P4ACE Trial for Persons With Chronic Knee Pain (P4ACE)

July 23, 2025 updated by: Northwestern University

Pain Profiles and Patterns of Physical Activity in Persons With Chronic Knee Pain

The goal of this single-blind, cross-over clinical trial is to compare the immediate effect of intermittent vs. continuous walking on clinical and mechanistic pain profiles in persons with knee osteoarthritis (OA). In this cross-over trial, participants will perform two types of walking on a treadmill. Intermittent walking will involve 3 blocks of 10 minutes with 2 blocks of 5-minute rest (sitting on a chair) in-between. Continuous walking will involve resting for 10 minutes (sitting in a chair) before walking on the treadmill for 1 continuous block of 30 minutes.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The study objectives are to compare the immediate effect of intermittent vs. continuous walking on clinical and mechanistic pain profiles in persons with knee osteoarthritis (OA). The investigators hypothesize that continuous walking will result in greater increases in clinical pain and mechanistic pain sensitivity than intermittent walking. Physical activity (PA) has been recommended as the first-line management strategy for people with chronic knee pain. Walking is an accessible, low-cost, joint-friendly form of PA and is widely advocated for older adults with knee complaints. However, movement-evoked pain is a commonly cited barrier for PA engagement. On one hand, a bout of PA may produce short-term analgesia and reduce pain. On the other hand, excessive or prolonged PA may exacerbate symptoms and lead to avoidance/fear of subsequent PA. Besides the total PA volume, how it is accumulated could also impact joint health. It is biomechanically plausible that shorter and frequent activities are more beneficial to articular tissues than longer and infrequent activities. Compared to intermittent loading, prolonged continuous loading had a detrimental effect on the biomechanical functions of articular cartilage in a bovine model. Findings of this study will provide insight on the relations between patterns of PA and pain profiles.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
23

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Denmark
      • Aalborg, Denmark
        • Aalborg University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

45 years to 75 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • men or women aged 45-75 years
  • BMI ≤ 35 kg/m2
  • frequent movement-related knee pain (knee pain on more than half the days of the past month)
  • no morning stiffness or morning stiffness lasting < 30-min
  • self-reported unilateral or bilateral knee pain of ≥ 3 and ≤ 7 on a 0-10 numeric pain rating scale (NPRS)
  • knee pain duration ≥ 12 months
  • physically able to walk unassisted on a treadmill at ≥ 4 km/hour for 30 minutes
  • own a smart phone
  • willing and able to wear an activity monitor and answer electronic survey questions delivered via a smart phone over a 10-day period.

Exclusion Criteria:

  • intra-articular steroid injections in the previous 3 months
  • intra-articular hyaluronic acid injection in the previous 6 months
  • any arthroscopic or surgical knee procedures (e.g., partial meniscectomy) in the past 12 months
  • lumbar radiculopathy
  • neurological, vestibular, or visual dysfunction affecting walking balance and mobility
  • plan for total knee arthroplasty in the next 12 months

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Intermittent Walking
Intermittent walking on the treadmill
Other: Intermittent Walking
Wearing comfortable clothes and their usual walking shoes, participants will walk on a treadmill to accrue 30 minutes of walking. Participants will be instructed not to use the treadmill side rails for balance or support during walking. Participants will walk on the treadmill for 3 blocks of 10 minutes with 2 blocks of 5-minute rest (sitting on a chair) in-between. A safety button to stop the treadmill will be available to the participants, so they can stop walking anytime. If participants feel that they are about to lose balance, they are allowed to hold on to the side rails to regain balance and terminate the trial.
Active Comparator: Continuous Walking
Continuous walking on the treadmill
Other: Continuous Walking
Wearing comfortable clothes and their usual walking shoes, participants will walk on a treadmill to accrue 30 minutes of walking. Participants will be instructed not to use the treadmill side rails for balance or support during walking. Participants will rest for 10 minutes (sitting in a chair) before walking on the treadmill for 1 continuous block of 30 minutes. A safety button to stop the treadmill will be available to the participants, so they can stop walking anytime. If participants feel that they are about to lose balance, they are allowed to hold on to the side rails to regain balance and terminate the trial.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change from pre-walking to immediately post-walking in Numeric Pain Rating Scale (NPRS) for current knee pain
Time Frame: pre-walking, immediately post-walking
The primary outcome is the self-reported clinical pain. The pre- and post-walking knee pain will be rated right before the commencement of the walking program and at the termination of the walking program respectively. Participants verbally select a value that corresponds with the intensity of pain that they experience. "0" means "no pain" and "10" means "pain as bad as you can imagine" or "worst pain imaginable". The NPRS, an 11-point (i.e., 0-10) measure of pain intensity, is recommended as a core outcome measure in clinical trials of chronic pain treatments and has excellent reliability and validity for adults with chronic musculoskeletal pain. On average, a change of 2 points or a change of approximately 30% in NPRS represented a clinically important difference in adults with chronic pain.
pre-walking, immediately post-walking

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change from pre-walking to immediately post-walking in Cuff Pain Detection Threshold (cPDT)
Time Frame: pre-walking, immediately post-walking
A computer-controlled cuff algometer will measure cPDT. Participants will be fitted with 13-cm-wide silicone tourniquet cuffs (VBM, Düsseldorf, Germany) on bilateral lower limbs. The cuff inflation will be controlled by a cuff algometry system (Cortex Technology, Hadsund, Denmark). The cuff will be inflated at a rate of 1kPa/s to a maximum of 100 kPa. Using a hand-held electronic device with a release button for deflating the cuff, participants will be instructed to rate the pressure pain continuously on a 10-cm visual analogue scale (VAS), until the pain becomes intolerable, at which point they will press the release button to terminate the test. The cPDT will be the cuff pressure reading at the time of VAS rating of 1cm. The cuff-system is user independent and has been shown to be reliable for the outcomes assessed.
pre-walking, immediately post-walking
Change from pre-walking to immediately post-walking in Cuff Pain Tolerance Threshold (cPTT)
Time Frame: pre-walking, immediately post-walking
A computer-controlled cuff algometer will measure cPDT. Participants will be fitted with 13-cm-wide silicone tourniquet cuffs (VBM, Düsseldorf, Germany) on bilateral lower limbs. The cuff inflation will be controlled by a cuff algometry system (Cortex Technology, Hadsund, Denmark). The cuff will be inflated at a rate of 1kPa/s to a maximum of 100 kPa. Using a hand-held electronic device with a release button for deflating the cuff, participants will be instructed to rate the pressure pain continuously on a 10-cm visual analogue scale (VAS), until the pain becomes intolerable, at which point they will press the release button to terminate the test. The cPTT will be the cuff pressure reading at the time of test termination (i.e., when the pain becomes intolerable). If the tolerance threshold is not achieved before the 100 kPa limit, cPTT will be 100 kPa. The cuff-system is user independent and has been shown to be reliable for the outcomes assessed.
pre-walking, immediately post-walking
Change from pre-walking to immediately post-walking in Temporal Summation of Pain (TSP)
Time Frame: pre-walking, immediately post-walking
Using the same cuff algometry system, the TSP will be assessed by delivering 10 rapid cuff pressure stimuli at a pressure magnitude of the cPTT lasting for one second. Each stimulus will be followed by 1-second break before the next stimulus. Participants will be instructed to rate the pain intensity on the electronic VAS for each stimulus without returning the VAS to zero between inflations. The VAS score will be recorded for each stimulus. This procedure has been shown to be reliable with Intraclass Correlation Coefficients of 0.70-0.77.
pre-walking, immediately post-walking
Change from pre-walking to immediately post-walking in Conditioned Pain Modulation (CPM)
Time Frame: pre-walking, immediately post-walking
The CPM will be assessed by re-measuring the cPDT of the index limb during a simultaneously painful conditioning stimulus on the non-index limb. An increase in cPDT from baseline would indicate a CPM response.
pre-walking, immediately post-walking

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Northwestern University

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Aalborg University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Alison H Chang, Aalborg University
  • Study Director: Michael Rathleff, Aalborg University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 20, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 31, 2024

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 31, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 12, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 12, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 21, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 28, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 23, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • N-20220047

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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Cookie Settings

We use cookies to ensure that we give you the best experience on our website. For more details carefully read our Privacy and Cookies Policy. ...>>>You can change your preferences or withdraw your consent at any time by deleting the cookies from your website or computer as described in the policy. Please accept it and choose your preferences by ticking the corresponding boxes in the "Manage Settings" section below. Please carefully read our Terms of Service before you proceed with using any part of this website.
«Manage Settings