Influence of an Inspiratory Muscle Fatigue Protocol on Older Adults on Respiratory Muscle Strength, Muscle Oxygen Saturation, and Functional Capacity. A randomized controlled trial

Abstract

Background The fatigue of the inspiratory musculature, particularly the diaphragm, has been demonstrated to exert systemic effects on the body, impacting cardiovascular and performance outcomes. This study aimed to evaluate the influence of an inspiratory muscle fatigue protocol on respiratory muscle strength, functionality, and muscle oxygen saturation in older adults. Methods A double-blinded randomized controlled clinical trial was conducted on twenty-four older adults aged over 60 years, who were physically independent in terms of gait and transfers. Participants were randomly assigned to one of three groups: control, inspiratory muscle fatigue, or activation. Diaphragmatic ultrasonography, maximum inspiratory pressure, muscle oxygen saturation, and functionality were assessed at two time points: before intervention (T1) and immediately post-treatment (T2). Results The inspiratory muscle fatigue group showed lower scores for respiratory and functional variables after performing the diaphragmatic fatigue intervention than the activation and control group (p < 0.05), on the other hand, the activation group showed more positive values for functional and respiratory capacity variables after performing the inspiratory muscle activation training (p< 0.05). Conclusions Fatigue of the inspiratory musculature appears to negatively impact inspiratory muscle strength, peripheral muscle strength, muscular oxygenation, and functionality in older adults. Trial registration: ClinicalTrials.gov ID: NCT06266013.