Evaluation of physiological responses of cardiac and blood parameters after incremental exercise on field and laboratory tests in eventing horses

Abstract

This study was carried out to model data of plasma lactate and glucose concentrations, heart rate and haematocrit in eventing horses after incremental speed tests on the field and on a high speed treadmill. The experimental design was a duplicate Latin square, with two tests, on the field and on a treadmill. Eight eventing Brazilian Sport Horses were used, five males and three females, with mean age of 7.4 years old, and average body weight of 479 kg. The protocol for the incremental speed test on the treadmill consisted of 10 minutes of warm up walking and trotting; followed by gallops at initial speed of 5.0 m/s, with increments of 1.0 m/s every minute up to 10.0 m/s. The treadmill inclination was 4% during the gallops. At the end of the test, horses were trotted at 4.0 m/s during 4 minutes, walked at 1.7 m/s during 6 minutes and rested thereafter on the treadmill. The protocol used on the field test consisted of 10 minutes of warm up walking and trotting; followed by 4 steps of one minute at 5.0, 7.0, 8.0 and 10.0 m/s, with 3 minutes intervals of walking recovery between each step. After the test the horses recovered at rest and were monitored during 60 minutes. An exponential regression described the reduction of plasma lactate concentration and heart rate better than a linear regression. The reduction of the haematocrit was better described by a linear regression. It was not possible to adjust plasma glucose concentration during recovery from exercise test on a regression equation because there was no difference (P>0.05) among its mean values.