Exercise-induced plasma volume expansion and post-exercise parasympathetic reactivation
Computing, Health and Science
Exercise, Biomedical and Health Science, Centre for Exercise and Sports Science Research
The purpose of this study was to investigate the effect of exercise-induced plasma volume expansion on post-exercise parasympathetic reactivation. Before (D0) 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 D0 to D+2. Parasympathetic reactivation was evaluated through HRR and vagal-related indexes calculated during a stationary period of recovery. Compared with D0, ∆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.