Measurement of intercostal muscle thickness with ultrasound imaging during maximal breathing.
Ryo Yoshida, Kazuhide Tomita, Kenta Kawamura and 4 others
PMID 31037006WHAT IT FOUND
Ultrasound detected intercostal muscle thickening during maximal breathing only at the front of the chest.
Measurements at the side and back showed no change, meaning this method cannot currently assess respiratory muscle activity across the whole rib cage.
Key findings
01Intercostal muscle thickness significantly increased during maximal breathing in the anterior intercostal spaces.
02No significant differences in muscle thickness were found between rest and maximal breathing in the lateral or posterior portions.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only 12 healthy men, so results may not apply to patients with respiratory conditions or women. Ultrasound could not separate overlapping internal and external intercostal muscles in the lateral and posterior regions, likely causing the null findings in those areas. The study did not validate ultrasound measurements against electromyography (EMG) in the participants, relying on prior literature for that correlation.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that intercostal muscles do not activate during breathing at the side or back of the chest. The lack of ultrasound change in these areas is likely due to the inability to separate overlapping muscle layers, not a lack of muscle activity.