RESPONSES OF BLOOD AND PLASMA LACTATE AND PLASMA PURINE CONCENTRATIONS TO MAXIMAL EXERCISE AND THEIR RELATION TO PERFORMANCE IN STANDARD-BRED TROTTERS

Objective-To study whether end products of 2 pathways of anaerobic ene rgy metabolism, lactate and purines, that accumulate in the blood afte r intense exercise indicate any relation to exercise performance. Desi gn-Venous blood samples were taken within 1 and 15 minutes after a tro tting race of 2,100 m. Animals-16 Clinically healthy Standardbred trot ters. Procedure-Blood and plasma lactate concentrations were measured by enzymatic analyzer, and purines, uric acid and allantoin, were dete rmined by high-performance liquid chromatography. The concentrations o f metabolites were then correlated to racing time and individual perfo rmance indexes that are annually calculated from the percentage of win nings, placings, and starts rejected, average earnings per start, and the racing record. Results-Blood lactate concentration immediately and calculated cell lactate concentration immediately and 15 minutes afte r the race correlated positively (P < 0.05 to P < 0.01) with the indiv idual performance indexes. Plasma lactate concentration was not correl ated to the individual performance indexes. Uric acid concentration, i mmediately and 15 minutes after the race, was negatively correlated (P < 0.05) to the individual performance indexes, and a positive relatio n (P < 0.05) was found between the highest concentration of uric acid and the racing time. Concentration of allantoin immediately or 15 minu tes after the race did not have any significant correlation to the ind ividual performance indexes. Conclusions-Accumulation of lactate in th e blood, which was greater in the superior performing horses. may prov e to be an useful predictor of anaerobic capacity. The results also in dicate that the loss of purine nucleotides was less in the superior pe rforming horses. although further studies are needed to confirm this.