Accurate assessment of respiratory muscle strength is crucial for diagnosing and managing respiratory diseases. However, existing reference values may not be generalizable across diverse populations. This study aimed to establish predicted values for maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and sniff nasal inspiratory pressure (SNIP) in Southeast Asian adults.

: MIP, MEP, and SNIP were measured in 301 healthy Vietnamese adults. Two-way ANOVA and post-hoc tests were used to examine differences in these measures among age groups and between genders. Stepwise multiple linear regression was used to develop predictive equations for MIP, MEP, and SNIP, with potential predictors including age, gender, body mass index, and lung function. The lower limit of the normal range was determined using the fifth percentile of the negative residuals.

: MIP, MEP, and SNIP were higher in males than in females. MIP and MEP declined with age, while SNIP remained relatively stable. Predictive equations were established: MIP = 95.2 – 32.1 x gender (male = 0, female = 1) – 0.41 x age + 1.2 x BMI (adjusted R²: 41%, LLN = predicted MIP – 34), MEP = 135.1 – 46.75 x gender (male = 0, female = 1) - 0.6 x age + 1.34 x BMI (adjusted R²: 41.8%, LLN = predicted MEP – 50), SNIP = 63.8 – 18.16 x gender (male = 0, female = 1) (adjusted R²: 14.8%, LLN = predicted SNIP – 30).

: This study provides ethnic-specific predictive equations for MIP, MEP, and SNIP, which may serve as a preliminary step toward developing reference values for the Southeast Asian region.