Investigation of the relationship between respiratory muscle strength, respiratory muscle endurance and trunk muscle endurance

Objective: In healthy individuals; To examine the relationship between trunk muscle endurance, respiratory muscle strength and respiratory muscle endurance. Method: A total of 51 healthy participants aged between 18 and 35 years were included in the study. Demographic and clinical information of the participants were recorded. Pulmonary function tests (PFT) were evaluated with spirometry, respiratory muscle strengths with intraoral pressure measurement (MIP and MEP), respiratory muscle endurance with increased threshold load endurance test, and trunk muscle endurance with McGill trunk endurance tests. A stepwise linear regression analysis was applied for determinants of contributions of trunk endurance. Results: The mean age and body mass index (BMI) of the participants were 21.8 ± 3.2, 22.0 ± 3.9, respectively. A strong positive correlation was found between the respiratory muscle endurance and the scores of the flexor endurance test (r = 0.556) and the side bridge test (r = 0.623) (p <0.05). In addition, a positive moderate correlation was found between respiratory muscle strength and the scores of the Flexor endurance test (r = 0.473) and the Side bridge test (r = 0.493) (p <0.05). The best significant model for the Side bridge test score consisted of respiratory endurance and respiratory muscle strength (Model: Adj R2 = 0.46, F = 21.40, p <0.001). The best significant model for the flexor endurance test score was composed of respiratory endurance and respiratory muscle strength (Model: Adj R2 = 0.38, F = 15.65, p <0.001). Conclusion: Respiratory muscle strength and respiratory muscle endurance are independent determinants of trunk muscle endurance in healthy individuals. However, respiratory muscle endurance affects more than respiratory muscle strength. In conclusion, we think that it may be beneficial to include respiratory muscle endurance training as well as respiratory muscle strength training in trunk muscle training programs.