The goal of this clinical trial is to determine the effects of a 12-week respiratory muscle training (RMT) intervention on cardiopulmonary function and compare its efficacy with aerobic exercise in older adults. The main questions it aims to answer are:

• What are the effects of RMT compared to aerobic exercise on cardiopulmonary function?
• What is the minimal effective duration (temporal threshold) for observable physiological adaptations to RMT?
• To what extent are the training effects retained at 4-weeks post-intervention? Participants were randomly divided into RMT group and aerobic exercise group. The RMT group performed 12 weeks of progressive resistance training (initial, moderate, and high levels) using the Lung Fitness® breathing trainer, consisting of 10 breaths per set, 3 sets per session, twice daily (morning and evening), 5 days per week. The Aerobic Exercise group performed daily 10,000-step walking sessions 5 days per week, with exercise adherence assessed using the Exercise Adherence Questionnaire.

30 subjects were finally included through the screening criteria. The names of all subjects were entered into Microsoft Excel 2016 and the RAND function was used to generate a random number between 0 and 1 for each subject, each random number being different. Subjects with an odd number of random numbers were assigned to the respiratory muscle training (RMT) group and those with an even number of random numbers were assigned to the aerobic exercise group. The final two intervention groups of 30 participants, were assigned and baseline testing was performed. Testing was repeated at five standardized time points (baseline, week 4, week 8, week 12 [post-intervention], and week 16 [post-detraining]).

The technical route of this study was to collect basic information about the study subjects, including age, height, weight, and to test the inspiratory muscle function, pulmonary function and the 6MWT of the study subjects. The RMT group performed 12 weeks of progressive resistance training (initial, moderate, and high levels) using the Lung Fitness® breathing trainer, consisting of 10 breaths per set, 3 sets per session, twice daily (morning and evening), 5 days per week. The aerobic exercise group performed daily 10,000-step walking sessions 5 days per week, with exercise adherence assessed using the Exercise Adherence Questionnaire.

Basic information and experimental data entry and organization were performed using Microsoft Excel 2016, and the results of all indicators measured before and after the experiment were analyzed and calculated in International Business Machines (IBM) SPSS Statistics 26.0. The data were tested for normality using the Shapiro-Wilk Test (Shapiro-Wilk Test). For the series conforming to the normal distribution, expressed as mean (Mean) and standard deviation (SD). Variables derived from inspiratory muscle function tests, pulmonary function tests, and 6MWT were analyzed for intergroup differences using paired-samples t-tests. Within-group comparisons across different time points in the RMT group were assessed via one-way repeated-measures analysis of variance (ANOVA) with Bonferroni post hoc correction. RPB and RPE were analyzed using nonparametric tests (Wilcoxon signed-rank test). Statistical significance was set at p < .05 (two-tailed). All data were tested for normality using the Shapiro-Wilk test prior to analysis.

Inclusion Criteria:

• Older adults aged 60-75 years; Regardless of sex; Individuals classified as either physically inactive or habitual exercisers;

Exclusion Criteria:

• Individuals with cardiorespiratory diseases, hypertension, metabolic disorders, or other underlying medical conditions; Persons with impaired mobility, exercise contraindications, or inability to complete the exercise protocol; Inability to independently complete a Six-Minute Walk Test (6MWT) distance.