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. 2020 Jul 13;15:1697–1711. doi: 10.2147/COPD.S260735

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© 2020 Yamamoto et al.

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Results of univariate analyses and Spearman’s rank correlation coefficient analyses between inspiratory resonant frequency (Fres-ins) at rest and ventilatory parameters of cardiopulmonary exercise testing (CPET) (n=55). In each figure, the graphs on the left show the results of Fres-ins at rest and CPET ventilatory parameters at peak exercise, while those on the right show the results of Fres-ins at rest and ventilatory parameters at rest, respectively. (A) Fres-ins and expiratory tidal volume (V_T ex). (B) Fres-ins and mean expiratory flow (V_T ex/Te). (C) Fres-ins and breathing frequency (f_R). (D) Fres-ins and minute ventilation (V’_E). (E) Fres-ins and oxygen uptake (V’_O2). *p<0.05; **p<0.01.

Abbreviations: CPET, cardiopulmonary exercise testing; f_R, breathing frequency; Fres-ins, inspiratory resonant frequency; NS, not significant; R², R-squared; r_S, Spearman’s rank correlation coefficient; std β, standardized regression coefficient estimate; V’_E, minute ventilation; V’_O2, oxygen uptake; V_T ex, expiratory tidal volume; V_T ex/Te, mean expiratory flow.