Affiliations: Service d'Exploration Physiologique des Hormones et des Métabolismes, CHU de Montpellier, F-34059 Montpellier, France
Abstract: Increased red cell aggregation appears to experimentally impair muscular microcirculation and thus O2 supply to muscles. In sportsmen, we reported in three different cross-sectional studies a correlation between RBC aggregation and lactate release during exercise, which could be explained by this mechanism. This study aimed at confirming this finding in a follow up study of young gymnasts submitted to a 6 months training session. 11 gymnasts (age 12–14.5 yr; 7 girls and 4 boys; weight 33–60.5 kg; height 1.44–1.7m) underwent a 15 min submaximal incremental exercise-test on cycloergometer before and after the training session, as part of a check-up for detecting adverse effects of training on growth and puberty. The difference between RBC aggregation (measured with the Myrenne erythroaggregometer) before and after training was correlated to the difference in blood lactate area under the curve during exercise before and after training (‘M’ index which measures aggregation during stasis after disaggregation at 600 s−1: r=0.727 p<0.02; ‘M1’ index which measures RBC aggregation at low shear rate after disaggregation: r=0.832 p<0.01). Changes in plasma viscosity during the same period are also positively correlated to changes in lactate area: r=0.717 p<0.02. Since changes in aggregation and changes plasma viscosity are not correlated, they appear to be independent determinants of lactate response during exercise. Thus, decreases in RBC aggregation and/or plasma viscosity after training in young gymnasts are associated with an improvement in aerobic metabolism during exercise. Although a causal relationship remains to be demonstrated, this study, in agreement with previous ones showing a correlation between RBC aggregation and lactate response, suggests a possible involvement of RBC aggregation in O2 transfer to exercising muscles.
