Hydrotherapy for performance - the use of water for therapeutic benefit in the equine industry - hydrotherapy as a mechanism for enhancing performance in the racehorse
/![Hydrotherapy for performanceGeorgina WhiteWhat is hydrotherapy?The historic use of water for therapeutic benefit in the equine industry has taken a leap in development in recent decades, from the humble use of cold hosing a swollen limb through to the development of water treadmills and water walkers for injury rehabilitation and performance development.Cold hosing and other forms of cooling localized areas of the body is more correctly termed cryotherapy—meaning, it aims to harness the benefits of reduction in temperature to treat mainly acute and edemic injuries. By reducing temperature of the local area, for example, a distal portion of a limb, several key functional changes occur. First, local blood flow is reduced. This is especially useful if an open wound is involved; the precapillary sphincters constrict and direct blood away from the area. Secondly, there is evidence that nociceptors, involved in the perception of pain and sensory receptors located at the end of peripheral nerve endings can be temporarily suppressed with local application of cryotherapy. Following a brief summary of cryotherapy, this article is going to focus on hydrotherapy as a mechanism for enhancing performance in the racehorse, focusing on the specific parameters of fitness that can be targeted and thus improved.Fundamental properties of waterThere are several fundamental principles of water that can be used as a recovery tool to facilitate optimum rehabilitation and ongoing performance improvement. When immersed in water, or made to move through water, the horse’s body, like the human, encounters a medium for which it is not designed, and locomotion is of limited efficiency. It is in fact the imposed limited efficiency that is useful in different training contexts—it forces the body to work harder than on dry ground, thus improving fitness and better preparing the horse’s body for future athletic tests. Similarly, the method of human altitude, or hypoxic training, is where the body will learn to produce the same amount of energy with a significantly lower available amount of oxygen and thus benefit at a later date in a competitive environment.First, and most important in an equine fitness protocol, is the viscosity of the water creating resistance; the resistance offered by water is greater than that experienced in locomotion on dry ground, therefore requiring greater overall effort to move through it. Exercising in water has shown to provide up to 15 times the resistance of exercising on land. This factor alone means that the trainer can achieve a far more challenging training environment without the horse experiencing the concussive forces on the limbs associated with high-end aerobic or anaerobic land based exercise, such as works on a gallops. Resistance also works indirectly at lower water levels whereby horses will choose to step over the water in a bid to avoid resistance. Therapists then utilize this to gain increased flexion at limb joints (further discussion of this throughout the article).Hydrostatic pressure is the pressure exerted on an object when immersed in water. Depth of immersion is an influential factor with greater depth correlating with greater pressure. Depending on the type of hydrotherapy system used, the benefits of hydrostatic pressure will vary. For example, greater hydrostatic pressure will be exerted when using a swimming lane with depths of up to two meters, as opposed to depths of 30-60cm of water on a treadmill. Application of hydrostatic pressure greatly benefits the recovery processes, acting in a similar way as compression bandages. The pressure reduces the formation of edema, or swelling, and improves the elimination of muscular by-products such as lactic acid and carbon dioxide.Buoyancy is not utilized in the same way as it is in humans and small animal hydrotherapy, except in the use of swimming lanes; this is partly due to the obvious size difference and limitations associated with submerging a horse almost completely in water. Buoyancy is achieved when the weight of the fluid displaced by the body is equal, also accounting for the force of gravity on the body. To remain buoyant, the two forces must counterbalance one another. Once this balance occurs, the body is essentially weightless, allowing exercise without the impact of joint load experienced in land-based exercise. These properties act together during water-based exercise to produce the increased benefits to the horse’s fitness discussed in this article.What happens during a hydrotherapy session?Horses are typically introduced to the hydrotherapy equipment to acclimate them and ensure they will be relaxed while exercising. It is important for the horse to establish a relaxed frame when working on the treadmill or in the hydrotherapy pool to prevent any stress-related or compensatory posture during the workout. As we know from land-based exercise, if a horse is stressed, they are likely to tire more quickly; so in order to utilize this workout, acclimation is beneficial.When using a treadmill, it is typical that the horse warms up on a dry treadmill prior to adding water. As with land-based exercise, a thorough warmup ensures adequate preparation of the horse’s muscles to be ready for harder work during the session.The bodily systems during exerciseDuring a hydrotherapy session, the horse’s different bodily systems will be affected in several ways. But essentially, the efficiency and smooth-running of these systems all contribute to overall performance quality, and any deficiencies will act as an overall limitation.The cardiovascular system is often considered to be the horse’s engine during locomotion, working with the respiratory system in concert to provide the horse with the oxygen needed for exercise as well as dispelling by-products. Working as a muscular pump, the heart delivers oxygen and nutrient-rich blood across the body via a network of blood vessels that develops further with long-term consistent exercise. Supplying this oxygen are the nasal structures; as obligate nasal breathers, horses must breathe through their noses. Flaring of nostrils and dilation of the horse’s larynx work to provide a greater cross-sectional area of space for oxygen uptake. When exercise begins, the previously oxygenated muscles begin to work and enter temporary oxygen debt. The cardiovascular and respiratory system combat this by working harder to produce a continual supply of oxygenated blood by increasing the number of breaths taken per minute, thus increasing oxygen intake. During hydrotherapy exercise, the respiratory system will be required to deliver elevated levels of oxygen and removal of increased quantities of carbon dioxide. This is because the horse begins to work towards the higher levels of aerobic exercise. At rest, the horse will be taking in approximately 60 liters of air per minute; when moving towards moderately strenuous exercise, this can increase to as much as 2,250 liters of air per minute.From here the heart increases in beats per minute to keep up with this demand. When still working with oxygen the exercise is considered aerobic; when the horse reaches a speed or exercise intensity where they require greater oxygen than is available, the horse will begin working anaerobically. In a hydrotherapy setting, the treadmill can be considered more the equivalent of strength and conditioning training where heart rate does not rise significantly. On the contrary, swimming increases heart rate significantly without the concussive forces of traditional gallop work. This is when the horse is unable to utilize oxidative processes quickly enough—also known as maximum oxygen consumption (VO2max). Any further energy must be generated by anaerobic glycolysis. The horse cannot sustain long periods of anaerobic exercise, but instead the horse’s aerobic capacity becomes greater and thus delays onset of the anaerobic exercise. Incidentally, horses also experience respiratory locomotor coupling in higher intensity canter and gallop work—a phenomenon that epitomizes the efficiency of the horse as a performance animal. The stride and breath are in sync at a harmonious 1:1 ratio; they must lengthen their stride to increase their speed.From a fitness point of view, the respiratory system is often considered the horse’s limiting factor where minimal conditioning takes place of the related structures. Additionally, the horse’s respiratory system is highly specialized for exercise. This means that any damage to or deficiency of the respiratory system can have significant influence on overall performance. Unlike in the human, the horse’s resting heart rate does not lower with increased fitness; therefore, opportunities to measure fitness are reduced to monitoring during exercise and in the recovery phase. Fitness testing methods may include blood-lactate tests, monitoring of respiratory and exercising heart rate, recovery rate from exercise—with the fitter the horse, the quicker the recovery rate. Like on dry treadmills, the controlled indoor nature of the hydrotherapy environment lends itself well to applying various fitness testing equipment as opposed to some of the environmental constraints often found in-field exercise environments such as out on a gallops.In contrast, to the respiratory system, the horse’s muscular system has great potential for improvement, and targeted use of hydrotherapy can be hugely beneficial. Muscles are arguably the most adaptive structures in the body; consistent and targeted exercise makes them effective energy providers and force producers. As part of muscle development, the individual muscle strands (myofibrils) increase in thickness (diameter) and muscle cell length; increase in muscle cell number is limited to the prenatal and immediate postnatal development. Therefore, muscle growth in the adolescent horse primarily concerns increased thickness of fibers. During exercise, miniscule micro-tears occur that are repaired and result in greater cross-sectional area of muscle mass over time. It is this occurrence that dictates the need for adequate rest and recovery following a period of exercise in order to allow these micro-tears to repair themselves fully.Once the horse has achieved a diet of quality protein and a positive energy balance (i.e., more energy going in than is being used), the horse can begin to build muscle. There is a direct relationship between the range of motion available at a joint and the likely surrounding muscle mass. If the horse has a greater healthy range of motion, then this promotes development of quality muscle or hypertrophy. If the opposite occurs, a horse with a restricted range of motion at a joint, either due to pathology or weakness, lesser work is done at the joint resulting in long-term atrophy of muscle. Using a treadmill in shallow water helps to facilitate this relationship by providing a stimulus to increase range of motion. The horse increases flexion at the hip and elbow joint, for example, to clear 2-3 inches of water and perhaps increases range of motion at the affected joints by 10-20 degrees; when doing this consistently during a session, the 10 degrees increase in range per stride suddenly becomes very influential on work done by muscles.Hydrotherapy as a correctional aidAs well as being used to develop muscle in the generally poorly muscled horse, hydrotherapy has been proven anecdotally to be an excellent method of correcting maladaptive or asymmetrical muscle buildup. This may have occurred following injury or from overuse of one side of the body. There are emerging clinical controlled trials looking at the benefits which are linked at the bottom of this article. Using a treadmill to work the horse in straight lines can be particularly useful where exercise on a circle is contraindicated. As mentioned above, the intricate control that the trainer has, coupled with the ability to view almost every angle of the horse during water treadmill exercise, means that the exercise can be quickly adapted to suit the horse’s capabilities. For example, if the horse is tiring significantly or beginning to compensate, the intensity can be adjusted quickly instead of the horse adopting a maladaptive gait to continue.Unless the distinct biomechanical effects are explained, one may wonder how and why in some cases the small amount of water on the treadmill is beneficial to the horse’s performance and fitness. First, we must consider the proprioceptive influence of water on the horse: Proprioception refers to the horse’s self-awareness and ability to place their limbs correctly; water provides stimulation to this additional sense. By adding just a small amount of water to the treadmill, say around coronet band height, the horse begins to increase the flexion through their limbs to “clear the water” as the air space above the water provides the path of least resistance. With increased flexion comes increased work done by the muscles, in particular the limb flexors. Working this much harder you begin to see the horse really use their body—lowering of the head, engagement of the core musculature, and hindlimbs stepping underneath their barrel. By raising the water further, you are able to increase these benefits to a point. Individual horses will differ, but they will then begin to walk “through” the water rather than stepping over it; here the trainer is then able to utilize the property of resistance further.Aside from the benefits of variation on the horse’s energetic body systems, the horse’s mental state greatly benefits from a change in surroundings. A number of studies as well as anecdotal evidence shows the benefit of variation in a training routine and avoiding mental “burnout” from repetitive training environments.Typical hydrotherapy protocolsThe use of interval training is commonly used in land-based exercise and can also be utilized in the hydrotherapy setting whereby repeated spells of hard work are interspersed with rest or less intense work, allowing the horse to recover to some degree their resting heart rate. Consistent use of this training method conditions the horse’s cardiovascular and muscular systems—over time requiring the horse to recover quicker before commencing the next spell of exercise. When using a water treadmill, spells of high-intensity exercise can either take the form of increased speed or increased water depth; and the trainer can elect to use this in varying forms to suit the trainer’s desired outcomes for the horse. Different centers will work differently, but a typical 10% water fill will reach approximately to the horse’s coronet band, eliciting a proprioceptive response and making the horse reach up and over the water. This is generally considered a height that will begin to tone muscles already present. A 30% treadmill fill will typically reach the fetlock or low cannon bone; here a similar response is seen with increased flexion through the limb joints as the horse steps higher to clear the water. With this, there is greater vertical displacement of the pelvis. Typically you will see an increased rounding of the spine and engagement of the horse’s core musculature. Next you have a 50% fill—generally water reaches the carpus height. This harnesses a different water property in that the horse now moves their limbs through the water, utilizing resistance of the water. A multifaceted, well-rounded hydrotherapy session would typically include short spells at various heights once the horse was well-established working on the treadmill.An example interval session on a water treadmill may take the form of:1-2 minutes dry treadmill warmup; speed generally measured in m/s and adjusted according to the horse’s natural walking speed.1-2 minutes at lowest water height to provide a gentle increase in stimulus and workload done by the horse’s body.Several bursts of work at various lower heights, possibly increasing and decreasing speed accordingly.At the peak or middle of the session, the highest water height for that horse may be selected for a shorter time; this may be where the horse works anaerobically for a period of time depending on fitness.Depending on fitness and desired outcomes, the horse may continue with a couple more spells of lower intensity work before performing a cool down on the dry treadmill.At this time, a trainer may choose to monitor the time taken for the horse’s vital signs to return to pre-exercise levels.A look at the different equipment on the marketMany commercial establishments now offer hydrotherapy sessions for equines with centers offering various services, including swimming pools, water walkers and treadmills. It is important for the therapist or trainer utilizing these to correctly clinically reason their use and apply correct treatment protocol in order to benefit performance and rehabilitation.If the trainer wishes to have a high degree of control over the various parameters available, then a water treadmill would be a suitable choice—with speed, water depth and incline all manageable via a set of controls. This means that bespoke interval training programs are easy to design for targeting specific aspects of each horse’s fitness. On the other hand, a swimming lane also provides a challenging workout for the horse where the trainer can still influence rest breaks between each length repetition without the need of fine tuning the controls; and horses will generally swim at their own pace.When considering if training on a circle or in straight lines is preferable, the trainer has several options. Water walkers will train the horse on a circle with the inside limb taking greater load and the outside limb is required to complete greater ground coverage. On the contrary, both swimming lanes and water treadmills will train the horse in a straight line, which is often considered beneficial in a rehabilitation setting, especially for gait correction, rehabilitation of spinal pathology and straightness training. Training on a circle does have its benefits when applied at the correct time in a rehabilitation program, but as with most training, an adopted ethos of “little and often” is practical. Using a swimming lane for horses that are weak through the back or have previous back pathology would not be ideal given the fact that horses generally swim quite hollow through their backs, keeping their noses up out of the water to breathe. This posture is counterproductive for the horse with back pathology where a rounded, engaged and lengthened spinal posture is beneficial for long-term musculoskeletal health.[insert diagram horse on inclined treadmill with hip in flexion with vertical arrow showing increased flexion required]When it comes to the utilization of buoyancy and hydrostatic pressure, the swimming lane is the most effective method, given that it provides the greatest degree of body submission under water. It will provide the greatest degree of whole-body resistance when compared to the water treadmill, where water depths may not reach above hock height.[insert two images: one of long low posture working in treadmill, one of inverted back posture, ideally skeleton]In summary, having reviewed the physiological effects of exercise in a hydrotherapy application, the use of hydrotherapy should be considered as an adjunct to a horse’s training regimen. It is not limited to use in times of injury but instead as a potentially highly influential additional training method for a trainer’s repertoire.Thanks to Dr. Jessica York for her assistance in the development of this article. Further research studies concerning hydrotherapy can be found below:Kinematics of the equine axial skeleton during aqua-treadmill exercise’ York, 2017Effect of water depth on amount of flexion and extension of joints of the distal aspects of the limbs in healthy horses walking on an underwater treadmill’ Mendez-Angulo et al., 2013Photo ideas:1) a horse on a water treadmill on an incline, ideally taking a forward step with their hindlimb to show the increased hip flexion during incline2) one image of long and low/ horse working over their back on a treadmill in a good posture3) an inverted posture/ skeleton (I will caption with info)4) horse at a stretched/ fast gallop (side view- that can possibly be annotated with the following around the image:-Arytenoir cartilages open-Trachea transports airflow-thoracic cavity loaded-forelimb reaches forward (free flight phase= inhalation)-forelimb strikes ground = exhalation5) horses on a Water Walker](https://images.squarespace-cdn.com/content/v1/517636f8e4b0cb4f8c8697ba/1603539700125-24NC0O8BZE74WRDTNOMF/DSC_7914.jpg)
By Georgie White
What is hydrotherapy?
The historic use of water for therapeutic benefit in the equine industry has taken a leap in development in recent decades, from the humble use of cold hosing a swollen limb through to the development of water treadmills and water walkers for injury rehabilitation and performance development.
Cold hosing and other forms of cooling localized areas of the body is more correctly termed cryotherapy—meaning, it aims to harness the benefits of reduction in temperature to treat mainly acute and edemic injuries. By reducing temperature of the local area, for example, a distal portion of a limb, several key functional changes occur. First, local blood flow is reduced. This is especially useful if an open wound is involved; the precapillary sphincters constrict and direct blood away from the area. Secondly, there is evidence that nociceptors, involved in the perception of pain and sensory receptors located at the end of peripheral nerve endings can be temporarily suppressed with local application of cryotherapy. Following a brief summary of cryotherapy, this article is going to focus on hydrotherapy as a mechanism for enhancing performance in the racehorse, focusing on the specific parameters of fitness that can be targeted and thus improved.
Fundamental properties of water
There are several fundamental principles of water that can be used as a recovery tool to facilitate optimum rehabilitation and ongoing performance improvement. When immersed in water, or made to move through water, the horse’s body, like the human, encounters a medium for which it is not designed, and locomotion is of limited efficiency. It is in fact the imposed limited efficiency that is useful in different training contexts—it forces the body to work harder than on dry ground, thus improving fitness and better preparing the horse’s body for future athletic tests. Similarly, the method of human altitude, or hypoxic training, is where the body will learn to produce the same amount of energy with a significantly lower available amount of oxygen and thus benefit at a later date in a competitive environment.
First, and most important in an equine fitness protocol, is the viscosity of the water creating resistance; the resistance offered by water is greater than that experienced in locomotion on dry ground, therefore requiring greater overall effort to move through it. Exercising in water has shown to provide up to 15 times the resistance of exercising on land. This factor alone means that the trainer can achieve a far more challenging training environment without the horse experiencing the concussive forces on the limbs associated with high-end aerobic or anaerobic land based exercise, such as works on a gallops. Resistance also works indirectly at lower water levels whereby horses will choose to step over the water in a bid to avoid resistance. Therapists then utilize this to gain increased flexion at limb joints (further discussion of this throughout the article).
Hydrostatic pressure is the pressure exerted on an object when immersed in water. Depth of immersion is an influential factor with greater depth correlating with greater pressure. Depending on the type of hydrotherapy system used, the benefits of hydrostatic pressure will vary. For example, greater hydrostatic pressure will be exerted when using a swimming lane with depths of up to two meters, as opposed to depths of 30-60cm of water on a treadmill. Application of hydrostatic pressure greatly benefits the recovery processes, acting in a similar way as compression bandages. The pressure reduces the formation of edema, or swelling, and improves the elimination of muscular by-products such as lactic acid and carbon dioxide.
Buoyancy is not utilized in the same way as it is in humans and small animal hydrotherapy, except in the use of swimming lanes; this is partly due to the obvious size difference and limitations associated with submerging a horse almost completely in water. Buoyancy is achieved when the weight of the fluid displaced by the body is equal, also accounting for the force of gravity on the body. To remain buoyant, the two forces must counterbalance one another. Once this balance occurs, the body is essentially weightless, allowing exercise without the impact of joint load experienced in land-based exercise. These properties act together during water-based exercise to produce the increased benefits to the horse’s fitness discussed in this article.
What happens during a hydrotherapy session?
Horses are typically introduced to the hydrotherapy equipment to acclimate them and ensure they will be relaxed while exercising. It is important for the horse to establish a relaxed frame when working on the treadmill or in the hydrotherapy pool to prevent any stress-related or compensatory posture during the workout. As we know from land-based exercise, if a horse is stressed, they are likely to tire more quickly; so in order to utilize this workout, acclimation is beneficial.
When using a treadmill, it is typical that the horse warms up on a dry treadmill prior to adding water. As with land-based exercise, a thorough warmup ensures adequate preparation of the horse’s muscles to be ready for harder work during the session.
The bodily systems during exercise
During a hydrotherapy session, the horse’s different bodily systems will be affected in several ways. But essentially, the efficiency and smooth-running of these systems all contribute to overall performance quality, and any deficiencies will act as an overall limitation.
The cardiovascular system is often considered to be the horse’s engine during locomotion, working with the respiratory system in concert to provide the horse with the oxygen needed for exercise as well as dispelling by-products. Working as a muscular pump, the heart delivers oxygen and nutrient-rich blood across the body via a network of blood vessels that develops further with long-term consistent exercise. Supplying this oxygen are the nasal structures; as obligate nasal breathers, horses must breathe through their noses. Flaring of nostrils and dilation of the horse’s larynx work to provide a greater cross-sectional area of space for oxygen uptake. When exercise begins, the previously oxygenated muscles begin to work and enter temporary oxygen debt. The cardiovascular and respiratory system combat this by working harder to produce a continual supply of oxygenated blood by increasing the number of breaths taken per minute, thus increasing oxygen intake. During hydrotherapy exercise, the respiratory system will be required to deliver elevated levels of oxygen and removal of increased quantities of carbon dioxide. This is because the horse begins to work towards the higher levels of aerobic exercise. At rest, the horse will be taking in approximately 60 liters of air per minute; when moving towards moderately strenuous exercise, this can increase to as much as 2,250 liters of air per minute.
From here the heart increases in beats per minute to keep up with this demand. …
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