title: Exercise-induced plasma volume expansion and post-exercise parasympathetic reactivation.
abstract: The purpose of this study was to investigate the effect of exercise-induced plasma volume expansion on post-exercise parasympathetic reactivation. Before (D(0)) and 2 days after (D(+2)) a supramaximal exercise session, 11 men (21.4 +/- 2.6 years and BMI = 23.0 +/- 1.4) performed 6-min of submaximal running where heart rate (HR) recovery (HRR) and HR variability (HRV) indices were calculated during the first 10 min of recovery. Relative plasma volume changes (PV) were calculated using changes in hematocrit and hemoglobin measured over consecutive mornings from D(0) to D(+2). Parasympathetic reactivation was evaluated through HRR and vagal-related indexes calculated during a stationary period of recovery. Compared with D(0), PV (+4.8%, P < 0.01) and all vagal-related HRV indices were significantly higher at D(+2) (all P < 0.05). HRR was not different between trials. Changes in HRV indices, but not HRR, were related to PV (all P < 0.01). HRR and HRV indices characterize distinct independent aspects of cardiac parasympathetic function, with HRV indices being more sensitive to changes in plasma volume than HRR.
authors.affiliation: Faculty of Sport Sciences, Research Laboratory, EA 3300 Laboratory of Exercise Physiology and Rehabilitation, University of Picardie, Jules Verne, Amiens, France. martin.buchheit@u-picardie.fr
authors.forename: M
authors.initials: M
authors.lastname: Buchheit
authors.forename: P B
authors.initials: PB
authors.lastname: Laursen
authors.forename: H
authors.initials: H
authors.lastname: Al Haddad
authors.forename: S
authors.initials: S
authors.lastname: Ahmaidi
mesh_terms: D004909:Erythrocyte Indices / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance; D006339:Heart Rate / Q000502:physiology*; D006400:Hematocrit; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D008297:Male; D010275:Parasympathetic Nervous System / Q000502:physiology; D010953:Plasma Volume / Q000502:physiology*; D012420:Running / Q000502:physiology; D055815:Young Adult