A Simplified And Reproducible Tool For Assessing Inspiratory Muscle Force Perception In Healthy Adults Using Magnitude Production Tasks

The ability to precisely assess the perception of inspiratory muscle force is important, given that the sensory quality of physical breathing effort is a significant contributor to the perception of breathlessness. However, the existing methods for assessing inspiratory muscle force are often complex, may not be easily accessible in clinical settings, and their test-retest reproducibility remains unknown. PURPOSE: To evaluate the utility and reproducibility of a simplified tool for assessing inspiratory force perception in healthy adults using the psychophysical technique of magnitude production (MP) with the modified Borg Category-Ratio (CR10) scale. METHODS: Fifteen healthy adults (mean age ± SD = 23.1 ± 4.5 years) produced static inspiratory muscle forces across seven effort levels (0.5, 1, 2, 3, 5, 7, 10) based on the CR10 scale. Each level was repeated in 5 blocks within a single visit while the average mouth pressure across the final one-second of each effort and the minimum (peak) mouth pressure of each effort were recorded. Maximal inspiratory pressure (MIP) was measured before and after the MP tasks. Following each effort, participants rated their perceived accuracy using a 5-point Likert scale. RESULTS: Participants were generally able to produce distinct pressure levels as requested in the MP tasks, requiring only two to three trials to obtain a representative mean mouth pressure for most levels. Although minor respiratory muscle fatigue occurred (Δ7.7 ± 41.4 cmH2O, P < 0.05), the psychophysical properties of inspiratory muscle force were preserved without significantly impacting cardiovascular parameters. CONCLUSIONS: This simplified, reproducible tool offers an accessible option for assessing inspiratory force perception in both research and clinical settings. Its ease of use, affordability, and portability make it ideal for diverse environments, including resource-limited settings, thus expanding access to effective assessment of physical breathing effort.