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Selection of endurance horses

A good prospect as an Endurance horse will be structurally sound, free moving, well proportioned, well grown, and mentally mature. Many successful Endurance horses are Arabian or Arabian cross-bred horses. Such animals may be more likely to have a higher percentage of aerobic muscle fibers compared with horses bred for sprint or shorter distance racing and as such, would be generally regarded as superior for the sport of endurance (reviewed in Rivero and Piercy, 2008). The type of horse selected may depend on the terrain and climate in which it is expected to perform. Animals racing in the heat and humidity on flatter tracks generally are a leaner body type than those working in cooler climates and over more hilly courses. Some of the differences seen in body type may also be the result of training adaptations.

Most national endurance associations and the Federation Equestre Internationale (FEI) require a system of qualification for Endurance horses to be able to compete over longer distances and at faster speeds. Generally, horses may not start competing in endurance events of 80 km or more until they are at least 5 years old. This allows for optimal opportunity for growth and development. Some horses may have been paddock or pasture raised and are not subject to particular training regimes until they begin training for endurance. Other horses may have been used for showing or other disciplines before being brought into endurance work. Such alternative disciplines may have a benefit in developing the capacity of a horse to cope with novel situations such as mixing with other horses, being examined, and travelling with other horses. Additionally, this training may have helped develop the horse’s muscles such that it can carry a rider in a well-coordinated manner.

Animals raised in a herd situation in paddocks or pastures may have an advantage in that they are accustomed to having other horses around them and have also had the opportunity to develop their musculoskeletal system as they learn to move with confidence over varying terrain. Within a herd, a horse that is assertive and independent, being a natural leader, may often be considered by experts to have the personality to become a strong, competitive Endurance horse.

A thorough prepurchase (veterinary) examination is recommended before purchase to ensure soundness; endurance training is a long-term undertaking and the results can be very disappointing if much time and emotion are spent in training and racing a horse that has underlying structural problems.

Training for distance

The initial training of an Endurance horse should be based on long, slow distance work. It will take several months of foundation training in a new horse that is 4 to 5 years of age. If the horse has not undertaken any formal training before, the time frame for the foundation training will likely need to be extended. Many body systems, including musculoskeletal, cardiovascular (including fluid and electrolyte balance), thermoregulatory, and gastrointestinal systems, need to be trained to cope with the demands of endurance exercise and for the building up of mental strength. Once a horse has been “started,” conditioning for rides over increasing distances will be required; this is, thus, a progressive process.

Getting to know each horse and monitoring its progress are critical factors in training. Although generalizations can be made, each horse needs to be treated as an individual and particular attention should be paid to any problems that may develop, such as back pain, girth rubs, lameness and leg injuries, or mouth rubs from the bit. It is important to ensure that the animal receives appropriate care of hooves because of the impact of hoof function on other aspects of musculoskeletal function. Routine dental care is also essential for optimal performance. Some competition organizers now allow horses to compete unshod. If this is intended, conditioning and care for barefoot riding should commence at the outset of training. If any problems do develop, especially in the early stages of training, work should be stopped while the problem is properly identified and rectified; this may mean that the horse requires further rest until the issue is resolved.

After the horse has been broken in, it may require 2 to 3 months for the animal to get accustomed to being handled and ridden and exposed to all sorts of situations. This usually involves gentle introductory exercise, followed by rest over several weeks, ideally with the horse turned out to pasture for some time. When the horse returns to training, initial retraining exercise is done at a walk and trainers may use walking machines and treadmills as well as riding to develop this fitness. Leading the new horse from another ridden horse may be a useful method to increase the distance travelled without the additional stress of carrying a rider. At this stage, it is very useful to teach the horse patience and control so that it can be ridden, turned, and stopped over all sorts of tracks and terrains. Walking through all types of countryside helps accustom the horse to the different environments it may encounter during endurance events. The horse may have to traverse over and around rocks and fallen timber, trees with overhanging branches and other sorts of vegetation that it has to work through, as well as different surfaces such as sandy, slippery, firm, and rocky areas. A horse that is used to working carefully through all sorts of tracks will develop a good sense of self-preservation and when distance and speed are increased, it is better able to take care of itself and its rider.

Initial walking sessions may be over 5 to 10 km (3–6 miles), three to four times a week, with a few short periods of trotting for several minutes during the session. After 3 to 4 weeks, once the horse has recovered well following an hour or two of continuous exercise, longer rides can be introduced, with 2 to 3 hours of mostly walking and some trotting, perhaps at a pace averaging around 10 kilometers per hour (kph; 6 miles per hour [mph]), for up to 20 km (12 miles) total distance, followed by a rest day. The horse can be walked then trotted in 5-minute blocks and as fitness increases, the blocks of time can be slowly increased. For instance, the time spent trotting should be doubled, and a similar amount of time should be spent walking or until the horse has recovered from the faster pace, which would be evidenced by the return of heart rate (HR) and respiratory rate (RR) to normal. Such workouts can be performed three to four times per week in the initial stages. Most of this work is best done on flat ground, progressing to some hill work, again depending how the horse is responding to the training. Some horses may prefer cantering to trotting, in which case cantering can be substituted for trotting. At this stage of endurance training, the aim should not be competitiveness, but rather, ensuring that the horse is not overworked and has training sessions that are interesting and are not likely to induce lameness. Trotting the horse “in hand” after each training session is good practice for veterinary inspections and very useful for detecting any problems early.

As the horse’s fitness increases and it is able to go further and faster, additional longer sessions can be added per week. The longer sessions can be gradually increased by 5 km (3 miles) each week, progressing up to a total distance of 40 km (25 miles), using walking, trotting and some cantering. As always, the response of the horse to this increase should be monitored closely, to ensure adequate recovery before each session.

According to most endurance race rules, training rides at affiliated events are restricted with regard to the speed the horses can travel, based on the realization that going too fast too early in a horse’s career can cause damage. Training rides are generally 40 km (25 miles) and the horse should be able to cover that distance in 3 to 4 hours. Having a measured training track and progressively increasing the distance travelled in training allow the rider to monitor the progress of the horse, by checking the distance, time travelled, and most importantly, the horse’s response to the exercise. The most useful measure of fitness is HR—at rest, the maximum during exercise, and the recovery after exercise.

Once the horse is able to successfully complete a training ride of 40 km (25 miles) in reasonable time and with good recovery, with some further distance training, it may be ready to attempt an 80 km (50 mile) endurance ride. The horse should be inspected by a veterinarian and be allowed to rest at least every 40 km (25 miles); this gives an opportunity to stop at a shorter distance if the horse is found to be not fit, or sound, or well enough to complete the full ride. To be deemed an Endurance horse, usually the horse must successfully complete a series of longer rides 80 km (50 miles) or more, and these rides may be restricted in pace. Once qualified, the horse will be allowed to attempt longer distances and travel at an unrestricted pace.

Championship rides are 160 km (100 miles), split into sections of no more than 40 km (25 miles), with a veterinary inspection and rest between each section and are run over 24 hours or less. Preparation for a 160 km (100 mile) ride requires much longer training sessions, progressively built over slow long-distance rides. Horses that take 2 to 3 years to be prepared for 160-km rides are much more likely to have a longer endurance career compared with horses that are rushed through their preparation.

Training the musculoskeletal system

Endurance exercise is primarily aerobic and appropriate training will enhance the natural aerobic capacity of muscles (D’Angelis et al., 2005; Essen-Gustavsson et al., 1989; Serrano et al., 2000). Thus, the initial training for the distance mentioned above is also well suited to improve the overall aerobic capacity of muscles (see Chapter 12), as well as associated cardiovascular and respiratory system adaptations.

Such exercise will strengthen ligaments, tendons, and bones, as this base of strength is very important before fast, more intense work is attempted. There will be gradual remodeling of bones and strengthening of tendons and ligaments in response to this conditioning and it is important not to hasten this process. Rest time is critical while the remodeling occurs (see also Chapter 13). If the horse appears listless and tired or demonstrates any signs such as swelling or filling in the legs the day after any training session, it is advisable to reduce the training session or give the horse a rest day, to give the musculoskeletal system time to strengthen and adapt to the stresses being progressively applied.

The growth plates of the vertebrae may not close until the horse is 5 or 6 years old, that is, the back of a younger horse is highly susceptible to injury and remodeling if subjected to intense pressures too early. Working the horse to strengthen the back and abdominal muscles, for instance, using dressage, long reining training, and hill work at different angles can help develop the epaxial musculature or the “top line” of the horse. Good saddle fit is vital and it is important to realize that as the horse grows and develops, the back may change shape so the saddle fit should be checked at least twice a year.

High-intensity training is required for improvements in anaerobic capacity and occasionally within an endurance ride, there may be some anaerobic exercise, for instance, a gallop finish, or hard, fast work up a hill and horses that undergo some short sprint training may be better able to perform under such situations. Short, intense sprints—for instance, cantering fast for 200 to 400 m on the flat ground or for more intensity up a hill—can be undertaken during other training sessions, after a suitable warmup with walking and trotting. The horse can then be walked until it has recovered, with lowering of HR and respiratory rate. Three to four repeats can be conducted within the session.

Training energy systems in the muscle

The aerobic training helps induce the enzyme systems to provide greater muscle aerobic capacity (D’Angelis et al., 2005; Rivero and Piercy, 2008; Serrano et al., 2000), delaying fatigue. Most of these adaptations occur after a couple of months of training and ideally coincide with training to increase the distance the horse travels.

An improved capacity of the muscles to oxidize fat is included in the changes mentioned above. Fat use for energy production has a glucose-sparing effect to delay glycogen depletion and thus increases time to fatigue. Also, increased amounts of fat in the feed increases the amount of fat oxidized by muscles (Harris, 2009). Fat is considered a “cooler” feed because it does not generate the same heat during digestion as does roughage, which is also ideal for Endurance horses. Endurance horses can have fat introduced slowly into their diets, either in various complete feeds or as added vegetable fat. It may take 1 to 3 months for muscles and the digestive system to fully adapt to the supplementation of dietary fat. As the training intensity increases, added fat can be gradually introduced in the diet, which would enhance endurance capacity as well as provide a “cool,” high-density energy source to the horses at a time when their requirements are increasing.

Postexercise replenishment of muscle energy, in the form of glycogen, takes 2 to 3 days (Hodgson et al., 1983; Snow et al., 1982) and therefore, rest and recovery for several days after a hard exercise session or ride are important. This is not possible when the horse is competing in multiday rides and it can be expected that the horse’s performance may be undermined after several successive days of exercise. Fatigue can, in turn, result in poor coordination and stumbling, so added care is required to prevent injury.