Relationship between slope of the plasma lactate accumulation curve and working capacity in Andalusian horses

The main objective of this study was to analyse the relationship between th e slope of the plasma lactate accumulation in response to exercise and work ing capacity in two groups of Andalusian horses of different age. The horses were subjected to increasing intensity tests, comprising both su bmaximal and maximal velocities. Heart rate was monitored throughout the ex ercise and jugular venous blood samples were withdrawn at rest, after each workload and during the first 30 min, of recuperation. Working capacity was assessed by means of these functional indices: HRmax (maximum mean heart r ate during exercise), Vmax (maximum velocity), STEPmax (maximum number of w orkload completed), VLA2 (aerobic threshold), VLA4 (anaerobic threshold), P LA (lactate peak), pHmin (minimum pH) and PCVmax (maximum packed cell volum e). HRmax, pHmin, VLA2, VLA4, STEPmax and Vmax were positively correlated with working capacity, whereas PLA and PCVmax were negatively correlated with wo rking capacity. The slope of the plasma lactate accumulation curve were inv ersely related to VLA2, VLA4, Vmax, STEPmax and pHmin and positively relate d to HRmax and PCVmax. Besides, the plasma lactate slope was higher in the youngest Andalusian horses. These results indicated that the slope of the plasma lactate concentrations after several exercise intensities might be considered as a marker of aero bic potential, providing useful information about fitness and training degr ees in the Andalusian horse.