Characteristics of respiratory muscle fatigue upon inhalation resistance with a maximal inspiratory mouth pressure of 50.
Toshiya Tsukamoto, Hitoshi Maruyama, Michitaka Kato and 2 others
PMID 31037002WHAT IT FOUND
In 14 healthy men, breathing against a 50% inspiratory load for 20 minutes lowered inspiratory and expiratory mouth pressure.
Pressure changed significantly during 30 minutes of rest. The neck and abdominal muscles showed the clearest fatigue.
Key findings
01Under the inspiratory load, PImax differed significantly from pre-load at 14 and 20 minutes, and PEmax differed significantly from pre-load at 14, 18, and 20 minutes; the 20-minute values were lower than pre-load.
02During rest, PImax differed significantly from the 20-minute load value from 15 to 30 minutes, and PEmax differed significantly at 30 minutes.
03EMG median power frequency differed significantly from pre-load at 20 minutes of load in the sternocleidomastoid during PImax testing and in the rectus abdominis during PEmax testing.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Fourteen healthy adult male volunteers only, so the findings do not apply to women, older adults, or people with breathing disease. The study did not measure lung capacity. It did not test respiratory muscle fatigue in people with COPD or chronic respiratory disease. It tested an experimental inspiratory load, not a training programme or clinical outcome. The no-load comparison was done on a different day within four weeks.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not read this as evidence that inspiratory muscle training improves patients with COPD or respiratory disease. It tested 14 healthy adult men in a lab load, not a treatment, and did not measure patient outcomes. The 30-minute recovery finding was measured after an experimental load in healthy men, not in patients.