Effect of Inspiratory Muscle Training on Knee Osteoarthritis Pain

Conditions

• Knee Osteoarthritis
• Knee Osteoarthritis (Knee OA)

Eligibility Criteria

Sex

ALL

Age

55 Years - 80 Years

Healthy Volunteers

Not accepted

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.
• 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.

Study Details

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.

Key Dates

First listed

Jul 13, 2026

Start date

Sep 1, 2026

Status verified

Apr 2026

Primary completion

Sep 1, 2030

Completion

Sep 1, 2030

Study Design

Enrollment

80 participants (estimated)

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

TREATMENT

Arms

• Experimental: Inspiratory Muscle Training
  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.
• Sham Comparator: Sham Inspiratory Muscle Training
  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.

Primary Outcome Measure

Visual analogue scale [ Time Frame: Baseline, week 8, 3-month after intervention, 6-month after intervention ]

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