Knee Osteoarthritis Rehabilitation Through Rotational Inertia (KORRI)

Exploring the Benefits of Eccentric Training for Aging Adults With Knee Osteoarthritis

This study is testing whether a new type of exercise program, called eccentric overload training using a flywheel device, can improve stair-climbing ability in people with knee osteoarthritis. The flywheel device provides resistance throughout the entire movement and gives extra challenge during the muscle-lengthening phase of exercise. This type of training may improve muscle structure, strength, and coordination more effectively than conventional methods.

The study's central idea is that better muscle quality and improved coordination will lead to smoother, safer stair movement and reduce the risk of falls. Advanced tools such as ultrasound imaging and motion analysis will be used to measure muscle health and movement patterns in detail.

The hypothesis is that individuals with knee osteoarthritis have poorer muscle quality and less coordinated stair-stepping compared to healthy adults, and that performing eccentric overload training will enhance muscle quality, improve movement coordination, and make stair navigation safer and more efficient.

Study Overview

• Status: Recruiting
• Conditions: Knee Arthritis, Osteoarthritis
• Intervention / Treatment: Other: Eccentric resistance training

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Katie Boncella, MS; Phone Number: 7207241786; Email: katie.boncella@cuanschutz.edu
• Study Contact Backup: Name: Michael Harris-Love, PT, MPT, DSc, FGSA, FAPTA; Phone Number: 303-724-0687; Email: michael.harris-love@cuanschutz.edu

Study Locations

• United States
  • Colorado
    • Aurora, Colorado, United States, 80045
      • Recruiting
      • University of Colorado, Denver
      • Contact: Katie Boncella; Phone Number: 720-724-1786; Email: katie.boncella@cuanschutz.edu
      • Principal Investigator: Michael Harris-Love, PT, MPT, DSc, FGSA, FAPTA

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria Osteoarthritis (OA) Group:

• Aged 40-70 years
• Radiographically confirmed knee OA (Kellgren-Lawrence [KL] Grade 2 or 3)
• Able to walk independently (assistive devices permitted)

Inclusion Criteria Healthy Control Group:

• Aged 40-70 years
• No radiographic evidence of knee OA (KL Grade 0 or 1)
• No frequent knee pain
• No history of:
• Knee surgery (e.g., ACL reconstruction, meniscectomy, patellar realignment)
• Significant knee injury (e.g., ligament tears, fractures, dislocations)
• Diagnosed knee conditions (e.g., patellofemoral pain syndrome, bursitis)

Exclusion Criteria:

• Uncontrolled hypertension or other cardiovascular disease
• A musculoskeletal condition preventing physical testing
• Neurological muscle weakness (e.g., stroke, spinal cord injury)
• BMI >34.9 kg/m²
• Recent hospitalization (past 3 months)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Initial-Exercise'; The initial exercise group will participate in an 8-week eccentric overload exercise intervention using a kBox, with two sessions per week. Participants will then cease the intervention for 8 weeks to enter a detraining period.	Other: Eccentric resistance training; The intervention consists of an eccentric overload resistance training program using a portable flywheel exercise device (kBox). This device generates resistance through inertia, meaning that the load is created by the individual's own movement speed and the effort applied. Participants with knee osteoarthritis will train with the flywheel system for 8 weeks, completing two to three sessions each week, with each session lasting approximately 30 to 45 minutes. The program will focus on functional lower-limb exercises such as squats, step-ups, and knee extensions. These exercises are chosen because they closely mimic everyday movements like climbing and descending stairs. Participants randomized to the delayed-exercise subgroup will continue with usual activity and medical care for the first 8 weeks, serving as a comparison group. After this waiting period, the delayed group will then be offered the same flywheel training protocol.
Experimental: Delayed-Exercise; The 'Delayed-Exercise' group will maintain their normal activity, without intervention, for the first 8 weeks of the study. In the second half of the study, they will begin the same 8-week kBox training completed by the 'Initial-Exercise' group.	Other: Eccentric resistance training; The intervention consists of an eccentric overload resistance training program using a portable flywheel exercise device (kBox). This device generates resistance through inertia, meaning that the load is created by the individual's own movement speed and the effort applied. Participants with knee osteoarthritis will train with the flywheel system for 8 weeks, completing two to three sessions each week, with each session lasting approximately 30 to 45 minutes. The program will focus on functional lower-limb exercises such as squats, step-ups, and knee extensions. These exercises are chosen because they closely mimic everyday movements like climbing and descending stairs. Participants randomized to the delayed-exercise subgroup will continue with usual activity and medical care for the first 8 weeks, serving as a comparison group. After this waiting period, the delayed group will then be offered the same flywheel training protocol.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stair-stepping smoothness	Stair-stepping smoothness quantifies motor coordination during the step-up-and-over test by analyzing the fluidity and consistency of limb movements while ascending and descending stairs. It is calculated using a jerk-based smoothness metric adapted from Gonzales et al., where jerk is defined as the third derivative of the position trajectory with respect to time. The smoothness index is derived by numerically differentiating the position data x(t) obtained from motion capture three times to calculate jerk, then squaring and summing these jerk values over the duration of the movement. Lower values of the smoothness index indicate smoother, more coordinated movements. Differences in this metric will be compared between knee osteoarthritis patients and age-matched healthy controls, with variance explained through linear regression models, and between exercise intervention and delayed exercise subgroups to assess changes in motor control during stair negotiation. Unitless.	Baseline, up to 10 weeks, up to 19 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stepping smoothness symmetry index	Bilateral differences in smoothness during stair-step negotiation (asymmetry between limbs). Unitless.	Baseline, up to 10 weeks, up to 19 weeks
Muscle echogenicity	Muscle echogenicity is measured via diagnostic ultrasound, which quantifies the brightness intensity (greyscale pixel values) of muscle tissue images to provide a non-invasive assessment of muscle composition and quality. Unitless.	Baseline, up to 10 weeks, up to 19 weeks
Muscle thickness	Muscle thickness is a non-invasive ultrasound measure obtained as the distance between superficial and deep muscle borders. Units: mm.	Baseline, up to 10 weeks, up to 19 weeks
Muscle texture analysis (gray-level co-occurrence matrix)	Muscle texture analysis using gray-level co-occurrence matrix (GLCM) is an advanced ultrasound imaging technique that quantitatively assesses the spatial distribution and relationship of pixel intensities within a muscle. Unitless.	Baseline, up to 10 weeks, up to 19 weeks
Grip strength	Grip strength is objectively measured using a handheld dynamometer, recording the maximal isometric force over three trials. Units: kg.	Baseline, up to 10 weeks, up to 19 weeks
Lower limb strength	Lower limb strength assessment are completed using the Biodex system involves isokinetic and isometric dynamometry to quantify maximal voluntary muscle force during knee extension and flexion. Units: Newton-meters.	Baseline, up to 10 weeks, up to 19 weeks
Timed stair ambulation	The Timed Stair Ambulation test measures the time taken for an individual to ascend and descend a flight of stairs, reflecting lower limb muscle power, functional mobility, and endurance. The outcome is the recorded time in seconds to complete the stair climb task, with lower times indicating better physical performance and function. Units: seconds.	Baseline, up to 10 weeks, up to 19 weeks
Short Physical Performance Battery (SPPB)	The Short Physical Performance Battery (SPPB) is an objective assessment tool for evaluating lower extremity physical function using three timed tests: standing balance, 4-meter usual-paced walk, and five repeated chair stands. Each component is scored from 0 to 4 points, yielding a total score range from 0 to 12, where higher scores indicate better physical performance and lower disability.	Baseline, up to 10 weeks, up to 19 weeks
Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)	The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is a patient-reported questionnaire evaluating Osteoarthritis-related pain, stiffness, and physical function with subscale score ranges: Pain (0-20), Stiffness (0-8), and Physical Function (0-68). Higher scores indicate worse symptoms and greater disability. The total score sums all subscales, ranging from 0 to 96, with higher values representing more severe osteoarthritis impact.	Baseline, up to 10 weeks, up to 19 weeks
Joint Position	Linear joint position measured using an optical tracking system during dynamic tasks. Unit of Measure: Meters (m)	Baseline, up to 10 weeks, up to 19 weeks
Joint Linear Velocity	Linear joint velocity derived from optical tracking data during dynamic tasks. Unit of Measure: Meters per second (m/s)	Baseline, up to 10 weeks, up to 19 weeks
Joint Linear Acceleration	Linear joint acceleration derived from optical tracking data during dynamic tasks. Unit of Measure: Meters per second squared (m/s²).	Baseline, up to 10 weeks, up to 19 weeks
Joint Angular Velocity	Angular velocity of the joint measured during dynamic tasks using optical tracking systems. Unit of Measure: Radians per second (rad/s)	Baseline, up to 10 weeks, up to 19 weeks
Joint Angular Acceleration	Angular acceleration of the joint measured during dynamic tasks using optical tracking systems. Unit of Measure: Radians per second squared (rad/s²).	Baseline, up to 10 weeks, up to 19 weeks
Joint Range of Motion	Active joint range of motion measured in the sagittal, frontal, and transverse planes during dynamic tasks using optical tracking systems. Unit of Measure: Degrees (°).	Baseline, up to 10 weeks, up to 19 weeks
Joint Forces	Net joint forces calculated using inverse dynamics during dynamic tasks. These measures reflect the mechanical loads experienced at the joint. Unit of Measure: Newtons (N).	Baseline, up to 10 weeks, up to 19 weeks
Joint Moments (Torques)	Net joint moments calculated using inverse dynamics during dynamic tasks. These measures reflect the rotational loads acting about the joint and provide insight into muscle performance and load distribution. Unit of Measure: Newton-meters (N·m)	Baseline, up to 10 weeks, up to 19 weeks
Self-reported pain	The Visual Analog Scale (VAS) is a unidimensional measure used to assess pain intensity. It consists of a 10-centimeter horizontal line with anchors at each end labeled "no pain" (0) and "worst pain imaginable" (10). Patients mark a point on the line corresponding to their pain level, which is measured in millimeters from the zero end. Higher scores indicate greater pain intensity. This scale provides a continuous range allowing sensitive detection of changes in pain over time.	Baseline, up to 10 weeks, up to 19 weeks

Collaborators and Investigators

• Sponsor: University of Colorado, Denver
• Collaborators: NIH/NCATS Colorado CTSA Grant Number T32TR004367
• Investigators: Principal Investigator: Michael Harris-Love, PT, MPT, DSc, FGSA, FAPTA, University of Colorado, Denver

Study record dates

Study Major Dates

• Study Start (Actual): August 20, 2025
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): May 31, 2029

Study Registration Dates

• First Submitted: October 22, 2025
• First Submitted That Met QC Criteria: February 19, 2026
• First Posted (Actual): February 20, 2026

Study Record Updates

• Last Update Posted (Actual): February 20, 2026
• Last Update Submitted That Met QC Criteria: February 19, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Osteoarthritis
• Other Study ID Numbers: 24-1836; T32TR004367 (U.S. NIH Grant/Contract)

Drug and device information, study documents

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