title: Contribution of systemic arterial compliance and systemic vascular resistance to effective arterial elastance changes during exercise in humans.
abstract: BACKGROUND
  Effective arterial elastance (Ea), an index of arterial load, increases with elevations in left ventricular elastance to maximize the efficiency of left ventricular stroke work during exercise. Systemic arterial compliance (C) and vascular resistance (R) are the primary components contributing to Ea, and R plays a greater role in determining Ea at rest. We hypothesized that the contribution of C to Ea increases during exercise to maintain an optimal balance between arterial load and ventricular elastance, and that the increase in Ea is due primarily to a reduction in C.
  
  
  OBJECTIVE
  The aim of this study was to investigate the contributions of C and R to Ea during exercise.
  
  
  METHODS
  Ea (0.9 x systolic blood pressure/stroke volume), C (stroke volume/pulse pressure), R (mean blood pressure/cardiac output), and cardiac cycle length (T) were measured at rest and during exercise of 40%, 60% and 80% maximal oxygen uptake (O(2max)) using Doppler echocardiography in 45 healthy men.
  
  
  RESULTS
  Ea did not differ between rest and 40%O(2max), but it was greater at 60% and 80%O(2max). C markedly decreased during exercise in an exercise intensity-dependent manner. The changes in R/T during exercise were small, whereas it decreased at 40%O(2max) and gradually increased at 60% and 80%O(2max).
  
  
  CONCLUSIONS
  The present results suggest that the contribution of systemic arterial compliance to effective arterial elastance increases during exercise. Therefore, we propose that the increase in arterial load during exercise is mainly driven by a reduction in systemic arterial compliance.
authors.affiliation: Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Otsuki
authors.forename: S
authors.initials: S
authors.lastname: Maeda
authors.forename: M
authors.initials: M
authors.lastname: Iemitsu
authors.forename: Y
authors.initials: Y
authors.lastname: Saito
authors.forename: Y
authors.initials: Y
authors.lastname: Tanimura
authors.forename: R
authors.initials: R
authors.lastname: Ajisaka
authors.forename: T
authors.initials: T
authors.lastname: Miyauchi
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output; D003187:Compliance; D015150:Echocardiography, Doppler; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D010100:Oxygen / Q000378:metabolism; D013318:Stroke Volume; D014655:Vascular Resistance; D014664:Vasodilation / Q000502:physiology*
chemical_list: D010100:Oxygen