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NCT Number: NCT07327593

Exercise Induced Hypoalgesia in Pain-free Stroke and Healthy Populations: a Cohort Study

Exercise has shown multiple beneficial effects in both healthy and post-stroke populations. One of these is the acute reduction in sensitivity to painful stimuli, called exercise-induced hypoalgesia (EIH). This phenomenon has been studied since 1979 and has shown improvements in pain thresholds with both aerobic and resistance training in healthy, pain-free populations and different chronic pain conditions.

Although there has been extensive research on EIH in healthy populations and those with chronic musculoskeletal pain, surprisingly little attention has been given to individuals with neurological pathologies. Chronic pain is found in more than 50% of patients after stroke, and 70% of affected individuals experience pain on daily activities. Reported prevalences of post-stroke pain (PSP) between different studies, but there is a general consensus that it is an underreported phenomenon. Patients with pain experience greater cognitive and functional decline, fatigue, depression and lower quality of life.

Multiple factors contribute to PSP, and various approaches exist to treat all the variables influencing it. This study aims to compare the effects of exercise on pain perception in healthy individuals and stroke patients without pain, using the same cardiovascular training protocol, to better understand the mechanisms of EIH and its maintenance after stroke, ultimately aiming to improve the treatment of people with stroke.

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Key information

Conditions

Stroke Brain Diseases Cardiovascular Diseases Central Nervous System Diseases Cerebrovascular Disorders Exercise Induced Hypoalgesia Nervous System Diseases Neurologic Manifestations Pain Pathological Conditions, Signs and Symptoms Signs and Symptoms Vascular Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Neuron Madrid Río, Madrid, Spain

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Healthy cohort:

Age > 18 years
No neurological damage
No medical conditions that could affect the test

Post-stroke cohort:

Age > 18 years
Ischemic or hemorrhagic stroke (time since onset > 3 months)

Exclusion criteria

Healthy cohort:

Any medical condition that could affect the test (respiratory, cardiovascular, metabolic diseases, for example)
Pain in any location, of duration > 1 week in the 3 months preceding the trial.

Post-stroke cohort:

Unable to participate in the test (no possibility of transfer or active pedaling)
Medical contraindication to cardiovascular training for any reason
Inability to follow instructions or communicate sensations during training
Other neurological pathology, cardiac pathology (unstable angina, arrhythmias, aortic or left ventricular problems, myocarditis, pericarditis), pulmonary pathology that affects the test (pulmonary embolisms, pulmonary hypertension, etc.), renal or metabolic problems (severe renal dysfunction, uncontrolled diabetes, etc.), acute infection or fever, neurosurgery within 6 weeks prior to inclusion in the study
Pain in any location, lasting > 1 week in the 3 months prior to the trial.
Use of beta-blockers, antidepressants, or any medication that may alter heart rate measurements

Treatment and study plan

Cardiovascular training

Other

The cardiovascular training protocol will consist of a 5-minute warm-up aimed at reaching 70% of maximum heart rate (MHR) followed by 20 minutes of sustained work at this intensity (since maintaining this intensity is difficult, especially in the stroke cohort, we will allow for a margin of ±2-3% of MHR and provide feedback to increase or decrease the heart rate). We will aim to keep the heart rate below 73% of maximum heart rate, maintain blood pressure within safe ranges, and keep the effort level between 14/20 and 16/20

Primary outcomes

Pressure pain thresholds

Time frame: Before the cardiovacular training, inmediately after the training, and 30 minutes after

Pressure pain thresholds (PPT) are the most used pain sensitivity measure for these paradigms, and represent a static measure of pain, indicating the basal state of pain perception. It is usually measured with an algometer, which is pressured into the body of the participant, who is informed to warn in the moment when pressure starts to be painful. EIH has shown little differences between local and general effects, so we will measure PPT in both rectus femoris (local effects) and first dorsal interosseous (general effects), marking the exact points for ensuring the replicability of the measure after the exercise program. In the post-stroke cohort, this assessment will be performed on the non-paretic side, so that the possible loss of sensitivity due to the condition does not influence the measurements.
Conditioned pain modulation

Time frame: Before the cardiovascular training, inmediately after the training and 30 minutes after

Conditioned pain comulation (CPM) is the terminology used to describe the effect of endogenous pathways to enhance or diminish the afferent noxious stimuli. For this assessment the "cuff test" methodology will be carried out over the healthy arm of post-stroke participants. This methodology employs a test stimulus (TS) using pressure pain threshold measurement. Subsequently, an inflatable pressure cuff is applied, and its pressure is increased until the patient reports a pain sensation of 6 out of 10. While the cuff is inflated, the pressure pain threshold measurement is repeated to obtain a a conditioned stimulus (CS). The test result is then calculated by subtracting the pressures obtained on the algometer, thus calculating the CS-TS difference.

CPM will be measured in the dominant side in the healthy cohort and in the healthy side in the post-stroke cohort.

Study contacts

Contact information is provided by the study sponsor or research team.

Alejandro Herrera Rojas, Physical Therapist

CONTACT

[email protected]

+ 34 640944777

Alfredo Lerín Calvo, Physical Therapist

CONTACT

[email protected]

+ 34 620187457

Sponsors and collaborators

Lead sponsor

Neuron, Spain

Other

Registry information

Important dates

Study start: 2026
Primary completion: 2026
Study completion: 2026
First posted: Jan 8, 2026
Registry last updated: Mar 20, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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Completed