biostudies-literatureWang YPMinistry of Science and Technology, TaiwanNational Yang Ming Chiao Tung UniversityBrain Research Center, National Yang-Ming University2101-2110https://www.ebi.ac.uk/biostudies/studies/S-EPMC11199285biostudies-literatureUnknown124(7)<h4>Purpose</h4>Low values of heart rate deceleration capacity (DC) and heart rate asymmetry (HRA) are associated with cardiovascular risks. Slow respiration has been proven to enhance the magnitudes of these indexes, but individual inspiratory (T_I) and expiratory (T_E) durations were not controlled in most studies. This study aims to examine whether the effects of T_I and T_E on these indexes would be the same and, if not, how to adjust T_I and T_E to maximize the effect of slow respiration.<h4>Methods</h4>We evaluated 14 seated healthy young adults who randomly controlled their breathing to nine combinations of T_I and T_E, each chosen respectively from 2, 4, and 6 s. A 5-min R-R interval time series was obtEuropean journal of applied physiologyDifferent effects of inspiratory duration and expiratory duration on heart rate deceleration capacity and heart rate asymmetry.PMC11199285MOST 110-2629-B-A49A-501112W32101Wang GZWang YPKuo TBJYang CCHfalseDifferent effects of inspiratory duration and expiratory duration on heart rate deceleration capacity and heart rate asymmetry.<h4>Purpose</h4>Low values of heart rate deceleration capacity (DC) and heart rate asymmetry (HRA) are associated with cardiovascular risks. Slow respiration has been proven to enhance the magnitudes of these indexes, but individual inspiratory (T_I) and expiratory (T_E) durations were not controlled in most studies. This study aims to examine whether the effects of T_I and T_E on these indexes would be the same and, if not, how to adjust T_I and T_E to maximize the effect of slow respiration.<h4>Methods</h4>We evaluated 14 seated healthy young adults who randomly controlled their breathing to nine combinations of T_I and T_E, each chosen respectively from 2, 4, and 6 s. A 5-min R-R interval time series was obt2024-01-01T00:00:00Z2024 Jul2025-04-26T22:36:30.783Z2025-04-06T17:19:15.883ZS-EPMC111992853842142810.1007/s00421-024-05433-2