LONGITUDINAL-STUDY OF RELATIONSHIPS BETWEEN RED-CELL AGGREGATION AT REST AND LACTATE RESPONSE TO EXERCISE AFTER TRAINING IN YOUNG GYMNASTS

Increased red cell aggregation appears to experimentally impair muscul ar microcirculation and thus O-2 supply to muscles. In sportsmen, we r eported in three different cross-sectional studies a correlation betwe en RBC aggregation and lactate release during exercise, which could be explained by this mechanism. This study aimed at confirming this find ing in a follow up study of young gymnasts submitted to a 6 months tra ining 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 increment al exercise-test on cycloergometer before and after the training sessi on, 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 co rrelated to the difference in blood lactate area under the curve durin g exercise before and after training ('M' index which measures aggrega tion 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 disa ggregation: r=0.832 p<0.01). Changes in plasma viscosity during the sa me period are also positively correlated to changes in lactate area: r =0.717 p<0.02). Since changes in aggregation and changes plasma viscos ity are not correlated, they appear to be independent determinants of lactate response during exercise. Thus, decreases in RBC aggregation a nd/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 agreem ent with previous ones showing a correlation between RBC aggregation a nd lactate response, suggests a possible involvement of RBC aggregatio n in O-2 transfer to exercising muscles.