic saline)

No pain (Hypotonic saline)

Placebo Comparator group

Description:

Injection (1 ml) of non-painful isotonic saline (0.9%) prior to performance of the 3 min wall squat exercise

Treatment:

Behavioral: No pain (Hypotonic saline)