title: Role of heart rate and stroke volume during muscle metaboreflex-induced cardiac output increase: differences between activation during and after exercise.
abstract: We hypothesized that the role of stroke volume (SV) in the metaboreflex-induced cardiac output (CO) increase was blunted when the metaboreflex was stimulated by exercise muscle ischemia (EMI) compared with post-exercise muscle ischemia (PEMI), because during EMI heart rate (HR) increases and limits diastolic filling. Twelve healthy volunteers were recruited and their hemodynamic responses to the metaboreflex evoked by EMI, PEMI, and by a control dynamic exercise were assessed. The main finding was that the blood pressure increment was very similar in the EMI and PEMI settings. In both conditions the main mechanism used to raise blood pressure was a CO elevation. However, during the EMI test CO was increased as a result of HR elevation whereas during the PEMI test CO was increased as a result of an increase in SV. These results were explainable on the basis of the different HR behavior between the two settings, which in turn led to different diastolic time and myocardial performance.
authors.affiliation: Section of Human Physiology, Department of Science Applied to Biological Systems, University of Cagliari, Via Porcell 4, 09124 Cagliari, Italy. crisafulli@tiscali.it
authors.forename: Antonio
authors.initials: A
authors.lastname: Crisafulli
authors.forename: Francesco
authors.initials: F
authors.lastname: Piras
authors.forename: Michele
authors.initials: M
authors.lastname: Filippi
authors.forename: Carlo
authors.initials: C
authors.lastname: Piredda
authors.forename: Paolo
authors.initials: P
authors.lastname: Chiappori
authors.forename: Franco
authors.initials: F
authors.lastname: Melis
authors.forename: Raffaele
authors.initials: R
authors.lastname: Milia
authors.forename: Filippo
authors.initials: F
authors.lastname: Tocco
authors.forename: Alberto
authors.initials: A
authors.lastname: Concu
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D012018:Reflex / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology*