Longitudinal Assessment of Maximal Inspiratory Pressure and Functional Capacity Following Inspiratory Muscle Training in Frail Older Adults: A Randomized, Double-Blind, Sham-Controlled Trial

This study aims to evaluate the effects of an 8-week inspiratory muscle training program on maximal inspiratory pressure and functional capacity in frail older adults aged 80 years and above. Frailty is associated with reduced physical capacity, declines in functional performance, impaired respiratory performance, and a higher risk of disability. Inspiratory muscle training is a simple, low-cost intervention that may improve breathing function, inspiratory muscle strength, and overall health in very old adults, but evidence in this age group remains limited. Participants will be randomly assigned to one of two groups: a high-load inspiratory muscle training group or a low-load sham training group. Both groups will use a threshold device and perform 30 breaths once per day, five days per week, for eight weeks. The experimental group will train with progressively increasing resistance (50% to 80% of maximal inspiratory pressure), while the sham group will use a minimal and non-progressive load (15% of maximal inspiratory pressure). All sessions will be supervised and monitored for safety. The main goal of the study is to determine whether inspiratory muscle training improves maximal inspiratory pressure (MIP), an established measure of global inspiratory muscle strength. Secondary outcomes include measures of functional capacity, reflecting the ability to perform physical tasks relevant to daily living in very old adults. These outcomes will allow the evaluation of the clinical relevance of improvements in inspiratory muscle strength in this population. Assessments will be performed before the intervention, immediately after the 8-week program, and again at one and three months after the end of the intervention to examine both immediate and short-term effects. This study may contribute valuable evidence regarding the safety, feasibility, and clinical benefits of inspiratory muscle training in frail very old adults, particularly its impact on inspiratory muscle strength and functional capacity, supporting its potential implementation in rehabilitation and geriatric care.