MAXIMAL LACTATE CONCENTRATIONS IN HORSES AFTER EXERCISE OF DIFFERENT DURATION AND INTENSITY

Lactate kinetics in whole blood of horses was investigated after exercise of differing velocities and duration. The following categories of exercise were used: A: < 11 m/second and > 180 seconds (n = 35), B: > 11 m/second and < 180 seconds (n = 17) and C: < 11 m/second and < 180 s (n = 10). The mean peak lactate concentration determined in horses in category A was 4.49 +/- 2.21 mmol/l, in B, 16.32 +/- 4.81 mmol/l and in C, 4.58 +/- mmol/l. While the maximum lactate concentrations in categories A and C were always found immediately after the exercise, the peaks in category B were measured between the first and tenth minute after exercise. Mean lactate concentrations measured at 2-minute intervals after bouts of category-B exercise tended to stabilize 3 to 10 minutes after exercise; however, mean lactate concentrations measured during the intervals before and after the peak value differed significantly. The lactate concentration returned to pre-exercise levels within 20 minutes after exercise bouts of category C, but remained above pre-exercise levels up to 60 minutes after bouts of category-A and -B exercise. It was concluded that, for an evaluation of lactate data after intensive anaerobic exercise, sequential blood sampling at 2-minute intervals for a period of up to 12 minutes after exercise is necessary. Less frequent sampling may be a reason for the often described irreproducibility of lactate concentrations in horses. After aerobic or mild anaerobic exercise, one sample is sufficient, but it has to be taken as soon as possible after exercise.