PTOTCohortJournal of physical therapy science2025

Correlation between respiratory muscle strength and arm muscle strength of the unaffected side in patients with sub-acute stroke.

Daiki Mizubata, Motoyuki Abe, Naohiro Ozeki

PMID 40599835

WHAT IT FOUND

In stroke patients who could not walk alone, respiratory strength and arm strength on the unaffected side were both far below healthy levels.

Over two months of standard rehab, these improved but did not reach normal. The two strengths tracked together closely.

Key findings

01At admission, respiratory muscle strength (MIP and MEP) and arm strength on the unaffected side (shoulder flexion and handgrip) were all significantly lower in stroke patients than in age- and sex-matched healthy controls.

02Over two months of conventional rehabilitation, MIP, MEP, and arm strength on both sides increased significantly, but the values did not reach the levels seen in healthy controls.

03Respiratory muscle strength was positively correlated with proximal and distal arm muscle strength on the unaffected side at all time points, but not with arm strength on the affected side or with functional independence scores.

STILL TO COME

How it was doneWhat they foundWhat it means for PTsWhat it means for OTs

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What it does not show

The sample size was very small (20 patients), which limits the reliability of the findings and prevented subgroup analysis by age, sex, or severity of paralysis. The patients were selected for severe impairment (excluded if they could walk), so the results may not apply to stroke patients who are more mobile. The study was observational and cross-sectional in its comparison with controls, so it cannot prove that respiratory weakness causes arm weakness or vice versa. Healthy controls were measured only once, while stroke patients were measured over time, which introduces potential bias in how the groups are compared.

Declared interests

The authors declared no conflicts of interest, and the study received no external funding.

The easy way to misread this

Do not assume that improving respiratory muscle strength will directly improve functional independence or arm strength on the affected side. The study found no significant correlation between respiratory strength and mFIM scores or affected-side arm strength, and it cannot establish a causal link between respiratory and arm weakness.

Read it on PubMed →