Exercise tests in saddle horses. 1: Comparison of step tests on a track and an inclined treadmill

Summary The purpose of this study was to compare the physiological responses of horses performing the same standardized exercise test, first in field conditions with a rider, and then on an inclined treadmill set at a 3.5% slope. Five saddle horses trained for three-day-event competition performed an exercise test consisting of five 3 min steps of increasing speeds (1.6, 4.2, 7.5, 8.3, 9.2 and 10 m/s). Following each step, blood samples were taken by jugular venipuncture during a 1 min rest period to determine blood lactate concentration (La). During the incremental test, the heart rate was recorded and the data averaged for each step. The exercise tests were carried out first on the fiat turf track and then one week later on the treadmill. No significant difference appeared between the mean heart rates (158.4 vs 158.5 beat/min; 171.0vs 167.8; 180.3 vs 178.9; 192.0 vs 190.2) and the blood lactate concentrations (1.03 vs 1.22 mmol/l; 1.73 vs 1.70; 2.99 vs 3.12; 5.38 vs 4.98) obtained at 7.5, 8.3, 9.2 and 10 m/s in overground and treadmill conditions, respectively. The velocity-dependent changes in the heart rate and blood lactate concentration were similar and the exercise parameters (V170, V200, VLa 3 and VLa4) did not differ significantly between the two exercise test conditions. It was concluded that a slope of 3.5% could simulate the workload of an incremental test performed by saddle horses running on a track with a rider.