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Lars Roepstorff: “A good surface should give the horse the possibility to perform well and at the same time minimise the risk of injuries”

Tuesday, 08 December 2020

Photo © Hippo Foto/Dirk Caremans Lars Roepstorff at work during Jumping Amsterdam. Photo © Hippo Foto/Dirk Caremans.


Text © World of Showjumping



Lars Roepstorff – professor of equine functional anatomy and a highly experienced veterinary surgeon – is a well-known face to the top riders due to his extensive research on surfaces. During and after constructing a mechanical hoof, Roepstorff and his colleagues was sent by the FEI to the Olympic Games in both London and Rio as well as to the World Equestrian Games in Caen and Tryon to test the properties of the surfaces. Currently, Roepstorff is working intensively with the surface for the Olympic Games in Tokyo. “A good surface should give the horse the possibility to perform well and at the same time minimise the risk of injuries – no matter what discipline or activity you are doing,” Roepstorff says.

Championship surfaces

“It is extremely stimulating to be at a championship and to work with the best in the world. It is true teamwork between those that construct the surface, the ones who are there to maintain the ground, the organisers and of course there is also a lot of communication going on with riders and trainers,” Roepstorff explains. 

Ahead of each international championship, the FEI and the organisers will have a tender procedure where companies from all over the world can send in their offers on delivering the surface for the event. “Afterwards, I and for instance my colleague Oliver Hoberg – that I have been working with a lot – get involved in the process as FEI representatives. We control that the supplier delivers the surface as it was offered, that it is constructed in the right way and also give support in any way needed. We also help optimise the maintenance ahead of and during the competitions,” Roepstorff tells. 

“When it comes to Tokyo, the material was first of all tested in the laboratory – also on its functionality. Furthermore, I have been in Tokyo three times to look at the installation and to further understand how we can maintain this surface in the very best way,” Roepstorff says.

Even if we do everything that we can ahead of the event, there will never be two surfaces that are exactly the same – it depends on the material and the weather.

"Hence, one year ahead of a championship there is often a test event where we look at how much water we need, how deep we should use the harrow and so on. Then I do the measurements and deliver the results to the FEI,” Roepstorff says. 

Even though the measurements are done with five different objective parameters, Roepstorff reveals there is still a subjective side to it. “It is only the horse that really can tell if the surface is good or bad,” he says. “This is why we also include factors from previous experiences as well as feedback from the test event where we take into account what the riders have to say.”

When measuring a surface Roepstorff is focusing on five parameters:

1. Impact firmness

“The first thing we test is the impact firmness, to get to know what the horse feels the first milliseconds the hoof touches the ground. During the first milliseconds of a landing it is only a small part of the body – the hoof – that touches the ground at a high speed which needs to be slowed down,” Roepstorff explains. “It is important that the impact firmness gives good support. It should not be too hard, creating shockwaves in the lower limb, nor too soft so that the hoofs rotate in the surface. Horses are made to move on quite a solid surface. In a landing, you want to see a clear hoof print in the surface – if it is too soft you just get a pit in the sand and if it is too hard you barely see a mark at all. We measure the impact firmness on a scale from 1-5 and want it to be somewhere in the middle.”

2. Cushioning

“The second factor we measure is what we call cushioning,” Roepstorff says. “In this case, we measure what happens when the horses put their whole bodyweight on the limb. When a horse gallops you have 1.5-2 times the bodyweight in peak force on each limb. In a landing it can be up to four times the bodyweight. So, we are talking about a ton or more of pressure on a very small part of the horse. The deeper parts of the surface affect the cushioning the most. You want to have a surface that can carry the weight of the horse and reduce the maximum load without being deep or loose. There are huge differences on the surfaces, depending on how they are constructed and maintained. This is a big challenge for temporary arenas that often are built on concrete." 

If you are on a good grass arena you can measure this pressure 3-4 decimetre underground – that is how far the power is spread out which helps to take the maximum load off the horse. But what do you do with a temporary arena that only has 12-14 centimetre of surface?

"The answer is the absolute right sand, that you mix with both fibre and textile. You then need to maintain the surface perfectly and use the exact amount of water needed. The amount of water is critical in this case. With the fibre and sand mixture and the right amount of water, the maximum load of the horse will not hit straight down in the concrete. Instead the fibre and sand mixture combined with the water will help the power spread to the sides. This you can actually observe if you look closely at the surface around the hoof when the horse is landing: A quite big area, maybe even one square meter around the hoof, is moving. That is the cushioning of the power. If you listen, you can hear the sound of a deep bass drum rather than the clicking sound you get on a hard surface.” 

“The cushioning is where I think we will see the biggest development and improvement of the surfaces in the future,” Roepstorff says. 

3. Responsiveness

“We also measure the responsiveness. The responsiveness is important in the sense that the surface goes back to its original state after a horse has landed. When the next horse enters the ring, the surface has to be exactly the same as for the horses before – throughout the class,” Roepstorff says.

4. Grip

“The fourth issue we check is the grip. The horse’s natural shock absorption mechanics in the first part of the landing is that the hoof slides on the surface. If you look at high-speed movies this will be very clear,” Roepstorff says. “Here we obviously end up in a balancing act between performances and minimising the risk of injuries.” 

“With impact firmness and cushioning it is of course also very important to get a balance where the horse can perform," Roepstorff adds. 

If the ground is hard you can jump higher, however it will be a big load on the horse both in the take-off and landing. The same goes for the grip – you want to have a good grip to be able to ride as fast as possible in the turns, but at the same time you get a bigger load on the hoof since it is not allowed to glide in its natural way.

"So, we are looking for a surface with a bit of glide, but not so much so that the horse will slip,” Roepstorff explains.

“A general problem with training horses is that load is necessary to improve strength and performance. However, loads – either acute overloads or repeated high loads – are the cause of most orthopaedic injuries, acute overload can cause fractures and tendon injuries and repeated high loads tear and wear injuries. So, it is not only a surface-related issue,” Roepstorff adds. 

5. Uniformity

“We also have a fifth parameter and it is the uniformity – that the surface is the same all over the arena,” Roepstorff explains. “It is not like the horses can’t move on different and varied surfaces, because from a biological perspective it is rather the contrary – we should train the horses on different surfaces. However, what’s important with the uniformity is that you can’t see possible differences. If you enter a ring that looks uniform but then you have one turn that is really hard, deep or slippery, the risk of injuries increases dramatically! The reason is that both horses and humans adapt their movement pattern to the surface they are moving on. If the surface suddenly changes, without any warning, the risk of injuries will increase.”

Hoping to get closer to a perfect surface

Since all horses move in various ways and are trained differently, there is no perfect surface Roepstorff says. “There is obviously no ideal surface for all horses and all activities, so when we measure the surfaces, we need to have threshold values for the specific activity. The measurements need to be within the thresholds, and it is always a balancing act between performance and limiting the risk of injuries.”

However, Roepstorff hopes we are getting closer to the perfect surface. “We are constantly trying to develop,” he says. “We have a vision that the more we learn, the more precise we can make the thresholds with the aim to allow good performance while minimising risk of injury. The development of knowledge is not just about the measurements and thresholds, but also about how different surfaces affect the horses and thereby how we can use different surfaces in an optimal way.”

An important aspect to avoid injuries is obviously to train on a similar surface as the one you will compete on, Roepstorff explains.

“If you will run a city marathon on concrete, you can’t just train on soft forest paths. And it is no different for horses.

"Horses can adjust to many different surfaces, but they need to get the chance to do so. In the future my dream is for the organisers to present their surfaces as a for example 2-2,5-3-2,5-4 surface. Then, you as a rider will know what kind of surface to expect and you can train your horse accordingly,” he says.

A huge challenge on all levels

“You will never have the exact same surface on two different show grounds, even though we are working to narrow the limits,” Roepstorff says. “If you have a really good ground at home and you only train on that one, you will be badly prepared to meet the different surfaces in competitions. That’s why you should vary the surfaces: To get the horse prepared for whatever you will meet at the show.”

“At top level competitions, you can see a strive for a surface with a little higher impact firmness and a little more grip to reward performance. However, if you talk with the international riders there are many that don’t like the exact same surface for their training ahead of the championships. Out of a biological perspective this is not ideal, since it will increase the risk of injuries,” Roepstorff explains.

To create a good surface is not just a challenge for the Olympics or the World Equestrian Games, it is difficult at all levels. “Just think about shows with 400-500 starts in a day. Then it is really difficult to have a surface that will stay intact and the same for all horses,” Roepstorff says. 

Are there any potential negatives with today’s high-tech surfaces? “On today’s surfaces you can go full speed throughout the course and the horse will not lose their grip," Roepstorff says. 

To be very general and a bit mean, I would say that today’s surfaces do not reward good riding when it comes to having the horse in balance.

"Thirty years ago, we competed on whatever surface we had and you really needed to know how to ride your horse in balance,” he adds. 

More knowledge needed

“I have been nagging about variation now,” Roepstorff says. “However, there is also a lack of knowledge when it comes to maintaining the surfaces. When we measure the functional qualities, 50% of the value depends on the maintenance – not on the construction itself. Everyone needs to have an interest for, and getting to know, how to maintain their surface. It can save a huge amount of money, since you can use the same surface for longer and also protect your horse from injuries. Try to learn how to take care of the ground in the best way; when to loosen the ground up, when to make it even and to have the right moisture. You have the daily maintenance, but once or twice a year – maybe even more often depending on how many horses that use the ring – you need to renovate the surface. You might need to do a deep harrowing, go over it with a laser, change some of the material or add material. The right maintenance is the most critical point of all.”



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