Affiliations: Service d'Exploration Physiologique des Hormones et des Métabolismes, CHRU Lapeyronie 34059 Montpellier-cédex, France | INSERM U103 (Biomechanics), Montpellier, France
Abstract: The effect of breakfast on blood rheology during exercise was studied. 5 subjects (23–27 yr weight 60–84 kg, height 1,72–1,84 m) performed in random order two 25 min submaximal exercise sessions including a final step at 85% of theoretical maximal heart rate during 15 min. This was done fasting and again after eating a 495 kcal breakfast (8,9% proteins, 27,3% lipids; 63.9% glucids). The rheologic response to exercise was measured at high shear rate with the MT90 viscometer. Changes in whole blood viscosity and hematocrit were similar, but fasting subjects underwent an increase in RBC rigidify (Tk index) while plasma viscosity was higher after breakfast and exhibited a stronger increase during cycling. This breakfast modifies the rheologic response to exercise, by preventing a reduction in RBC deformability and increasing plasma viscosity as well as its rise during cycling.
