Association between skeletal muscle mass index and lung function/respiratory muscle strength in older adults requiring long-term care or support.
Yohei Sawaya, Masahiro Ishizaka, Akira Kubo and 5 others
PMID 33281292WHAT IT FOUND
In 120 older adults needing long-term care, higher skeletal muscle mass was related to stronger maximum expiratory pressure, not peak flow.
This links body muscle mass to breathing muscle strength, but does not prove cause.
Key findings
01Skeletal muscle mass index was positively correlated with maximum expiratory pressure (PE max) in men (r=0.344) and women (r=0.393).
02In multiple regression, PE max was the only significant breathing measure related to SMI in men (β=0.396) and women (β=0.375).
03Peak expiratory flow rate was not significantly related to SMI in men (r=0.217) or women (r=0.248).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
This was a cross-sectional association study, so it cannot show that low skeletal muscle mass causes weaker breathing or that increasing muscle mass improves respiratory pressure. The study used SMI alone as a sarcopenia biomarker, not a full sarcopenia diagnosis based on strength and physical function. Many potential participants were excluded; 30 could not stand for muscle mass measurement, so results apply to older adults who could stand and complete all tests. Participants had varied diagnoses, and disease-related factors could not be separated from the observed associations.
Declared interests
No funding was reported, and the author declared no conflict of interest.
The easy way to misread this
Do not read this as evidence that sarcopenia causes weak breathing or that muscle training will improve respiratory muscle strength. The study only measured an association in 120 older adults who could stand and complete breathing tests, and several other breathing measures were not related to muscle mass.