HIIT for Inflammatory-driven Shoulder Pain.

Revolutionizing Musculoskeletal Shoulder Pain Management: High-intensity Interval Training as a Systemic Intervention. A Feasibility Study.

This feasibility study investigates whether high-intensity interval training (HIIT) is feasible and acceptable for individuals with long-term shoulder pain where low-grade inflammation is suspected. Many patients do not recover fully with current local treatments, and systemic factors such as inflammation, and metabolic changes, additionally disturbances in the functioning of the nervous system often seem to play a role. HIIT is a time-efficient form of exercise that has been shown to improve inflammation and metabolic values and positively influence the balance of the nervous system. In this feasibility study, the investigators are enrolling 15 individuals with persistent shoulder pain (diagnosed with rotator cuff-related shoulder pain or frozen shoulder) with >3 months of symptoms, and 15 individuals without shoulder complaints. All participants will undergo measurements of inflammatory levels, glycosylated hemoglobin (HbA1c), blood pressure, body composition, pain sensitivity tests, and complete questionnaires about autonomic complaints and quality of life. Participants with shoulder pain will also perform one personalized HIIT session on a cycle ergometer. The investigators will assess whether participants accept a systemic intervention for their shoulder pain, if they are cooperative, and how they feel about the session; additionally, any side effects will be recorded. The aim is to determine whether HIIT is practically feasible and safe for this group and whether there are indications that systemic factors such as inflammation and nervous system function are associated with persistent shoulder pain. The outcome will determine whether follow-up research with a larger study is worthwhile.

Study Overview

• Status: Recruiting
• Conditions: Shoulder Pain; Chronic Shoulder Pain; Frozen Shoulder; Shoulder Adhesive Capsulitis; Rotator Cuff Related Shoulder Pain
• Intervention / Treatment: Other: High intensity interval training (HIIT)

Detailed Description

Persistent musculoskeletal shoulder pain, such as rotator cuff-related complaints and frozen shoulder, is common and often leads to long-term limitations and reduced quality of life. Despite available treatment options, including exercise therapy, manual techniques and infiltrations, a significant group of patients do not experience full recovery. Growing scientific evidence suggests that chronic low-grade inflammation, metabolic disorders, such as insulin resistance or obesity, autonomic dysfunction, and changes in somatosensory processing contribute to the persistence of complaints. Within this framework, physical activity is receiving more attention as a systemic intervention. High-intensity interval training (HIIT) in particular appears to have a pronounced effect on inflammatory levels, metabolic parameters, cardiovascular function, and pain modulation in various populations. HIIT also offers practical advantages due to its short duration and higher efficiency compared to traditional endurance training. Therefore, the primary aim of the current study is to investigate the feasibility of a HIIT protocol in individuals with chronic inflammatory-driven shoulder pain. This investigation includes recruitment rate, adherence, acceptance, satisfaction, motivation, safety, and practical feasibility. A secondary aim of the current study is to explore differences between individuals with shoulder pain and asymptomatic controls in terms of inflammatory markers (C-Reactive Protein), metabolic parameters (HbA1c, blood pressure, body composition), autonomic functions (self-reported symptoms, heart rate variability) and somatosensory functions (pressure pain thresholds, temporal summation and conditioned pain modulation). This is a cross-sectional feasibility study with 30 participants (15 individuals with chronic shoulder pain and 15 asymptomatic controls). The individuals with shoulder pain participate in two sessions: a maximal exercise test on a cycle ergometer (to determine VO₂max and Wmax) and a combined assessment and HIIT session. Asymptomatic controls undergo a single assessment session. The HIIT protocol consists of five one-minute intervals of cycling at 100% of the individually determined VO₂max capacity, alternating with one minute of active rest at 50% of this capacity. The total exercise time is approximately 20 minutes. The session is supervised by an experienced physiotherapist in a research setting (MOVANT, University of Antwerp). Clinical parameters that will be assessed and stored in REDCap include demographics, shoulder pain and disability (SPADI), pain intensity (VAS), quality of life (EQ-5D), inflammation (c-reactive protein), nutrition-related inflammatory index, metabolic markers (glycosylated hemoglobin, blood pressure and body composition through bioelectrical impedance), autonomic functions (self-reported autonomic symptoms and Heart Rate Variability), and somatosensory processing (pressure pain thresholds, temporal summation, and conditioned pain modulation). Results are mainly reported descriptively, with confidence intervals to estimate effect sizes. As this is a pilot study, the design is not powered for formal hypothesis testing.The study aims to investigate whether HIIT is feasible and safe in this population and to provide initial indications of the role of systemic processes in the persistence of shoulder complaints. The results may form the basis for larger randomized studies and may contribute to a paradigm shift towards systemic approaches in the treatment of musculoskeletal pain.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Michel Mertens, PhD; Phone Number: +32 3 265 89 76; Email: michel.mertens@uantwerpen.be
• Study Contact Backup: Name: Mira Meeus, PhD; Email: mira.meeus@uantwerpen.be

Study Locations

• Belgium
  • Wilrijk, Belgium, 2610
    • Recruiting
    • Universiteit Antwerpen
    • Contact: Michel Mertens, PhD; Phone Number: +32 3 265 89 76; Email: michel.mertens@uantwerpen.be
    • Sub-Investigator: Mira Meeus, PhD
    • Sub-Investigator: An De Groef, PhD
    • Sub-Investigator: Jonas Verbrugghe, PhD
    • Sub-Investigator: Sebastiaan Dalle, PhD
    • Sub-Investigator: Lisa Van Hecke
    • Sub-Investigator: Niels Polfliet
    • Sub-Investigator: Chloe Van Der Auwera
    • Sub-Investigator: Lennert Moons
    • Sub-Investigator: Tom Philips
    • Sub-Investigator: Levi Peeters

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Shoulder pain group

• Shoulder pain > 3 months
• Diagnosis of rotator cuff related shoulder pain or frozen shoulder
• Understanding Dutch in speaking and writing.

Control group

o Understanding Dutch in speaking and writing

Exclusion Criteria:

Shoulder pain group

• <18 years
• Shoulder surgery or trauma in past year
• Neurological, cancer, or neuromuscular disease
• Osteoarthritis, cervical or AC joint pathology
• Heavy physical exertion <48h before testing

Control group

• <18 years
• recent or recurrent neck/shoulder pain
• systemic or neurological disease
• psychiatric disorders
• pregnancy/breastfeeding
• pain medication <48h before test

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High intensity interval training (HIIT); One 20-minute HIIT session (5x1 min at VO₂max with 1 min recovery at 50% VO₂max) on cycle ergometer	Other: High intensity interval training (HIIT); One 20-minute HIIT session (5x1 min at VO₂max with 1 min recovery at 50% VO₂max) on cycle ergometer.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Participant acceptance and satisfaction	Participant acceptance and satisfaction of the HIIT-session will be assessed with an adapted short questionnaire based on the total shoulder arthroplasty postoperative satisfaction questionnaire.	Immediately after the HIIT training session
HIIT protocol adherence	HIIT protocol adherence will be assessed by determining the percentage of HIIT-protocol completers and registration of protocol adjustments.	During the training session
Intrinsic motivation	Intrinsic motivation of the participants with shoulder pain will be assessed using the intrinsic motivation inventory (IMI). From this questionnaire only the following domains will be questioned: interest/enjoyment, effort, and value/usefulness. The questions will be adapted specific to the current study, as recommended.	Immediately after the training session
Study recruitment rate	Study recruitment rate will be determined by dividing the number of participants by the number of contacted individuals. Reasons for non-participation will be assessed with preset response options.	During the study period
Full protocol conduction	Assessment of full protocol conduction will be assessed by registering preparation time, protocol duration, and issues with equipment and location.	Immediately after the assessment and training session
Adverse events	The severity of the adverse event will be determine based on the Common Terminology Criteria for Adverse Events (CTCAE).	Up to 3 days after training and assessment

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Shoulder pain and disability	The shoulder pain and disability index (SPADI) will be used, this is a self-reported index that consists of 13 items in two domains (pain (5 items) and disability (8 items)). A percentage ranging from 0 (no pain or disability) to 100 (worst pain or disability) will be used to present the pain and disability experienced by the participants. The SPADI has been found valid and reliable in evaluating pain and disability in shoulder disorders.	Baseline
Pain intensity	Pain intensity will be measured by a visual analogue scale. Participants will be asked to rate their pain on a 10 cm line by drawing a vertical mark on that line. The left end of the line represents 'No pain' (0 cm) and the right end 'Most severe pain' (10 cm). The scoring is the distance (in millimeter) from the left end of the line to the vertical mark of the participant. Participants must rate their shoulder pain for three moments: current and minimal and maximal pain during the last week. The VAS has been found valid and reliable.	Baseline
Health-related quality of life	Health-related quality of life will be assessed with the EQ-5D. The EQ-5D is a standardized, validated measure comprising five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is rated on a five-level ordinal scale (from 'no problems' to 'extreme problems'), offering improved sensitivity and reduced ceiling effects compared to the earlier 3-level version. Additionally, the EQ-5D includes a visual analogue scale (EQ-VAS), on which participants rate their overall health on a scale ranging from 0 ("the worst health you can imagine") to 100 ("the best health you can imagine"). The psychometric properties of the EQ-5D are excellent in a broad range of populations, conditions and settings. Utility scores will be calculated using the Dutch EQ-5D value set.	Baseline
C-reactive protein level	C-reactive protein (CRP) level will be measured by the QuikRead go easy CRP, a highly sensitive tool. With 10 μL blood (fingerprick) the level of CRP between 1 and 120 mg/L can be determined within 5 minutes. This tool has been found reliable.	Baseline
Adapted dietary inflammatory index	The adapted dietary inflammatory index (ADII) will be based on data acquired through the food frequency questionnaire (FFQ), as conducted previously. The ADII is a literature-derived index that summarizes an individual's diet on the continuum from maximally anti-inflammatory to maximally pro-inflammatory. ADII was calculated by multiplying the dietary inflammatory weights of the dietary components by the daily intake.	Baseline
Glycosylated hemoglobin	Glycosylated hemoglobin (HbA1c) will be measured with the A1CNOW+ tool. The A1CNOW+ is a tool that measures the A1c and total hemoglobin and determines the percentage HbA1c over the last 90 days, which is valid and reliable.	Baseline
Blood pressure	Blood pressure will be measured using an automated office blood pressure monitor in a seated position in a quit examination room. Both diastolic and systolic pressure will be recorded.	Baseline
Body composition	Body composition will be determined by the InBody 770® (InBodyUSA, Cerritos, CA), more specifically %body fat and fat free mass of the participants will be determined.	Baseline
Self-reported autonomic symptoms	Self-reported autonomic symptoms will be assessed by the composite autonomic symptom score 31 (COMPASS-31), which has 31 questions in six domains (orthostatic intolerance, vasomotor, secretomotor, gastrointestinal, constipation, bladder, and pupillomotor). Total score ranges from 0 to 100 because of summation of the six subdomains.	Baseline
Vasomotor function	Vasomotor function of the autonomic nervous system (parasympathetic branch) will be measured with the help of resting heart rate variability (HRV), which will be measured using a chest strap (polar H10). The root mean square of successive RR-interval differences (RRSMD), mean RR interval, standard deviation of all normal RR intervals (SDNN), and percentage of successive RR intervals that differ by more than 50 ms (pNN50) will be determined.	Baseline
Primary and secondary hyperalgesia	Primary and secondary hyperalgesia (in kg/cm2) will be assessed by pressure pain thresholds (PPTs). The PPTs will be determined at both affected and unaffected (shoulder pain group) and dominant and non-dominant (control group) shoulders and affected side (shoulder pain group) or dominant (control group) quadriceps muscle.	Baseline
Temporal summation	Temporal summation will be induced with a train of 10 repeated pressure stimuli at the quadriceps muscle at the affected (shoulder pain group) or dominant (control group) side using a digital algometer. Pressure will be applied with 2 kg/s with 1-second interstimulus intervals. The pressure for temporal summation will be the mean PPT previously determined for the quadriceps. Participants rate their pain intensity on a NRS (0-10) after the first, fifth, and tenth repetition of the train stimuli. Temporal summation is calculated as the difference in pain intensity between the tenth and the first pulse	Baseline
Conditioned pain modulation	The test stimulus consists of mechanical pressure pain elicited (PPT). The conditioning stimulus consists of ischemic occlusion and will be applied to the unaffected (shoulder pain group) or non-dominant (control group) arm with an inflatable air cuff (Boso Profitest). The absolute conditioned pain modulation effect will be calculated as the difference between the PPT at baseline and the PPT with conditioning stimulus, while the relative effect will be calculated as follows: (PPT at baseline - PPT with conditioning stimulus) / PPT at baseline.	Baseline

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gender	The gender of the participant	Baseline
Age	The age of the participant	Baseline
Job status	The job status of the participant	Baseline
Alcohol abuse	The alcohol abuse status of the participant	Baseline
Smoking status	Smoking status of the participant	Baseline
Comorbidities	Presence and type(s) of comorbidities of the participant	Baseline
Disorder characteristics	Characteristics of the disorder the participant presents with	Baseline

Collaborators and Investigators

• Sponsor: Universiteit Antwerpen
• Investigators: Principal Investigator: Michel Mertens, PhD, Universiteit Antwerpen

Study record dates

Study Major Dates

• Study Start (Actual): December 10, 2025
• Primary Completion (Estimated): April 1, 2026
• Study Completion (Estimated): October 1, 2026

Study Registration Dates

• First Submitted: November 17, 2025
• First Submitted That Met QC Criteria: November 28, 2025
• First Posted (Actual): December 10, 2025

Study Record Updates

• Last Update Posted (Actual): February 13, 2026
• Last Update Submitted That Met QC Criteria: February 10, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: metabolic syndrome; low-grade inflammation; high intensity interval training; chronic shoulder pain; autonomic dysfunction; frozen shoulder; rotator cuff related shoulder pain
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Musculoskeletal Diseases; Nervous System Diseases; Joint Diseases; Metabolic Diseases; Glucose Metabolism Disorders; Insulin Resistance; Hyperinsulinism; Arthralgia; Autonomic Nervous System Diseases; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Metabolic Syndrome; Bursitis; Shoulder Pain; Primary Dysautonomias; Motor Activity; Movement; Musculoskeletal Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena; Physical Conditioning, Human; Exercise; High-Intensity Interval Training
• Other Study ID Numbers: 7796

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: The results of the food frequency questionnaire, which is part of the nutritional inflammatory index, will be shared with the developers of the questionnaire for optimization of the questionnaire. Furthermore, all data can be shared with other researchers upon reasonable request. Data will not be publicly available.
• IPD Sharing Time Frame: It will only be available upon reasonable request.
• IPD Sharing Access Criteria: The requested data will be send to the requester by the PI of the study and a data sharing agreement will be signed by both parties.

Drug and device information, study documents

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