Journal article

Publication year: 2001

Pages: 241-246

Journal: Pferdeheilkunde

Volume number: 17

Issue number: 3

ISSN: 0177-7726

Open access status: Bronze

DOI Link: https://doi.org/10.21836/PEM20010307

Publisher: Hippiatrik

Abstract: 

The relation between heart rate during exercise and blood lactate concentration after exercise in horses was examined. Furthermore, the predictability of the heart rate during exercise derived from the results of a standardized exercise test performed by the horses before conditioning was studied. Six thoroughbred horses were submitted to a total of six different types of exercise: 5, 15 or 25 minutes' duration at their individual v(2.5) or v(4). Each exercise type was run by a horse 11 times within a conditioning period of three weeks. All workouts were on a treadmill. The speed of exercise was determined with a multiple step exercise test before each conditioning period. The multiple step exercise test consisted of several steps of five minutes duration each with one minute rest between steps to take blood samples. The speed in the first step was 6.0 m/s, and each consecutive step speed was increased by 0.5 m/s. Slope of treadmill was set at 6%. A test was discontinued when blood lactate concentration of a horse was above 4 mmol/l. immediately after finishing an exercise bout blood was taken for lactate analysis. Heart rate was monitored continuously during exercise. From the blood lactate-running speed relation v(2.5) and v(4) were calculated by exponential regression. Exponential regression analysis was used to determine HR2.5 and HR4 also (HR2.5 and HR4 = Heart rates at which mathematically horses running at the defined conditions had a blood lactate concentration of 2.5 and 4 mmol/l).

The median heart rates during exercise at v(2.5) for 5, 15 and 25 minutes were 159 beets/min, 157 beats/min and 160 beats/min respectively.After exercise at v(4) for 5, 15 and 25 minutes they were 163 beats/min, 166 beats/min and 164 beats/min respectively. The heart rate during exercise of the same duration was always higher after exercise at v, than at v,, (p < 0.01 to p < 0.001). The effect of exercise duration on heart rate during exercise was very small. Between and within horses there were large variations of the heart rate during exercise. The blood lactate concentration after exercise and the heart rate during exercise related in three out of six exercise types only. The relations were not very close and in one case it was positive and in the other two negative. Thus it does not make sense to guide exercise intensity by a defined heart rate during exercise if it is aimed to condition a specific energetic pathway.

To evaluate the predictability of heart rate during exercise the difference was calculated between the measured and the expected values HR2.5 or HR4. The median of the difference between measured and expected heart rate during exercise was for exercise at v(2.5) for 5, 15 and 25 minutes +1 beat/min, -2 beat/min und -2 beat/min respectively, for exercise at v, for 5, 15 and 25 minutes it was -7 beats/min, -2 beats/min und -3 beats/min respectively.

Despite the large day by day and interindividual variations of the heart rate during exercise guidance of exercise intensity by means of heart rate derived from exercise tests may be reasonable. However, studies to demonstrate whether this approach is effective and better than other methods await to be done.

Harvard Citation style: Lindner, A., Sobotta, M. and Sasse, H. (2001) Predictability of blood lactate concentration after exercise in horses working at speeds that were guided by results of on exercise stress test. Part 2: Relation between heart rate during exercise and blood lactate concentration after exercise, Pferdeheilkunde, 17(3), pp. 241-246. https://doi.org/10.21836/PEM20010307

APA Citation style: Lindner, A., Sobotta, M., & Sasse, H. (2001). Predictability of blood lactate concentration after exercise in horses working at speeds that were guided by results of on exercise stress test. Part 2: Relation between heart rate during exercise and blood lactate concentration after exercise. Pferdeheilkunde. 17(3), 241-246. https://doi.org/10.21836/PEM20010307