Determinants of dynamic inspiratory muscle strength in healthy trained elderly

ABSTRACT

Background

The S-Index assessed by means of electronic devices is a measure of Inspiratory Muscle Strength (IMS) that highly correlates with the maximal inspiratory pressure (MIP). The variables involved when using regression models for the prediction of IMS/MIP depend on both the sample characteristics and the device or protocol used. In light of the scarce information on the influence of physical activity (PA) on IMS in healthy older adults (OA), together with the incorporation of new assessment devices, the objectives of this research are: 1) to determine which factors influence the IMS in a group of trained OA, using a portable electronic device; and 2) to propose a regression model to improve its assessment and training.

Methods

One hundred and fifty-nine individuals were assessed for body composition, lung capacity, IMS, and PA. A total of 92 individuals (72.73 ± 4.99 years) were considered for the final sample.

Results

Using age, sex, and weight as control variables, forced expiratory volume in the first second (FEV₁) is the variable which is most likely to be included in the model (80%), without physical fitness appearing to be decisive. In the absence of spirometric variables, cardiorespiratory fitness (6MWT) takes on this role in a predictive model (16%).

Conclusions

This is the first study proposing IMS predictive formulas considering spirometry and/or physical fitness results for a Spanish, healthy, and trained OAs population. A predictive formula including also the spirometric variables (mainly the FEV₁) might better predict the inspiratory muscle strength. In addition, physical and respiratory functions confirm to be different, so it is necessary for the inspiratory muscles to be trained in a specific way.

KEYWORDS:

• Respiratory training
• functional assessment
• predictive equations
• inspiratory muscle strength
• clinical assessment
• normal values

Transparency

Declaration of funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors

Declaration of financial/other interests: The contents of the paper and the opinions expressed within are those of the authors, and it was the decision of the authors to submit the manuscript for publication. The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Peer reviewers in this manuscript have no relevant financial or other relationships to disclose.

Acknowledgments

The authors want to thank the University of Valencia for its support, as well as those elderly in the association EcM, always willing to help. AF wants to thank the support of the research grant PID2019-104790GB-I00 from the Spanish Ministry of Science and Innovation.

Data sharing

The data that support the findings of this study are available from the corresponding author, AF, upon reasonable request.

Declaration of interest

No potential conflict of interest was reported by the author(s).