The science of deciding on a race strategy for endurance competitions
Dr David Marlin
One of the aspects of endurance that I rarely see articles on concerns how to develop a ride/race strategy. Basically, how are you going to get your horse from start to finish in the best time and or best possible condition. A little understanding of exercise physiology should help you develop better strategies and result in better performance and less tired horses. For more challenging rides this may also help reduce the risk of metabolic issues and maybe even lameness. Of course there are many factors that determine how your horse will cope with a ride: individual athletic ability (determined by genes), shoeing, feeding, training and fitness, health, crewing and even luck. But leaving all these things aside, lets focus on the role that your ride strategy plays. And by ride strategy, here I am talking about not just how fast you ride each loop, but how you ride within each loop.
So let’s start with discussing what the best ride strategy would be. In theory, that’s quite easy. It’s the strategy that gets you from start to finish in the fastest time with your horse in good condition. OK, I accept that’s more a definition. Let’s turn to what is a poor strategy. For me, a poor strategy is one that results either in a tired or even exhausted horse and or a much slower time than a horse is capable of. For example, if a horse completed a ride as shown in Figure 1 below, I would suggest this is a poor strategy. Why? The horse has not been able to maintain the speeds it was asked to do over the first two loops and its presentation times are increasing.
So what are the key factors in developing an appropriate strategy that will allow a horse to perform to its potential in an endurance race and why?
The first issue is to decide at what speed you are going to ride each loop. Actually, that was an intentional “red herring” as it should be at what intensity will you ride each loop. On a flat course with consistent going and similar climatic conditions throughout the ride, speed and intensity are essentially the same thing. So we all understand how to measure speed – GPS watch. But how do we measure intensity? Intensity is reflected by the horses’ heart rate during exercise. Generally, the higher the heart rate the harder (more intense) the horse is working. There are a few things we should be aware of when using heart rate as an indicator or work. It can also be elevated due to excitement, pain, dehydration and increased body temperature. so for a 160km race, the general rule is to keep the heart rate out on course between 130 and 160bpm. Why? Because this is the range in which the horse will be able to obtain a significant amount of energy from stored fat. Above ~160bpm we start to switch to using more and more glycogen. Glycogen is simply stored sugars (carbohydrates) within the muscle and the animal equivalent of starch. Why don’t we want to use glycogen? Well we do and we can. Glycogen allows for faster speeds and acceleration but there is also a limited amount stored in the muscles and most horses are running very low when it comes to loops 4 and 5. In contrast, the body has plenty of fat stores but fat can only be used if the intensity is constant and below ~160bpm.
How you start the race is also crucial to how you will finish. Start with your horse working at heart rates over 160bpm and you will be using up that precious glycogen very quickly. It also takes around 30 minutes of steady exercise for the horses’ body to be able to turn on the energy supply from fat. And if you suddenly decide to have a little gallop half-way around loop 1 to catch someone up after having ridden the first half of the loop carefully, the bad news is it will take another 30 minutes of steady riding below 160bpm to get back to using predominantly fat and saving your precious glycogen for the latter stages of the race. So the key to starting a race is to not ride too hard (above 160bpm) or to ride irregularly.
So to summarise so far, you should start smoothly, you should try to ride at steady effort and at all times keep heart rate below 160bpm.
So what does a steady effort actually look like on course. Well if its a flat course then it means a steady speed. If it’s a course with varying terrain (hills!) then you will be cantering on the flat but possibly dropping back into trot when going uphill to keep the heart rate below 160bpm and then cantering downhill.
Of course you may decide that for a particular race that you are not going to go for a fast time and just want to get round. Its a flat course. Are you better to trot or canter? On the basis of gait efficiency you are actually better to canter than to trot. A horse uses less energy per km in canter than it will in trot. Galloping is not the answer as this is less efficient than cantering. Why is cantering efficient? Because in canter the horse can recover the greatest amount of energy that is stored in the tendons with each stride. Your horse is literally bouncing around the course. Interestingly, the least efficient gait (most energy use per km) is walk!
So how do you decide on your loop 2 speed? Well essentially the same rules apply as for loop 1. Steady pace, heart rate below 160bpm. However, you may also want to take into account your presentation time. If you presented within 5 minutes then carry on. Anything more than 5 minutes you may want to aim for a slightly lower effort (heart rate) on loop 2 e.g. keep closer to 140bpm.
Unfortunately, what we tend to see is patterns like that in Figure 1. Ideally, if you have ridden your horse based on effort and not on speed then you will have a ride pattern similar to that below (Figure 2). Note that the loop “speeds” are expressed as a % of the first loop. The reason for this is that naturally some horses can go faster than others and different courses will represent a different physical challenge. So a horses’ that is very athletic (combination of breed, genetics and fitness) may be travelling at a speed of 25kmh at a heart rate of 160bpm on a flat course whilst a less athletic horse may only be travelling at 15kmh at a heart rate of 160bpm. Where is goes wrong is when the less athletic horse tries to match the more athletic horse for speed. It may work for one or two loops but then it will all fall apart. We see this so often in rides. The more athletic horse may be working at 150bpm but the less athletic horse may be closer to 180bpm. This is just not an effort that can be sustained for more than a loop or so. As a consequence, glycogen is depleted and the horse is reduced to running on fat only and at much slower speeds.
Many riders may have already worked some of this out but just not appreciate the science behind what is going on. However, understanding the science will help you improve your performance and likely have a healthier and happier horse at the end.
So in summary, you should aim to ride at a steady effort and that effort should mean heart rate stays around 120-160bpm, but certainly no higher than 160bpm. Exercise at heart rates above 160bpm uses up glycogen rapidly and glycogen but not fat is the limiting energy store in endurance. Try to ride at a steady effort, slowing for hills, speeding up downhill (if your horse is used to this from training and balanced) and on the flat. Presentation times will usually increase throughout a ride but should not increase dramatically loop to loop. If they are then you need to reduce the effort (heart rate). The key is to ride by effort and not by speed. Effort should dictate speed and not vice versa. Is it really this simple? No. This is just one component. As we said at the start there are many factors that determine success in endurance but probably the most common area in which I see riders making mistakes is in their ride strategy and getting your strategy right by riding to effort as opposed to speed and keeping your effort (but not necessarily speed) constant can make a huge difference in performance terms.