Association between skeletal muscle mass index and lung function/respiratory muscle strength in older adults requiring long-term care or support

[Purpose] We focused on skeletal muscle mass index, one of the biomarkers of sarcopenia, and investigated the association between skeletal muscle mass index and the parameters of lung function and respiratory muscle strength. [Participants and Methods] After applying the exclusion criteria, we included, in this cross-sectional study, 120 community-dwelling older adults aged ≥65 years who required long-term care/support and underwent ambulatory rehabilitation under the long-term care insurance system in Japan. We measured the skeletal muscle mass index, forced vital capacity, forced expiratory volume in 1 second, peak expiratory flow rate, maximum expiratory pressure, and maximum inspiratory pressure. The data were analyzed using Pearson correlation coefficient and multiple regression analysis. [Results] The skeletal muscle mass index was positively correlated with only maximum expiratory pressure for both male and female participants by Pearson’s correlation coefficient. With the skeletal muscle mass index as a dependent variable, only the maximum expiratory pressure was significant for both male and female participants by the multiple regression analysis. [Conclusion] Therefore, the findings of this study suggested that compared with lung function tests, maximum expiratory pressure, which is an indicator of respiratory muscle strength, is related to muscle mass. Maximum expiratory pressure might be the most useful indicator for sarcopenia.