Analysis of movement mechanics in the training process of sport horses

© Slovak University of Agriculture in Nitra Faculty of Agrobiology and Food Resources

load controllers. The treadmill was first used in horses (Persson, 1967) and has become an important tool in various researches and accessory in veterinary experiments, because it allows the mechanics of the movement to be recorded with high accuracy. Swedish warm-blooded horses shown shorter lengths of steps (Fredricson et al., 1983) compared with French riding horses where elongation of steps was noted (Barrey et al., 1993). Also in studies focusing on horse performance, such as Straub and Hoppeler (1989) found differences in treadmill and riding training and assumed that horses needed less energy for performance on the treadmill. Connected to this issue, the aim was to evaluate the impact of the training process on quantitative and qualitative indicators of motion mechanics.

Experimental setup
The experiment was carried out in Experimental centre at Department of Animal Husbandry, Faculty of Agrobiology and Food Resources (Slovak University of Agriculture, Nitra, Slovakia). Experiment was performed exclusively in the mornings, and the observed animals were tested in the same order. The load test was performed on a HorseGym 2000 horse motion regulator. The regulator is controlled by a computer unit, where time interval in minutes (min), speed (km/h) and smooth ascent of the belt (°) can be set. In order to comply with the principles of welfare and health safety under load, the device is equipped with safety sensors, which in the event of disturbance of horse stability will immediately stop the load regulator.

Biological material
In the experiment we analyzed 14 horses of the Slovak Warmblood breed, which is the most widespread breed in Slovakia and is most used in equestrian sport. The tested horses were housed in a box housing with sawdust bedding, fed thrice a day with a complete feed mixture balanced according to each animals weight and light amount of load. Bulk feed was fed in the morning and in the evening ad libitum. The tested horses weighed 575 ±25 kg and before the training underwent training with light load for the duration of 12 months. Horses that took part in the experiment were divided into three groups based on sex -3 stallions, 5 geldings and 6 mares; and based on age into another three groups -up to 7 years of age (7 individuals), 8-14 years old (3 individuals) and horses older than 15 years (4 individuals).

Division of training activities over the duration of the experiment
The training load was divided into three stages. Each stage of the experiment lasted for 2 weeks with the following length, speed and degree of load: Stage 1 lasted for total of 35 minutes and consisted of following activities: 20 minutes walking with 0° elevation, 4.9 km/h; 15 minutes walking uphill with elevation of 3°, 4.9 km/h. Stage 2 lasted for total of 45 minutes and consisted of following activities: 20 minutes walking with 0° elevation, 4.9 km/h; 10 minutes walking uphill with elevation of 3°, 4.9 km/h; 10 minutes walking uphill with 4° elevation; 4.9 km/h; 5 minutes uphill with 6° elevation, 4.9 km/h. Stage 3 lasted for total of 25 minutes and consisted of following activities: 5 minutes waling with 0° elevation, 5.8 km/h; 5 minutes walking uphill with 3° elevation, 5.8 km/h; 5 minutes walking with 5° elevation, 5.8 km/h; 5 minutes walking with 7° elevation, 5.8 km/h; 5 minutes walking with 0° elevation, 5.8 km/h.

Evaluation of movement mechanics during individual stages of training load
We monitored the parameters of the motion mechanics in all training stages of the experiment, including: the number of steps and the length of the step (m). The number of steps was determined using an ACRA LTH5 pedometer, attached to the wrist of the left forelimb. From the measured number of steps and the travelled distance, we calculated the average length of step in meters.

Statistical analyses
Statistical programme SAS 9.3, Enterprise Guide 5.1 (SAS Institute Inc. 2011) was used for statistical processing of background data. The Analysis of Variance (ANOVA) was used to assess the effect of stage of load training and age of horses on the number of steps and step length, with testing the contrasts by means of the Scheffe test at the level of significance p <0.05. The analysis was performed according to the following model equation where: Y ijkl -number of steps and step length, µ -overall mean, LT i -stage of load training (n = 3; stage 1; stage 2; stage 3), AC j -age category (n = 3; up to 7 years; up to 14 years; over 15 years), G k -gender (n = 3; stallion, mare, gelding), e ijkl -random error

Results and discussion
Number of steps parameter reflected in statistically significant difference (p <0.05) between the individual stages. The most significant increase was observed between first and second stage of load, where the increase was up to 833 steps (Figure 1).
The second load stage represented a significant increase in load for the horses, as the horses were tested for 10 minutes longer in ascent, and the load levels was twice higher compared to the first stage of load. Results of measuring the third stage of load confirm that tested horses have continually adapted to the set load. This assumption is also confirmed by the measured values of "number of steps" parameter where we observed a significant decrease of steps number in third stage load and also a statistically significant difference (p <0.05) in length of step between individual stages of load in favour of third stage load ( Figure 2). Similar conclusion was reached by Barrey et al. (2016) in terms of reducing the number of steps in the treadmill load and extending the step length, who compared the number of steps and the length of steps in horses trained on treadmill and in the riding hall with the saddled horses.
Evaluation of the movement mechanics in terms of spaciousness we recorded a slight but statistically significant (p <0.05) increase in all tested horses favoring the increasing degree of load. These values confirm the fact that the mechanics of horse movement are positively adjusted by systematic and regular training (Mlyneková et al., 2016). Parkes et al. (2019) in their experiment noticed that a non-linear pattern of stried length occured in two-year-old horses, which was initially stortened and the leveled off over time. At the end of the experiment, tested horses showed an extension in stride length by 0.22 m. Becero et al. (2020) state that nine horses tested on treadmill shown progress in step regularity and the reached a longer length and lower step frequency, as confirmed by our findings. In addition to the monitored external factors such as the degree of load, we also analysed the effect of gender and age on the number and length of steps. From obtained data, we can state that gender did not affect the movement mechanics, which is documented by statistically insignificant differences (p >0.05)

Conclusions
Gradual increase of the training load led to the economization of movement, which was manifested by the prolongation of the horse´s step, regularity of the movement and significant energy of the pelvic limbs. During a long-term training process, the organism was adapted to repeated stress. From the results obtained in the experiment, we can state that the load chosen by us represents a level that has a positive effect on the spaciousness of the horse´s movement. In order to achieve faster performance progress, it is possible to increase the training load without any major problems without compromising the welfare of the horses.