Is whole body impedance a predictor of blood viscosity?

Article type: Research Article

Authors: Varlet‐Marie, E.^; | Gaudard, A.^; | Mercier, J. | Bressolle, F. | Brun, J.‐F.^;

Affiliations: Laboratoire de Pharmacocinétique Clinique, Faculté de Pharmacie, Université Montpellier I, France | Service Central de Physiologie Clinique, Centre d'Exploration et de Réadaptation des Anomalies du Métabolisme Musculaire (CERAMM), CHU Lapeyronie, Montpellier, France

Note: [] E. V.‐M. and A. G. have equally contributed to this work and should both be considered as first authors.

Note: [] E. V.‐M. and A. G. have equally contributed to this work and should both be considered as first authors.

Note: [] Corresponding author: Dr. J.F. Brun, MD, PhD, Service Central de Physiologie Clinique, Centre d'Exploration et de Réadaptation des Anomalies du Métabolisme Musculaire (CERAMM), CHU Lapeyronie 34295, Montpellier‐cédex 5, France. Tel.: +33 04 67 33 82 84; Fax: +33 04 67 33 59 23; Telex: CHR MONTP 480 766 F; E‐mail: [email protected].

Abstract: Bioelectrical impedancemetry (BIA) has received a widespread interest as a non‐invasive approach to body fluid volumes. Since similar techniques have been studied to assess in vitro rheological properties of blood, we investigated the relationships between whole body impedance and blood viscosity parameters in order to determine possible predictive equations. 30 sportsmen (24.6±1.01 years; 73.96±1.62 kg; 177.73±1.33 cm) were enrolled into the study. Body composition was assessed with a multifrequency bioelectrical impedancemeter (Dietosystem Human IM Scan) using low intensity at the following frequencies: 1, 5, 10, 50 and 100 kHz. Viscometric measurements were done at 1000 s−1 with a falling ball viscometer (MT 90 Medicatest). Hematocrit (Hct) was measured with microcentrifuge. A standardized exercise test was performed on a cycloergometer during 25 minutes. Physical working capacity (W170) was calculated and VO2 max  was evaluated with Astrand nomograms. Two hemorheological parameters were independently correlated with impedance (Z) measurements: whole blood viscosity (WBV) at 100 kHz (r=0.518; p=0.01) and Hct at 1 kHz (r=−0.485; p=0.01). Plasma viscosity was correlated multilinearly with water/fat free mass and Z at 10 kHz (r=0.441; p=0.02). In addition both WBV and Z at 100 kHz exhibited correlations with aerobic working capacity (VO2 max ) with r=−0.482 and r=−0.475 (p≤0.05), respectively. A stepwise regression analysis selects Z at 100 kHz instead of WBV as a predictor of VO2 max . These findings confirm our previous reports about relationships between whole body conductance for high frequency and aerobic working capacity and suggest a new approach for non‐invasive evaluation of blood rheology with BIA.

Keywords: Exercise, impedance, body fluids, blood viscosity, plasma viscosity, hemorheology, aerobic working capacity

Journal: Clinical Hemorheology and Microcirculation, vol. 28, no. 3, pp. 129-137, 2003