Evaluation of the 40 Mmhg Endurance Test as a Measure of Expiratory Muscle Function: A Cross-Sectional Study in Young Adults

Abstract

Background: The 40 mm Hg endurance test is a simple, non-invasive measure of expiratory muscle endurance that requires subjects to sustain expiratory pressure against a sphygmomanometer. Despite its utility, limited research has correlated this test with standard spirometric parameters in Indian populations.

Objective: To analyze the correlation between 40 mm Hg endurance test performance and respiratory function parameters including vital capacity, maximum expiratory pressure, maximum breathing capacity, and breath holding time and evaluate it (40 mm endurance test) as a measure of Expiratory Muscle Function.

Methods: Cross-sectional analysis of respiratory function data from 236 young adults (95 males, 141 females) aged 18-25 years from Surat, Gujarat. Participants underwent spirometric assessment and the 40 mm Hg endurance test. Pearson correlation coefficients were calculated between endurance scores and respiratory parameters.

Results: Mean 40 mm endurance was 41.90 ± 12.01 seconds in males and 48.05 ± 12.37 seconds in females. Strong positive correlation was found between 40 mm endurance and maximum expiratory pressure (r = 0.888, p < 0.0001), and moderate correlation with maximum breathing capacity (r = 0.367, p < 0.0001). No significant correlations were observed with vital capacity, breath holding time, height, or weight.

Conclusion: The 40 mm Hg endurance test demonstrates strong correlation with maximum expiratory pressure, validating its utility as a measure of expiratory muscle strength and endurance. These findings align with previous respiratory muscle training studies and support the use of this simple test in clinical and research settings.