Why should you measure the racehorse’s heart rate? How do you monitor data during the horse’s training? How to improve recovery to reach excellent fitness and prepare the horse to race?

The aim of this guide is to provide you with all the keys necessary to analyse the racehorse’s heart rate. Improving performance is an important subject for any trainer, owner, and professional in the racing world. The arrival of data in the industry provides new key, objective, and necessary information to implement winning racing strategies.


Just as humans, the racehorse’s heart rate is the rhythm of his heartbeat. The cardiovascular system is made up of the heart and blood vessels. It ensures efficient blood circulation and the transport of a large volume of oxygen, mostly to the muscles. The volume of blood that the heart ejects with each beat during cardiac contraction (systolic ejection volume) is more than one litre in racehorses. The weight of the heart represents about 1% of a horse’s mass and training will tend to increase hiscardiac mass by about +15%. This improves his cardiac capacity and allows the heart to get less tired by beating more slowly for the same amount of work.

Thus, measuring the heart rate of racehorses provides information on their level of fitness and their adaptation to training.

Maximum heart rate (HRmax)

The maximum volume of oxygen (VO2 max) which a horse can use is one of the best indicators of his level of performance. Heart rate is strongly correlated to the volume of oxygen consumed by the body.

Once the HR Max is reached, there is little left for the horse to accelerate and reach his VO2 max. The horse has to draw on his other energy sources to be able to accelerate. However, as other sources of energy are limited in quantity during a race, horses can maintain their maximum speed for about 600 to 800 metres.

The maximum heart rate can be measured during exercise where the intensity requires a significant amount of energy. Typically, a maximum speed effort of 70% to 80% over at least 1600m or on a track with a positive altitude gain, or strength greater than 90% of maximum speed over 600m.

It decreases slightly with age and is very little influenced by training. Furthermore, it is not correlated with the performance level of a horse. In the same race, it has been shown that the maximum recorded heart rate of horses ranged from 204 to 241 BPM (Evans, 2007).

To gain a better understanding of the horse’s work and to train horses within their own heart rate ranges, it is advised to assess their maximum heart rate at least twice during the season using a veterinary supervised exercise test.

An exercise test is a way of identifying a horse’s working capacity by objectivising his response to training.

3 key insights to remember

    • It is not a fitness indicator: it does not change with training and can decrease a little bit with age
    • Each horse has his own: It is the number of beats per minute reached during maximum effort. 
    • It is a reference to assess intensity: The intensity is evaluated according to HRmax (% of HRmax).

Why is V200 important?

The V200 stands for the speed reached by the horse when his heart rate reaches 200 BPM. Best horses will have a higher V200 than others. However, this parameter should be used to compare pieces of training of the same horse rather than to compare horses with each other as they have different heart rates when exercising.

It allows quantifying the progress achieved during a training period. Indeed, if a racehorse has a higher V200 at the end of a training period, this shows an improvement in his speed abilities. He is able to run faster at the same heart rate frequency.

cardio cheval

V4 parameter

V4 or VLa4 defines the speed associated with a blood glucose level of 4 mmol/l. When a horse has 4mmol of lactate (muscle waste) per litre of blood, he reaches his V4. 

This value matches the transition point between aerobic and anaerobic effort. During an anaerobic type of effort, glucose becomes the majority source of energy creation and the lactate volume in the blood increases. 

Therefore, V4 is specific to each horse, according to his fitness level. Some breeds have a higher average V4 than others, highlighting the need to individualise training for each horse. If a horse’s V4 increases, it means that his ability to remove lactates has improved. Indeed, the faster lactates are eliminated, the better a horse can maintain his effort over time and the less risk of pain and injury. 

When the V4 increases over time, it means that the horse’s fitness and resistance to intense exercises have improved.

However, like the V200, the V4 is dependent on many exogenous factors such as the track slope, type and quality of the ground. Therefore, researchers have established a variant: the HR4. It measures the heart rate of a horse when the 4mmol/l threshold is reached. Generally situated around 170 BPM, the FC4 is therefore independent of the exogenous factors mentioned above.

Quantify your racehorse’s recovery

Recovery is one of the main parameters of a horse’s fitness: the better a horse’s recovery, the better his fitness. Analysed in parallel with the intensity of the work required, a horse’s fitness tells whether a horse is ready to run. Optimal fitness is shown by the ease with which a horse recovers and an excellent recovery during heavy work.

A horse recovering well from intense training is more likely to win his next races than a racehorse having trouble getting over an intense exercise. To assess the recovery, you need to collect heart rate data.

In order to analyse the evolution of a racehorse’s heart rate during training, 4 heart rate zones can be defined:

– A. The work zone: speed and heart rate parameters are high. This zone allows the HR level reached during the effort to be quantified. The training difficulty can be assessed by looking at what percentage of his maximum heart rate the horse has worked.

– B.  The deceleration zone at the end of training: At the end of the exercise, the speed decreases significantly, the heart rate must follow this decrease. However, it can remain high in order to compensate for the oxygen debt accumulated during effort.

récupération cardio cheval

– C. The phase of rapid decrease in heart rate – «rapid recovery»: At the end of work, after a period of heart rate maintenance (zone B) at a high level, the heart rate decreases very rapidly over a few tens of seconds (zone C). It is important to evaluate the level of return relative to the horse’s HR Max.

– D.  Slow heart rate decrease phase – «Slow recovery»: The faster the horse is, the faster the horse returns to his initial heart rate. It has been shown that the recovery time (D) is correlated with the level of performance of the horse: the lower it is, the better the horse.

Nowadays, the trainer relies entirely on his experience, his feeling and the feedback from the riders. Completing this process with objective data such as heart rate and recovery maximises the efficiency of decision-making on entry and race success, while ensuring the medical follow-up of the horse.

The better the recovery, the better the fitness.

Heart rate VS Heart rate variability

Heart rate variability (HRV) is different from the heart rate. It assesses whether the time between each beat is constant, or whether it is subject to variability, over a given period of time.

The degree of variability reflects the degree of relaxation of the nervous system. The more relaxed you are, the greater the variability between the different heartbeats; whereas the more stressed you are, or the more pain you feel, the lower the variability will be.

To sum up, it is a measure that will indicate the state of stress or relaxation of a person or a horse during a given period of time.


Collect a data historic to assess the fitness level over time 

Collecting data historic specific to each horse provides for personalised monitoring and abnormalities detection. Made up from standard value, this data historic allows for abnormal values detection, such as a poor recovery or a higher heart rate during warm up. However, this data is only comparable if it has been collected during training sessions under similar conditions. Therefore, it is important to qualify for the training sessions: track, training, weather etc.
racehorses heart rate indicators to watch for

Quantify the training workload

In an environment as competitive as horse racing, trainers strive to maximize their chances of winning at the racetrack. Quantifying the racehorse’s training workload gives undeniable advantages. The workload assessment is the volume and intensity of a horse’s training over a given period.

First, it reduces the risk of under and overtraining. By collecting objective data such as heart rate, speed, and recovery, you can monitor the training workload and ensure the effectiveness of the training. The main overtraining symptom noticeable with a heart rate monitor is the decrease in performance. The horse is no longer able to hold his effort as long as before. The heart rate remains high after the exercise.

Secondly, the training workload quantification allows adapting the training to the racehorse’s needs. Depending on their training level, last race, or current fitness, they do not need to work on the same specificities. For example, some horses may need to work more to maintain their good fitness.

Here is an example of training individualization from one of our clients.

The horse is one of their most successful horses who won several Gr1 races. The team documented every training session that led to his first performance: winning a Gr1 race in October 2020. After a break in training, his performances were not as good as before his great win. Although he was training well, he had not reached the same fitness level as he did before. His recovery data were not good: his 15 mins  recovery was 26 BPM higher than his usual. The team decided to extend the galloping distance and intensity of the training to improve the racehorse’s fitness.

Finally, the data collection allows us to objectively assess the progress achieved over time.

Concrete example – Quantified improvement during training (EQUIMETRE Data)

By analysing the data from Arion I (anonymised for this article), we can see that the training carried out between the two sessions was successful. Indeed, we can note that this racehorse’s recovery has improved thanks to proper training. The data are comparable as the trainings were similar. 

données de tenue de vitesse maximale au cours d'un entraînement

Training of the 04/17/21
Speed = 38 Mph
HR after effort = 118 bpm

données de tenue maximale de vitesse d'un cheval de course après une période d'entraînement

Training of the 04/22/21
Speed = 38 Mph
HR after effort = 107 bpm

Evaluate the impact of a training session

When a horse’s heart rate tends to remain high while the speed has dropped, it means that the training has been too intense and not well supported by the horse. Ideally, the BPM curve should fall directly with the speed curve. If this is the case, the horse is in good physical condition.

cardio cheval de course

However, the heart rate does not only depend on the effort, but also on exogenous factors such as the inclination of the terrain, the weight of the rider, a change in the type or condition of the track, weather conditions, etc.  In order to compare two training sessions, it is important to check that the conditions are as standardised as possible.

Measure the effort intensity with the maximal heart rate

Evaluating a horse’s heart rate allows to personalize its training and to make him work at percentages of his max HR adapted to its capacities. For example, training at 70% of a horse’s maximal heart rate would be an active recovery, which can be effective in improving blood flow and aerobic fitness as well as stamina.

Evaluate the horse’s energy consumption

Conducting a standardized test during a high-intensity training session allows for lactic acid measurement and maximum heart rate. Once performed, the horse’s energy expenditure during exercise is determined using: HRmax, V4 and FC4, V2 and FC2. These precision data provide a complement to the trainer. Indeed, following this test, the knowledge of the different parameters mentioned allows him to evaluate the energy expenditure of his horses during a HIT session with the objective measurement of the heart rate.


Today, high-level athletes surround themselves with health professionals ensuring their health and reducing the risk of injury thanks to physiological data analysis. Racehorses should be no exception. 

Collecting cardiac data quickly and seamlessly is an asset for the racing industry to reduce health risks. For example, longitudinal monitoring and ECG analysis are tools to detect signs of arrhythmia and treat the horse accordingly.

Working with ECG during training

Equine Electrocardiogram – It is a veterinary tool that records the electrical activity of the heart. It allows to investigate and monitor the heart function of the horse by displaying the electrical activity of the heart.

The analysis of the ECG allows several things:

  • The detection of possible heart problems
  • The evaluation of the effects of a treatment during the follow-up of a horse
  • Checking that the heart is working properly
  • Observation of heart rhythm during general anaesthesia
  • Heart rate variability & fitness status measurement  

How to collect an ECG?

it is necessary to have a tool with electrodes and a sensor that records the measurement taken. Over time, the development of ambulatory devices has made it possible to perform ECGs in the box at rest, as well as during exercise for sensors with wireless autonomy (such as EQUIMETRE). The signal can then be stored digitally and transmitted wirelessly via Bluetooth or 3G, allowing live viewing during exercise. 

How to detect respiratory issues?

The racehorse’s respiratory system faces high physiological (high-intensity training) and environmental pressures (such as dust and humidity). These can lead to an inflammation of the respiratory system. By collecting heart rate data during exercise, it is possible to detect early signs of such pathologies.

pathologies respiratoires détectables via EQUIMETRE

We can see that this horse reaches his maximum heart rate as soon as he starts galloping. This is an abnormal situation, all the more so as he is not launched at maximum speed. When analyzing this training, the trainer should ask to consult his veterinarian to investigate the problem.

How to detect cardiac arrhythmias in the racehorses?

The detection of arrhythmias in racehorses meets some challenges in the racing industry: animal welfare, accidents limitation in training and on the racetrack, analysis of underperformance, and detection of hidden pathologies. Whether benign or pathological, these heart rate abnormalities should be investigated to ensure they do not endanger the horse.

Definition – Cardiac arrhythmias are changes in the rhythm of the horse’s heart. They can be abnormal or physiological. They are quite common in highly athletic horses and can become problematic when they disrupt blood circulation and subsequently reduce oxygen supply (through the blood) to the muscles.

fibrillation atrialle

Example of ECG where the horse has atrial fibrillation  (ECG collected by the EQUIMETRE heart rate monitor)

ecg cheval

Example of an ECG where the horse is in good health (ECG collected by the EQUIMETRE heart rate monitor)

Arrhythmias can be dangerous because they can cause major disruptions in the distribution of blood in the vascular network. For example, if the supply of oxygen to the brain is suddenly reduced, the horse may feel dizzy and collapse. The supply can also disturb muscle function when the horse is at full speed, causing him to slow down during work and potentially underperform.

Physiological VS Pathological arrhythmias 

Physiological arrhythmias are frequent in horses. They occur in horses who naturally have a very slow resting heartbeat. The heart occasionally skips a beat in this case.

Pathological arrhythmias occur when disturbances in the heart rhythm randomly happen. Arrhythmias are always pathological when they happen too frequently during the effort.



Heart rate monitor can be used to accurately measure a horse’s heart rate. This is one of the most widely used measuring instruments for sportsmen and women, and allows the heart rate to be recorded to the nearest second.

Arioneo’s heart rate monitor is made up of internationally patented electrodes specifically dedicated to the equine athlete. It enables the heart signal to be collected during the entire effort, even at full speed.

cardio cheval de course




In order to compare horses over time, it is necessary to compare reliable parameters for which training will have an influence. For example, the maximum heart rate only changes very little with training, whereas the physiological adaptation leads to a decrease in heart rate at a given speed (for sub-maximal exercise).

All adaptations of the cardiovascular system are linked and some are shown in the measurement of the heart rate during exercise. Knowledge of the maximum heart rate is essential to quantify the levels of work and recovery specific to each horse. This makes it possible to define the work zones relative to the improvement of specific physiological parameters. In addition, knowledge of characteristic heart rates and recovery times can allow the evaluation of abnormal increases which may be warning signs of an incipient pathology or fatigue.

If you wish to implement connected solutions to collect cardio, speed and locomotion data, don’t hesitate to call on one of our experts!

communication de l'équipe d'un cheval equimetre