Impact of Exercise on Vitals in Racing Horses 

Different types of exercise can exert various effects on a horse’s vital signs, which encompass heart rate, respiratory rate and body temperature (De Solís, 2019; Farooq et al., 2019; Soroko et al., 2019; Padalino and Raidal, 2020). These effects are contingent upon several crucial factors. First and foremost, the intensity of the exercise plays a pivotal role; activities of higher intensity, such as galloping or jumping, tend to prompt a more rapid escalation in both heart rate and respiratory rate when compared to more moderate exercises like walking or trotting. Secondly, the duration of exercise also has a notable impact; protracted periods of physical exertion can lead to an elevation in both heart and respiratory rates, as the horse’s body works diligently to meet the heightened oxygen demands of its muscles. Moreover, the horse’s fitness level is a significant determinant, with well-conditioned horses generally exhibiting lower baseline heart and respiratory rates and a swifter recovery post-exercise (Harkins et al., 1993). Environmental conditions, encompassing factors like temperature, humidity and altitude, further influence these vital signs, with hot, humid conditions intensifying sweating and respiratory effort  and high altitudes affecting oxygen availability (Verdegaal et al., 2021; Logan and Nielsen, 2021). The age and health status of the horse also factored in, with younger horses and those with underlying health concerns demonstrating distinct responses (De Mare et al. 2017; McKeever, 2002).
     

Ethical guidelines
 
All of the procedures were carried out in accordance with the Turkish legislation on animal care (Animal Protection Law No 5199). The information about the horses was obtained from the pedigree records kept by the Turkish Equestrian Federation. The study was approved by Selçuk University Faculty of Veterinary Medicine Experimental Animal Production and Research Center Ethics Committee (Decision no: 113, Date: 15.10.2023).
 
Materials
 
In 2023, a random selection of horses was used for the research. The study’s animal sample included horses of different ages from various equestrian sports in Adana (Adana Yavuzstar Equestrian Club), Mersin (Soli Equestrian Club) provinces. January 1, 2023 and August 10, 2024 were the dates of the study. The animal material of the study consisted of 20 different horses (10 Thoroughbred, 2 Arabian, 8 Belgian), each characterized by their unique set of attributes. These horses varied in age, with the youngest being 2 years old and the oldest at 18 years. The gender distribution leaned slightly towards males, with 12 males and 8 females. Coat colors varied, with a range including Bay, Dapple Gray, Chestnut and Black. Horses were housed in similar conditions of care and they were healthy. The horses stay individually in their stables which are standardly 4 m x 3 m in size. Feeding is done in the morning, noon and evening and their daily feed is consisted of 4 kg of oats, 2 kg of barley, 1 kg of ready-made feed with a high vitamin, mineral and protein ratio, 6 carrots, 6 apples and 10 kg of hay. In the farms, water troughs are in the paddocks and stables.
 
Physical exercises and physiological parameters
 
In this study, a comprehensive examination of horses’ physiological responses during and after exercise sessions was conducted. The study encompassed the measurement and recording of key parameters, including pulse rate (heart rate), respiration rate (breathing rate) and body temperature, at various critical time points: before the commencement of exercise, immediately post-exercise, 30 min after exercise and 1 hour after exercise. The exercise aspect of the study covered a spectrum of variables. Exercise duration varied between 15 to 40 min, with each session commencing with a standardized warm-up period of approximately 5 min, including a rider on the horse. The exercise type was categorized into three distinct categories: lunge, free ride, or show jumping. Additionally, the type of ground or surface on which the exercise occurred was classified as either grass or sand (Table 2). Notably, this study benefited from the collaboration of horse owners, trainers and caretakers in collecting comprehensive data, ensuring a holistic and practical approach. Crucially, the horses in the study were not anesthetized, affirming that all measurements were obtained from conscious and unaltered animals. The horses were observed at four specific time points: when they were at rest in their stalls (Time I), immediately after completing the exercise (Time II), half hour after the exercise (Time III) and one hours after the exercise (Time IV). During these observation periods, the researchers collected data on the horses’ heart rate, respiratory rate and rectal temperature. In addition to this, the horses were recorded on video, allowing for the development of a focal animal sampling ethogram to assess their behavior (Padalino et al.,  2014).

 

At the end of the study, the working floor, working time, working type and body temperatures of the horses according to age, race, gender and frost color were measured before, after, 30 minutes after and 1 hour after the study given in Table 1. When the table was examined, it was found that the body temperature was statistically significantly different only after the study according to the age factor (P0,05). At the end of the study, the body temperatures of horses with an age range of 11-20 were found to be higher than other horses (38,6500±0,33166). According to the age factor, the body temperature could not reach the pre-study level in horses between the ages of 2-5 even after 1 hour, while it fell to a lower level of pre-study body temperature in other horses. This result is normally an expected result (Ruben and David, 2007). Again, it was observed that older horses exercised for a longer time (31,250±8,5391).


 
When examined according to the race factor; It is seen that the exercise time of Arabian horses is longer (30,000±0,0000). As for body temperature, it was determined that English horses were more variable (38.1800±0.65625).  When examined according to the sex factor, female horses exercised more (31,500±5,2967), although the body temperature reached the pre-exercise state in male horses 30 minutes after exercise, it increased in female horses.
 
Statistically, body temperature was found to be significantly different in horses according to coat color, 1 hour after exercise (p0, 05). When the exercise periods are examined, it is seen that Black horses work more time (32,500±9,5743), while Bay horses work the least (24,000±8,2158). It was determined that the highest Black (37.5500±0.96782) horses had the lowest Black (36.9600±0.45607) horses according to body temperature. It is observed that 1 hour after the exercise, the body temperature drops below the initial level in all horses except Dapple Gray. Body temperature after training varies individually in horses (Ruben and David, 2007).
 
The pulse values of the horses in the study according to age, race, gender and frost color before, after, 30 minutes after and 1 hour after the study values are shown in Table 2. it is also given. Although the pulse values were statistically insignificant according to the age factor (P0, 05), it was determined that the pulse values of young horses were lower (23,2000±5,01996). When pulse values were examined according to races, it was found that the pre-exercise pulse values were statistically significantly different (P0, 05). Arabian horses have the lowest pulse value before exercise (19,0000±1,41421), while Belgian horses have the highest value (28,0000±3,89138). When the pulse rate according to gender was examined, it was found that female horses had a higher level (26,0000±5,37484) before training and a higher level (32,2000±8,53490) compared to male horses after training. Nevertheless, the pulse values returned to normal 30 minutes after training in horses of both sexes, which indicates that the horses are healthy (Marsland 1968). According to the coat color observed in the horses, the pulse rate returned to its normal level 1 hour after training.


 
The values of the number of respiratory rate before, immediately after, 30 minutes after and 1 hour after training are given in Table 3. When the table was examined, it was determined that the respiratory rate of horses decreased with age according to the age factor. According to these data, the movement level decreases due to the progression of the horses’ age and as a result, the number of respiration is also high in young people (Ruben and David, 2007). When the number of respiration was examined according to the breeds, the lowest (23,4000±4,03320) value was observed before training in the Thoroughbred breed, while the highest (37,3000±12,59674) value was reached after training. Sudden changes in the number of breaths are observed in Thoroughbred and Standardbred horses due to the instantaneous acceleration property that we call explosion power (McCutcheon et al. 1999). It has been determined that the respiration rate according to the breed is at a lower value in females compared to male horses. When the respiration rate relative to coat color in horses was examined, it was seen that although the respiration rate was low in horses with bay coat color at the beginning, it increased to the highest level at the end of the study. It can be said that these values are normal due to the fact that the thoroughbred breed horses found in the study mostly have bay coat color.


 
From the dataset, it appears that the age of the horses did have some influence on their physiological responses to exercise.   In terms of temperature, older horses generally tended to exhibit a smaller increase in body temperature immediately after exercise compared to younger horses. The body temperatures of horses with an age range of 11-20 were found to be higher than 2-10 age range other horses immediately after exercise. For instance, horse number 1, the oldest horse at 18 years, experienced a temperature increase of 2.4oC after exercise, while younger horses like horse number 16 (2 years old) had a smaller increase of 0.5oC. This suggests that older horses may have a reduced ability to dissipate heat during exercise. Thoroughbred horse named Wanessa was exercised on grass and a sudden increase in body temperature and pulse rate was detected after the exercise. Similarly, the sudden increase in the values of Victoria working on the sand ground was also noticeable. Some older horses (10-18 age range) showed a more significant increase in pulse rate immediately after exercise compared to younger ones (2-10 age range). For example, Horse Number 1 (18 years old) had a pulse rate increase of 20 beats per minute, while Horse Number 16 (2 years old) had a smaller increase of only 2 beats per minute. This indicates that older horses may have a more pronounced cardiovascular response to exercise. The impact of age on respiratory rate was variable. Horse Number 1 (18 years old) exhibited a substantial increase in respiratory rate, suggesting a heightened response to exercise, while Horse Number 16 (2 years old) had a relatively modest change in respiratory rate. This implies that the influence of age on respiratory responses may vary among individual horses. The extended lifespan of horses has spurred research interest in exploring how aging influences the typical physiological processes in equines (Anggraeni and Muhammad, 2024; Jarvis et al., 2017; Ralston, 2006; Ralston and Breuer, 1996; Verdegaal et al., 2024). In this study, it was observed that aging causes physiological changes in horses.
 
One of the important point was the nutrition same of the horses considered in the present study. In our study, the diet of the horses was the same. It was thought that it would be appropriate to develop feeding models according to age. In the case of older horses, there is substantial evidence indicating a reduction in both maximal oxygen capacity and exercise performance (Betros et al. 2002; Seals, 1993). This decrease in maximal heart rate may impose limitations on their ability to engage in demanding physical activities (Taffett, 2003). Remarkably, McKeever and Malinowski’s research unveiled that submaximal oxygen consumption levels were relatively consistent between young and old horses during an incremental exercise test. However, it was observed that older horses expended less effort to reach this submaximal oxygen consumption level compared to their younger counterparts (McKeever and Malinowski, 1997; Malinowski et al., 2002).
 
Padalino et al. (2014) conducted a research study with the aim of investigating how various physical exercises impact the physiological and behavioral responses of Standardbred trotters (Seals 1993). Acording to this study all the physiological parameters measured showed an increase following exercise, with the extent of increase correlating with the intensity of the exercise (Padolino et al. 2014).
 
Horses participating in various exercise types exhibited differences in temperature changes immediately after exercise. For instance, horses engaged in show jumping exercises often showed notable temperature increases compared to those in free rides or lounge exercises, indicating that the intensity and nature of the exercise type influenced thermal regulation. Miraglia et al. found a positive correlation between the increase of temperature and exercise intensity (Miraglia et al., 2000). Since it is well known that thermoregulation is impaired in poorly trained horses (Hodgson et al., 1994).
 
The exercise type had a pronounced effect on pulse and respiratory rate changes. Horses involved in activities like show jumping generally displayed more significant increases in pulse and respiratory rate immediately after exercise compared to horses engaged in free rides or lounge exercises. Horse Number 7 (Thoroughbred, Male, Age 7) experienced a remarkable increase in pulse rate (from 20 to 23 beats per minute) and a considerable rise in respiratory rate (from 26 to 32 breaths per minute) immediately after exercise. This suggests that the cardiovascular demand and intensity of exercise varied depending on the type of activity. In contrast, horses participating in free ride exercises, like Horse Number 8 (Hanoverian, Female, Age 9), demonstrated a milder pulse rate increase (from 28 to 30 beats per minute) and a moderate change in respiratory rate (from 30 to 27 breaths per minute) immediately after exercise, indicating a different physiological response compared to show jumping. The dataset illustrates that exercise type significantly impacted the horses’ physiological responses, emphasizing that the nature and intensity of the exercise play a crucial role in shaping how horses respond in terms of temperature regulation, cardiovascular responses (pulse rate) and respiratory function. The pulse value has the highest change in Thoroughbred horses. It is normal for the pulse to rise rapidly in high-burst sprint horses such as Thoroughbred and Standardbred (McCutcheon et al. 1999).

The duration of exercise significantly influenced physiological responses. Longer exercise periods were associated with more pronounced changes. For instance, Horse Number 7 (Thoroughbred, Male, Age 7), engaging in a 40-minute show jumping exercise, exhibited a notable increase in respiratory rate (from 26 to 32 breaths per minute) immediately after exercise, indicating the prolonged respiratory effort. In contrast, Horse Number 3 (Thoroughbred, Male, Age 6), involved in a shorter 15-minute Lounge exercise, had a relatively modest change in respiratory rate (from 26 to 27 breaths per minute), illustrating the impact of exercise duration on respiratory responses.
 
The choice of exercise ground had an impact on the horses’ physiological responses. Horses exercised on different ground surfaces (sand or grass), displayed variations in temperature changes immediately after exercise. For example, some horses exercised on sand exhibited more substantial temperature increases compared to those on grass, suggesting that the ground surface played a role in thermal regulation during exercise. While the effect of exercise ground on pulse rate changes was less consistent across the dataset, some horses on specific ground surfaces experienced more pronounced increases in pulse rate after exercise. Exercise ground also appeared to affect respiratory rate changes. Horses exercised on sand, for instance, often exhibited slightly higher increases in respiratory rate compared to those on grass.
 
The temperature values 1 hour after exercise vary among the horses, but they are generally closer to the pre-exercise values.  The pulse rate values 1 hour after exercise also show variability among horses. Some horses, like Horse 7, exhibit pulse rates that are similar to their pre-exercise values, while others, like Horse 12, show a slight decrease in pulse rate compared to the immediate post-exercise values. Overall, there is no significant deviation from pre-exercise baseline pulse rates 1 hour after exercise. The respiratory rate values 1 hour after exercise vary among the horses. Some horses show respiratory rates that are similar to their pre-exercise values, while others exhibit different rates. For example, Horse 1 had a respiratory rate of 16 breaths per minute before exercise and 1 hour after exercise, indicating a return to the baseline level. In contrast, horse 7 had a respiratory rate of 26 breaths per minute before exercise, which increased to 28 breaths per minute 1 hour after exercise, indicating a slightly elevated respiratory rate. Overall, the data suggests that respiratory rates 1 hour after exercise vary among horses and not all horses returned to their pre-exercise baseline levels. It has been seen that similar results were obtained with the studies conducted (Farooq et al. 2019; Padalino and Raidal, 2020).

In conclusion, the analysis of the dataset on horse physiological responses to exercise underscores the multifaceted impact of exercise type, exercise period and exercise ground on equine well-being. These factors play pivotal roles in shaping the horses’ temperature, pulse rate and respiratory rate, reflecting their dynamic adaptability to various training regimens and environmental conditions. Exercise type revealed distinct physiological signatures, with activities like show jumping invoking more substantial cardiovascular and respiratory demands compared to free rides or lounge exercises. This insight emphasizes the importance of tailoring exercise programs to the specific needs and abilities of individual horses, taking into account their chosen activities. The duration of exercise also exerted a noticeable influence, with longer exercise periods resulting in more pronounced physiological changes. Horses on sand often exhibited slightly higher post-exercise temperatures and respiratory rates, suggesting that the ground surface plays a role in thermal regulation and breathing patterns. These findings collectively highlight the intricate interplay of exercise type, duration and ground surface in shaping equine physiological responses. Horse owners, trainers and veterinarians can benefit from this knowledge to optimize exercise regimens and safeguard the health and performance of their equine companions. By considering these factors, we can ensure that our horses thrive in their training environments and achieve their full potential while maintaining their well-being.
 

Any financial support, technical assistance or other contributions to the study are gratefully acknowledged.
 
Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
Informed consent
 
All animal procedures for experiments were approved by the Committee of Experimental Animal care and handling techniques were approved by the University of Animal Care Committee.
 
Author contributions
 
Y and M contributed to the data acquisition, interpretation of data and wrote the manuscript. All manuscript authors have read the manuscript and approved it for submission.

The authors affirm that they have no conflicts of interest related to the publication of this paper. None of the authors involved in this research have any financial or personal affiliations with individuals or organizations that could potentially exert undue influence or introduce bias into the paper’s content.