Effect of Inspiratory Muscle Training on Knee Osteoarthritis Pain

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)

Interventions

OTHER

Inspiratory muscle training

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.

OTHER

Sham inspiratory muscle training

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.

Sponsors & Collaborators

• Zunyi Medical College

  collaborator OTHER

• The Hong Kong Polytechnic University

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Model

PARALLEL

Eligibility

Min Age

55 Years

Max Age

80 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2026-09-01

Primary Completion

2030-09-01

Completion

2030-09-01