Effect of Inspiratory Muscle Training on Knee Osteoarthritis Pain

NCT07698418 | Not Yet Recruiting

• 1 other identifier: ZHSC-1-(2026)014
• Study Type: interventional
• Target: 80
• Locations: 0 countries
• Sites: N/A

Brief Summary

Knee osteoarthritis (KOA) is a common joint disease that causes chronic pain and limits daily activities. Current treatments, such as painkillers or surgery, have limitations like side effects or high costs. This study will test whether a safe, non-drug intervention-inspiratory muscle training (breathing exercises against resistance)-can reduce knee pain in people with KOA. The training may work by lowering inflammation and improving the brain's modulation of pain. Eighty patients aged ≥55 years with confirmed KOA and frequent knee pain will be enrolled. Participants will be randomly assigned to either an 8-week inspiratory muscle training program (5 sessions per week, with gradually increasing resistance) or a sham (very low resistance) training program. Neither the patients nor the researchers assessing the outcomes will know who is in which group. The main outcome is change in knee pain measured by a visual analog scale (VAS). Secondary outcomes include blood markers of inflammation (TNF-α, IL-6, IL1β), physical function, the Knee injury and Osteoarthritis Outcome Score (KOOS), inspiratory muscle strength, activity level, sleep quality, and quality of life. To explore underlying mechanisms, outcomes included heart rate variability (HRV) as an indicator of autonomic nervous system function, and brain functional connectivity in the prefrontal cortex using functional near-infrared spectroscopy (fNIRS) are collected. These mechanistic assessments will be performed at baseline and at the end of 8-week intervention. Additional follow-up assessments for clinical outcomes will be done at 3 and 6 months after the training ends. Any side effects or adverse events will be recorded. This study will provide high-quality evidence on whether inspiratory muscle training is an effective and safe complementary treatment for knee pain in people with knee OA, and will offer new insights into the mechanisms underlying its analgesic effects.

Conditions

Knee Osteoarthritis; Knee Osteoarthritis (Knee OA)

Keywords

Knee Osteoarthritis; Inspiratory Muscle Training; Chronic Pain

Outcome Measures

Primary Outcomes (1)

• Visual analogue scale

  Self-rated pain intensity of knee (0-100), "0" indicate no pain, "100" indicate worst pain.

  Baseline, week 8, 3-month after intervention, 6-month after intervention

Secondary Outcomes (10)

• The Knee injury and Osteoarthritis Outcome Score

  Baseline, week 8, 3-month after intervention, 6-month after intervention

• Serum levels of inflammatory markers

  Baseline, up to week 8

• Heart rate variability

  Baseline, up to week 8

• Prefrontal cortex activity

  Baseline, up to week 8

• 40-meter walk test

  Baseline, up to week 8

Other Outcomes (2)

• Adherence

  Up to week 8

• Adverse events

  Up to week 8

Study Arms (2)

Inspiratory Muscle Training

EXPERIMENTAL

5 sessions/week for 8 weeks. Load starts at 50% MIP for 40 reps, increases to 80% MIP for 60 reps from week 5, then adjusted weekly to 80% of updated MIP. Device: threshold inspiratory muscle trainer.

Other: Inspiratory muscle training

Sham Inspiratory Muscle Training

SHAM COMPARATOR

Participants perform sham inspiratory muscle training with the same frequency and duration as the experimental group, but the inspiratory load is fixed at 10% of maximal inspiratory pressure (MIP) and does not progress. All other procedures (weekly MIP measurement for sham load adjustment) are identical to maintain blinding.

Other: Sham inspiratory muscle training

Interventions

Inspiratory muscle training OTHER

Participants will perform home-based inspiratory muscle training using a threshold-loading device (POWERbreathe Medic Plus). Training is conducted 5 times per week for 8 weeks. The initial inspiratory load is set at 50% of the individual's maximum inspiratory pressure (MIP), measured weekly at the study site. The load is progressively increased to 80% MIP over the first 4 weeks and maintained at 80% MIP for the remaining 4 weeks. Each session consists of 40-60 breaths. Adherence is monitored via an electronic training log and weekly on-site visits. This protocol is individualized, progressive, and home-based, distinguishing it from fixed-load or supervised-only breathing interventions.

Also known as: Respiratory muscle training

Inspiratory Muscle Training

Sham inspiratory muscle training OTHER

Participants will perform home-based inspiratory muscle training using a threshold-loading device (POWERbreathe Medic Plus). Training is conducted 5 times per week for 8 weeks. The initial inspiratory load is set at 10% of the individual's maximum inspiratory pressure (MIP), measured weekly at the study site. The load is maintained 10% MIP over 8 weeks. Each session consists of 40-60 breaths. Adherence is monitored via an electronic training log and weekly on-site visits.

Sham Inspiratory Muscle Training

Eligibility Criteria

• Age: 55 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Aged 55 years or older.
• Knee osteoarthritis (Kellgren-Lawrence grade ≥ 2).
• Knee pain (Visual Analogue Scale, VAS ≥ 3) on the most days in the past month.
• Able to walk independently without assitive devices.

You may not qualify if:

• History of knee replacement surgery, meniscus surgery, or ligament surgery.
• Received corticosteroid injection within the previous three weeks.
• Diagnosed with rheumatoid arthritis.
• Unstable angina, recent myocardial infarction, uncontrolled cardiac arrhythmia, or severe heart failure.
• History of stroke.
• Currently receiving steroid therapy, hormonal therapy, or cancer chemotherapy.
• Pneumothorax, pulmonary bullae, lung surgery within the past 12 months, unstable asthma, or severe dyspnea at rest.
• Unable to understand the study procedures and potential risks.

Sponsors & Collaborators

• The Hong Kong Polytechnic University: lead
• Zunyi Medical College: collaborator

MeSH Terms

Conditions

Osteoarthritis, Knee; Chronic Pain

Interventions

Breathing Exercises

Condition Hierarchy (Ancestors)

Osteoarthritis; Arthritis; Joint Diseases; Musculoskeletal Diseases; Rheumatic Diseases; Pain; Neurologic Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Mind-Body Therapies; Complementary Therapies; Therapeutics; Exercise Movement Techniques; Physical Therapy Modalities

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: Participants, outcome assessors, and data analyst are blinded. Care provider is not blinded.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Dr.

Model Details: Two parallel arms: experimental (inspiratory muscle training) and control (sham inspiratory muscle training), with a 1:1 allocation ratio.

Study Record Dates

• First Submitted: July 7, 2026
• First Posted: July 13, 2026
• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): September 1, 2030
• Study Completion (Estimated): September 1, 2030
• Last Updated: July 16, 2026

Record last verified: 2026-04