Influence of Pain on Exercise-induced Hypoalgesia

Aalborg University

Status: Completed

Conditions: Healthy; Pain

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

Study type: Interventional

Funder types: Other

Identifiers

NCT05299268

S-20210184

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 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.

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 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.

Enrollment: 34 patients

Sex: Female

Ages: 18 to 50 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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34 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 1x3 min Seated Isometric Knee Extension

Treatment:

Behavioral: Pain (hypertonic saline)

No pain (isotonic saline)

Placebo Comparator group

Description:

Injection (1 ml) of non-painful isotonic saline (0.9%) prior to performance of the 1x3 min Seated Isometric Knee Extension

Treatment:

Behavioral: No pain (Isotonic saline)