In human athletics, undertaking some type of preliminary exercise or warm-up before vigorous exercise generally is regarded as being a beneficial and important part of the overall preparation for training and competition. Although there is often considerable debate regarding the best type of warm-up protocol for different activities, it is widely held that some kind of preliminary exercise can improve subsequent athletic performance and reduce the risk of joint and muscle injury.
Do horses also benefit from warm-up before undertaking more vigorous exercise?
Most trainers and riders do put their charges through some kind of preliminary exercise before training or competition. However, there is little consensus regarding ideal warm-up practices for horses undertaking different athletic disciplines. For example, contrast the warm-up strategies undertaken by Standardbred and Thoroughbred racehorses. Although these horses perform a similar intensity of exercise during racing, there is a substantial difference in pre-race strategy.
Standardbred racehorses often undertake a warm-up of one mile or so at near-racing speed approximately five minutes before the start of a race. In addition, these horses usually receive an initial warm-up 30 to 45 minutes prior to the race. Thoroughbreds, on the other hand, typically undertake a much more limited warm-up before racing.
Which of these strategies provides the best preparation for racing?
It could be argued that the depletion of energy reserves and build-up of lactic acid associated with a heavy warm-up are detrimental to subsequent race performance. Conversely, perhaps a vigorous warm-up regimen is necessary for optimal racing performance.
In this article, we consider the rationale behind warm-up exercise and what is known regarding the effects of warm-up exercise in horses. As is so often the case in the equine world, very little research has been done to determine the merits of different warm-up strategies for horses. Therefore, we also will examine what is known concerning the effects of warm-up in human athletes.
Types of Warm-Up
As the term implies, one of the aims of a warm-up is to increase body temperature. For human athletes, warm-ups fall into one of two main types: passive or active. With passive warm-up, no physical activity takes place--rather, different parts of the body are warmed by the external application of heat. Some examples are applying hot compresses to a specific muscle group or joint, or soaking in a hot tub to warm a larger part of the body. This form of warm-up is thought to be less effective than active warm-up. Passive warm-up also is not very practical for use in horses.
The main benefits of warm-up come from active forms, i.e., the horse performing physical activity. Active warm-up can take two forms--general or task-specific. Typically, a warm-up session will involve both forms, beginning with the general warm-up. This might involve walking, trotting, and light cantering, either under saddle or on the longe line. The aim is to elevate body temperature and heart rate and allow the body to "loosen." For the task-specific warm-up, the goal is to ask the horse to complete some or all of the activities that will be required of him during the training or competition session, albeit at a lower effort level. Some examples are the Standardbred racehorse performing somewhat below full racing speed, the jumper schooling over a few fences, a few sliding stops for a reining horse, or the dressage horse working through a few maneuvers. In that way, the muscle groups to be used during the subsequent period of harder activity (training or competition) are thoroughly prepared.
Potential Physiological Benefits
As mentioned, one of the main effects of a warm-up is an increase in body temperature. The biochemical processes that convert stored energy into the mechanical energy needed for muscle contraction and movement are very inefficient. As a result, a great deal of energy is released as heat, causing a rise in muscle temperature. Ultimately, this heat is distributed throughout the body, and there is an overall increase in body temperature.
The magnitude of the rise in body temperature primarily will depend on the intensity and duration of the warm-up and the environmental conditions. It is important to keep these factors in mind. Muscle temperature normally is about 35ºC (95ºF), but can be lower or higher depending on the climatic conditions. If the horse is exposed to very cold temperatures (winter in the North), it is likely that muscle temperature is somewhat lower. Therefore, it might be necessary to slightly extend the warm-up in cold weather to ensure that muscle and body temperature are within the optimal range.
On the other hand, during hot weather, muscle temperature will be higher. As well, heat loss from the body is slowed compared to cooler conditions. A lighter and shorter warm-up should be undertaken during warm weather--an excessive increase in body temperature could be detrimental to performance during subsequent exercise.
The increase in body temperature resulting from a warm-up has a number of beneficial effects. First, the delivery of oxygen to working muscles is enhanced. Recall that red blood cells are responsible for transporting oxygen in the body--at higher blood temperature, oxygen is more readily released from red blood cells. In the horse, warm-up will also result in the release of red blood cells stored in the spleen, which will also enhance oxygen delivery. Finally, oxygen delivery is increased by greater blood flow in muscles, which results from higher muscle temperature and heart rate, and a redistribution of blood flow to the active muscles.
A rise in body temperature also increases the elasticity of tissues. Muscles contract and relax more efficiently and tendons are more elastic with this rise in temperature, perhaps improving joint flexibility. The enzymes involved in energy-generating processes also work more efficiently at higher body temperature. Therefore, compared to a "cold start," the overall effect of warm-up is to improve efficiency--enhanced oxygen delivery increases reliance on aerobic energy metabolism and, conversely, reduces reliance on anaerobic metabolism, a byproduct of which is lactic acid. A build-up of lactic acid in muscle is one factor that contributes to fatigue during that type of exercise. Reduced reliance on the anaerobic metabolism will decrease lactate accumulation during exercise and delay fatigue, which is particularly important for high-intensity exercise such as racing.
In human athletics, warm-up is considered important for reducing the risk of exercise-related injury. In animal studies, greater forces were required to injure warmed-up muscle and tendon compared to "cold" muscles and tendons. Warming up increases elasticity in these tissues and might therefore reduce the risk of tearing during hard work. It also is suggested that stretching regimens performed during warm-ups help reduce the risk of injury.
However, recent studies in human athletes have indicated that these static stretches have minimal preventive effect on muscle and limb soreness and injury. The greatest benefit probably is gained from the improved tissue elasticity and range of motion resulting from the active warm-up process.
Some human athletes state that a skill-specific warm-up helps them mentally prepare for competition, focusing their minds on the upcoming task. Of course, we have no way of knowing whether a warm-up is equally important for the mental preparation of horses for competition. Nonetheless, most horse owners agree that a warm-up is important for the mental relaxation of the horse.
Horses are creatures of habit--once a warm-up protocol has been established for an individual horse, it would be wise to maintain that routine in preparation for training sessions and competition.
A number of studies have examined the effects of high-intensity warm-up in horses, such as racehorses. No studies have examined the effects of warm-up on lower intensity exercise, such as endurance racing, dressage, reining, or show jumping. None-theless, the results of this research do give us some insight into the value of a warm-up in horses.
Two different studies examined the effect of warm-up on oxygen consumption (VO2) in horses during intense treadmill running (see Tyler et al. 1996; Geor et al. 2000).
As indicated earlier, one of the important effects of warm-up in humans is an increase in the delivery of oxygen to active muscles. If this is also true in horses, we would expect to see a more rapid increase in VO2 (rate of oxygen consumption) at the start of intense exercise and a reduction in the requirement for anaerobic energy.
The study by Tyler and colleagues compared horses which performed either no warm-up or five minutes of trotting before completing a bout of all-out galloping on a treadmill. In the second study (see Geor et al.), horses performed either no warm-up, 10 minutes of a low-intensity warm-up (trotting), or 10 minutes of a higher intensity warm-up (a combination of trotting and galloping) five minutes before intense exercise. In that way, the researchers were able to determine whether the intensity of the warm-up influenced subsequent exercise responses.
Both studies showed that a warm-up does result in a more rapid increase in VO2 during the early part of subsequent intense exercise. However, as there was no difference between low- and high-intensity warm-up, it appears that a light and relatively short (five to 10 minutes) preliminary exercise regimen is sufficient to enhance aerobic metabolism in horses during sprint exercise.
This advantage was well demonstrated in another study that compared the effects of identical low- and high-intensity warm-up protocols on subsequent treadmill running performance (McCutcheon et al. 1999). In that study, the time taken until development of fatigue (an inability to keep pace with the treadmill) was used to assess exercise performance.
Both the low- and high-intensity warm-up resulted in improved exercise performance compared to the no warm-up treatment. This improvement in performance might be explained by the more rapid increase in VO2 during the early part of exercise. As with the previous studies, the amount of energy from aerobic metabolism was higher when sprint exercise was preceded by a warm-up. Conversely, there was a lower proportion of energy derived from anaerobic metabolism and less lactate accumulated in muscle and blood when the horses were warmed up.
Research at the University of Kentucky (Lawrence 1999) also demonstrated that a moderate- to high-intensity warm-up decreases blood lactate accumulation during intense exercise.
The take-home message from this body of research is clear--a warm-up is a very important part of the preparation for high-intensity exercise, such as racing. The resultant enhancement of aerobic metabolism and decrease in lactate accumulation is beneficial to exercise performance.
Other research in horses has shown that a warm-up can be beneficial for body temperature regulation during and after high-intensity exercise (Lund et al. 1996). When horses were warmed up before a four- to five-minute bout of treadmill galloping, the increase in body temperature during exercise was lower compared to the no warm-up protocol, and the horses recovered faster from exercise when given warm-up beforehand. These researchers speculated that the warm-up hastened the onset of sweating, thus enabling the horses to lose a larger amount of heat during intense exercise.
More research is required to determine how warm-up affects the metabolism and performance of horses during lower-intensity exercise. However, common sense and evidence from studies in humans and horses suggests that a warm-up is an important part of every exercise session. Here are a few things to keep in mind when designing a warm-up for your horse.
- For most training sessions, 15 to 20 minutes of preliminary exercise (including an initial period of walking) should provide adequate warm-up. However, you must consider the environmental conditions when planning a warm-up on any given day.
- In warm conditions (e.g., greater than 27ºC or 80°F), the horse will warm up relatively quickly. To avoid an excessive increase in body temperature, shorten the length of the warm-up and/or reduce the intensity. The onset of sweating (wetting of the skin and haircoat on the neck and other areas) provides a useful guide as to the adequacy of warm-up.
- In cold weather, a longer warm-up will be required. In very cold weather, you might consider using an exercise blanket on the horse's back and loins. The insulation from the blanket will hasten warm-up by decreasing heat loss through the skin.
- During training, there should be a seamless transition between the warm-up and the conditioning session. For competition, the warm-up should be timed so that it is completed within five to 10 minutes of the start of the event. Depending on weather conditions, a blanket can be placed on the horse during the interval between the end of the warm-up and the start of competition to keep the horse warm.
- Each warm-up session should include general and activity-specific exercise. Start at the walk, then progressively increase the work intensity. The duration of walking exercise will depend on the individual horse and its housing circumstance. Horses kept indoors most of the day should receive a longer walking period compared to a horse maintained at pasture.
- After five to 10 minutes of trotting/slow canter, the warm-up should proceed to activity-specific exercise. For example, jumpers should be schooled over small fences. When the workout or event will include high-speed galloping, there should be a gradual increase in running speed ending with a very brief period at 60-80% of maximum effort. However, don't overdo this part of the warm-up. Studies in human athletes have shown that excessive warm-up (too long or too intense) can impair subsequent performance.
- Horses prone to the muscle disorder "tying-up" need special consideration when designing a warm-up regimen. In Thoroughbreds prone to repeated episodes of tying-up (recurrent exertional rhabdomyolysis), excitement is a common precipitating factor. Keeping a tight hold during warm-up or the early stages of canter/gallop work can be counter-productive by increasing the level of excitement. Allowing the horse plenty of rein during warm-up might reduce the risk of a tying-up episode.
Warm-Down And Cool Out
Every training session (and following competition exercise) should be followed by a warm-down that includes five to 10 minutes of trotting and a similar period of walking. After hard galloping exercise, the warm-down helps enhance lactate removal from muscle, as well as other adjustments back to the resting state.
It is important for the horse to be "cooled out" properly before completion of the day's activities. In cool weather, the period of walking during the warm-down might be all that is necessary to ensure that the horse is cool. However, during the summer months, it usually is necessary to actively cool the horse (e.g., bathing with cool water). We will specifically deal with this subject in an upcoming article.
Geor, R.J.; McCutcheon, L.J.; Hinchcliff, K.W. Effects of warm-up intensity on kinetics of oxygen consumption and carbon dioxide production during high-intensity exercise in horses. American Journal of Veterinary Research, 61, 638-645, 2000.
Lawrence, L. The benefits of warming up. World Equine Veterinary Review, 4, 6-11, 1999.
Lund, R.J; Guthrie, A.J.; Mostert, H.J.; Travers, C.W.; Nurton, J.P.; Adamson, D.J. Effects of three different warm-up regimens on heat balance and oxygen consumption of Thoroughbred horses. Journal of Applied Physiology, 80, 2190-2197, 1996.
McCutcheon, L.J.; Geor, R.J.; Hinchcliff, K.W. Effects of prior exercise on muscle metabolism during sprint exercise in horses. Journal of Applied Physiology, 87, 1914-1922, 1999.
Safran, M.; Garrett, W.; Seaber, A.; Glisson, R.; Ribbeck, B.The role of warm-up in muscular injury prevention. American Journal of Sports Medicine, 16, 123-129, 1998.
Tyler, C.M.; Hogdson, D.R.; Rose, R.J. Effect of warm-up on energy supply during high-intensity exercise in horses. Equine Veterinary Journal, 28, 117-120, 1996.
About the Author
Ray Geor, BVSc, PhD, Dipl. ACVIM, is professor and chairperson of Large Animal Clinical Sciences at the College of Veterinary Medicine at Michigan State University
POLL: University Equine Hospitals