Impact of training load on the heart rate of horses

The heart rate of horses at rest depends mainly on the degree of relaxation and health. The heart rate of horses in rest is normally within the range of 25–40 beats per min. The sudden excitement, fear and expected training can quickly increase the heart rate to above 100 beats per min (Evans, 2007; Hamlin et al., 1972). As reported by Littlejohn (1987), Marr and Burton (2010) achieving of resting heart rate values is lower in trained horses than untrained horses. However, generally by Poole and Erickson (2004), Burton (2010) applies that the rest heart rate is not reduced after training in the horse as well as in human athletes. The use of heart rate to monitor condition is limited to measuring during exercise or after exercise. The heart rate is increasing rapidly at the beginning of the exercise and reaches a steady state in 2–3 minutes (Evans, 2007; Marr and Burton, 2010). Based on studies Poole and Erickson (2004), Young (2004) reported that this increase was associated with increased sympathetic activity of the nervous system and the release of adrenaline. Steady state by Engelhardt (1977) and Young (2004) remains constant during the submaximal workloads. At the beginning of the load may occur exceeding of the heart rate above the level that is steady in the submaximal load (Persson, 1967; Persson and Lydin, 1973). The average time needed to achieve the maximum heart rate in the training of Thoroughbred was 22 seconds (Krzywanek et al., 1970; Young, 2004). The trotting did not achieve the maximum heart rate at a speed from 12 to 12.5 meters per second (m/s) neither after riding 700 m (Courouce et al., 2002; Lindholm and Saltin, 1974). The kinetics of the heart rate at the beginning of training without the previous warming depends on intensity of training (Evans 2007; Poole and Erickson, 2004).


Introduction
The horses compared to other mammals have higher maximum oxygen consumption in relation to the body weight.One contraction from the heart of trained horse print over 1 liter of blood.The maximum values of blood flow during the load are at the level of 300 l min -1 .
The heart rate of horses at rest depends mainly on the degree of relaxation and health.The heart rate of horses in rest is normally within the range of 25-40 beats per min.The sudden excitement, fear and expected training can quickly increase the heart rate to above 100 beats per min (Evans, 2007;Hamlin et al., 1972).As reported by Littlejohn (1987), Marr and Burton (2010) achieving of resting heart rate values is lower in trained horses than untrained horses.However, generally by Poole and Erickson (2004), Burton (2010) applies that the rest heart rate is not reduced after training in the horse as well as in human athletes.The use of heart rate to monitor condition is limited to measuring during exercise or after exercise.The heart rate is increasing rapidly at the beginning of the exercise and reaches a steady state in 2-3 minutes (Evans, 2007;Marr and Burton, 2010).Based on studies Poole andErickson (2004), Young (2004) reported that this increase was associated with increased sympathetic activity of the nervous system and the release of adrenaline.Steady state by Engelhardt (1977) and Young (2004) remains constant during the submaximal workloads.At the beginning of the load may occur exceeding of the heart rate above the level that is steady in the submaximal load (Persson, 1967;Persson and Lydin, 1973).The average time needed to achieve the maximum heart rate in the training of Thoroughbred was 22 seconds (Krzywanek et al., 1970;Young, 2004).The trotting did not achieve the maximum heart rate at a speed from 12 to 12.5 meters per second (m/s) neither after riding 700 m (Courouce et al., 2002;Lindholm and Saltin, 1974).
The kinetics of the heart rate at the beginning of training without the previous warming depends on intensity of training (Evans 2007;Poole and Erickson, 2004).
The heart rate is a fairly reliable indicator of training intensity and it is possible to manage the training effectively according to it (Leino et al., 2010).For the load in light intensity according to Schmidt et al. ( 2010) is characterized by heart rate lower than 100 beats min -1 (55-70% SFmax), moderate intensity of load corresponds to the pulse frequency at the level of 100 to 124 beats min -1 (70-80% SFmax), higher intensity of load is usually characterized by the heart rate in range of 124 to 150 beats min -1 and frequency above 150 beats min -1 is high intensity of load.Dobšák et al. (2009) stateed that the value of the pulse rate, can vary in the range 50-150% of average values, depending on the way of performing the movement.

Results and discussion
The importance of recording the heart rate during training, or the competition based on the knowledge that there is a direct relationship between heart rate and the achieved performance of horse.In general, the higher is pulse rate, the higher is the physical or mental load.
The Figure 1 shows the average heart rate of tested horses.Physiological values of horse heart rate in walk lie in the range 60 to 90 beats per minute, which is according to Dobšák (2009) on the low loads level or generally characterized as a light load.The measured values did The aim of this study was to analyse the effect of training load on the horses heart rate in simulated load by the loading regulator for horse motion.

Material and methods
In the experiment 8 Slovak Warmblood horses (3 mares, 4 geldings, 1 stallion) aged 6-10 years were observed.All horses were housed in the box stable and used in light work 1 hour per day.Body weight of tested horses was 550 ± 20 kg.They were fed three times a day (oats 3.5 kg per horse hay 10 kg per horse) during the monitored period.and Veicteinas, 2003).Tested horses achieved bradycardia after three weeks, when the decrease of heartbeats was 7 beats per min.This rapid onset of bradycardia may be explained by a good condition of tested horses and systematic training, which is essential for achieving any success.
The maximum values of heart rate (Figure 2) of all tested horses were about twice higher compared to the average heart rate.Differences of maximum heart rate values were not statistically significant (P >0.05) between first and second part of experiment.Measured maximum heart rate is by the authors Hanák and Olehla (2010) described as medium load level.As in the evaluation of the average heart rate, also the value of the maximum heart rate at the same horses were more pronounced heart rate values than at the other monitored subjects, which is according to the authors Dobšák (2009), Marr and Burton (2010) upper-middle load level.
not exceed this range in any of the monitored subjects.
Only one monitored stallions and one mare achieved average values just above the level 70 beats per minute.
But neither these values are not above the physiological level, which is characterized as a light load, which is in compliance with the findings of Freeman et al. (2006).
The results of the second part of the experiment show that the tested horses achieved an average heart rate lower than in the first part of the experiment, despite the higher load through the speed and increase percentage.Differences between first and second part of experiment in the parameter average heart rate were not statistically significant (P >0.05).The achieved values declare the beginning of adaptation of the organism to a potential load after three weeks, which is comparable to Cross et al. (2008), Voss et al. (2002).A similar conclusion was reached by Mohr et al. (2000)  The values of maximum heart rate also confirmed the fact that the adaptation of organism to the training load becomes after three weeks of systematic work.It also confirmed that the systematic training of horses decreases heart rate in a few weeks after the start of training load.
In our experiment, we recorded the decrease by 17 beats min -1 in average maximal heart rate of tested horses.

Conclusions
The training process significantly affects the internal environment for the horse.The results of our experiment show that the analysis of heart rate did not recorded statistically significant differences (P >0.05) between tested horses.Acquired values confirm that tested load did not caused any physiological changes and its length and load level were well chosen for achieving a higher level of tested horses training.Simultaneously from the course of the observed values of average and maximum heart rate can be concluded that the onset of adaptation of the organism to the training load starts after three weeks of systematic training.
The load experiment was conducted by the loading regulator for horse motion Horse Gym 2000 controlled with the computer unit.Load regulator for horse motion is equipped with an entrance and exit ramp.The strip is made of non-slipe rubber.Load regulator is controlled by a computer unit through which you can select up to 99 separate programs.