Abstract

Acute aerobic exercise leads to: fluid shift from intra- to extra-vascular compartment, redistribution of regional and organ blood volume and fluid loss due to thermoregulation. In this study, we have verified if bioelectrical impedance analysis (BIA) may be useful to monitor fluid shift during aerobic exercise. This method allows measurement of resistance (R), inversely proportional to total body water and reactance (Xc), expression of capacitance produced by cell membranes. While many works have validated the use of BIA for the estimation of total body water in normo-hydrated subjects, there are few works on the use of BIA when a rapid redistribution of extracellular fluid occurs. Ten healthy volunteers, 5 males and 5 females, performed a maximal aerobic exercise on a cycle ergometer. Body weight decreased (males: p 0.01, females: p 0.009) and hematocrit increased (males: p 0.003, females: p 0.02) after exercise. Mean impedance vector showed no significative changes. Therefore, BIA does not seem to be useful for monitoring fluid shift during acute aerobic stress, probably because fluids remain within extra-cellular compartment, or because this method is not sensitive enough, or for disturbance of BIA's measures by cutaneous blood flow changes. Verf.-Referat