Every horse whether they are a companion animal, or a top athlete needs to have a certain level of fitness to perform their required tasks. Fitness is a complex notion which must consider the horse’s musculoskeletal system as well as their cardiovascular health. The horse’s heart, lungs and muscles are all intricate components when assessing fitness, but it is the heart that we can measure, track and evaluate to give us real insight into our horse’s fitness levels.
The heart is often compared to the engine of a sports car. The bigger and more powerful the engine (heart), the faster the car (horse) with the rev counter letting us know how hard the engine is working (heart rate). And although, slightly crude, it is a good analogy.
The horse’s heart rate is the number of times it beats per minute. With each beat, blood is pumped from the heart to the lungs, where it is loaded with oxygen. It then comes back into a different chamber of the heart, where it is pumped back out into the body, and delivers this oxygen to the muscles and tissue so that they can perform. As horses exercise their heart rate increases, as their muscles are demanding more oxygen.
Horses have large hearts, weighing in at around 5kg in a 500kg horse and can pump 30-40 litres of blood each minute at rest. At rest, the adult horse heart rate is typically between 30 – 40 beats per minute (bpm) although a variation of five beats each way is also perfectly normal. It is a good idea to get an idea of what your horse’s resting heart rate is and to get into the habit of regularly checking their resting heart rate. Any changes to normal may be an early indicator that something is going on with your horse. When at rest, the heart rate should not exceed over 50bpm and if it does, veterinary attention should be sought.
Although it is useful to know your horse’s resting heart rate, that figure on its own doesn’t give us much information in the way of fitness. Frustratingly, improving a horse’s fitness doesn’t always lower their resting heart rate, and it is for this reason heart rate monitors are so useful as they tell us what is going on with the heart when the horse is working.
As horses exercise their heart rate increases to accommodate the muscle’s increased requirement for oxygen. The harder a horse is working, the higher the heart rate will be. It is important to remember that ‘working hard’ can take many forms – trotting uphill through sand may be as equally arduous as fast canter work on the flat.
It therefore makes sense that the working heart rates of horses will differ from horse to horse, depending on the type of work they are doing (working in the school vs hill work), the intensity of the work they are doing (trotting vs galloping) and the fitness of the horse – the fitter the horse, the lower the heart rate when doing the same activity compared to a less fit horse.
As a rule, horses’ heart rates generally fall into the following ranges:
Walk: 50-70 bpm
Trot: 70-120 bpm
Canter: 120-185 bpm
Gallop: 185 – 240 bpm
Most ridden work will take place within the aerobic threshold, meaning the horse is using oxygen supported energy pathways to generate energy. This threshold is typically below 160-170 bpm but varies slightly between individuals. If your horse has a working heart rate above 170 bpm and you are not intentionally doing fast, hard work, your horse will be working anaerobically and you should slow down and reduce the intensity of your session.
This leaves us with a window between 100-160 bpm for the majority of exercise to take place, and depending on the speed, intensity and fitness of your horse, your horse’s heart rate should lie within this range. It makes sense that the fitter the horse, the lower the heart rate while working. That’s not to say that very fit horses don’t reach heart rates over 180 bpm, just that the intensity of work to reach this point will be higher than in a less fit horse.
It is worth noting that at the start of exercising we see an ‘overshoot’ of the heart rate, where it appears to rise quickly. This is a response to a release of epinephrine into the blood. This elevated heart rate usually stabilises within two minutes, so it is advised not to monitor heart rate during this time. In particularly excitable horses, they may need to have a thorough warm up before the heart rate reading is truly reliable.
By tracking and monitoring heart rate throughout training sessions we can build up a clear picture of fitness. Training sessions can be compared to track improvements – you should notice that the speed or duration at which you can ride, without pushing the heart rate above the aerobic threshold (around 170-180 bpm) increases as your horse becomes fitter.