Effect of inspiratory muscle training on inspiratory muscle strength in adults with post-COVID-19 condition and inspiratory muscle weakness: a randomized controlled trial

Clinical Snapshot

Key Findings

• P Value: Not explicitly stated but CI excludes null

• Effect Size: Mean difference 18% favouring intervention group

• Primary Outcome: 18% improvement in inspiratory muscle strength (Maximal Inspiratory Pressure)

• Nnt Or Sensitivity: OR for clinically meaningful improvement: 7.08 (95% CI: 1.31-38.32)

• Confidence Interval: 95% CI: 5-30%

Clinical Application

Requires specialized respiratory physiotherapy expertise and equipment for maximal inspiratory pressure measurement and training devices Relevant for Australian post-COVID rehabilitation services. May align with RACGP post-COVID management guidelines. Physiotherapy services potentially covered under Medicare chronic disease management plans or private health insurance Adults with post-COVID-19 condition experiencing inspiratory muscle weakness, particularly those with mild to moderate severity

Abstract

OBJECTIVE: Evaluate the effect of inspiratory muscle training in adults with post-COVID-19 condition (PCC) and inspiratory muscle weakness. DESIGN: Randomized controlled trial. SUBJECTS/PATIENTS: Adults with PCC and inspiratory muscle weakness. METHODS: Participants were randomized to inspiratory muscle training twice daily plus individualized exercise twice weekly or exercise alone, with weekly follow-ups over 8 weeks. PRIMARY OUTCOME: inspiratory muscle strength (Maximal Inspiratory Pressure). SECONDARY OUTCOMES: expiratory muscle strength (Maximal Expiratory Pressure); functional capacity (Six‑Minute Walk Test; One‑Minute Sit‑to‑Stand); lung function (spirometry); dyspnoea (mMRC); respiratory symptoms (chest tightness, impaired deep breathing, breathing‑related pain); cough frequency (CAAT cough item); fatigue (Fatigue Severity Scale); physical activity (Frändin-Grimby Activity Scale); activity limitations (Patient‑Specific Functional Scale); and health-related quality of life (EQ‑5D‑5L). Intention-to-treat analyses used imputed missing data. Estimated sample size: 90. RESULTS: Forty-four participants were included (median age 47; 82% women; n = 22/group). Between‑group differences favoured the intervention for inspiratory muscle strength (mean difference: 18%; 95% CI: 5-30; OR for clinically meaningful improvement: 7.08, 95% CI: 1.31-38.32) and cough frequency. No other between-group differences were observed. CONCLUSION: Inspiratory muscle training may improve inspiratory muscle strength and reduce cough frequency, but limited sample size and underrepresentation of the most severely affected warrant cautious interpretation.

References

1. 1.Törnberg, A., Svensson-Raskh, A., Rydwik, E., Halvarsson, A., Bruchfeld, J., & Nygren-Bonnier, M. (2026). Effect of inspiratory muscle training on inspiratory muscle strength in adults with post-COVID-19 condition and inspiratory muscle weakness: a randomized controlled trial. Journal of Rehabilitation Medicine, 58, 44931. https://doi.org/10.2340/jrm.v58.44931