USHJA Study Guide III

Aerobic

Aerobic exercise is characterized by long, slow to moderate, consistent activity that elevates the horse's heart rate to a pre-determined target for a period of time while maintaining adequate oxygenation of muscle tissues. It increases the heart rate and, subsequently, increases the circulation of oxygen through the blood. Aerobic metabolism or production of energy uses oxygen and glycogen to create energy to move muscles41. Over time, aerobic exercise improves the horse's cardiovascular system, increases the horse's ability to oxygenate his tissues and builds endurance. During aerobic exercise, the horse relies on carbohydrates and fats as fuel to generate energy to meet the body's increased demand for oxygen.

Anaerobic II

Anaerobic exercise should not be used until a horse has a base of fitness which has been obtained by aerobic conditioning. Anaerobic exercise is used to prepare muscles for certain functions such as jumping. Skill drills condition certain muscles anaerobically and improve strength, coordination and fluency in those skills.

Anaerobic

Anaerobic means "without oxygen". Anaerobic metabolism produces energy faster but less efficiently than aerobic metabolism42. Anaerobic exercise is brief and intense. It occurs above the aerobic threshold, which means that oxygen in the blood is used more quickly than it is replenished, resulting in the production of lactate or lactic acid. Lactic acid is a toxic waste product that causes a burning sensation and fatigue when it is present in sufficient quantities. During anaerobic exercise, the horse relies on stored energy sources that do not need oxygen in order to be released. Anaerobic exercise involves relatively few repetitions at high levels of resistance for short periods of time (less than 30 seconds). Muscles trained under anaerobic conditions increase in mass, bulk, strength and power, leading to greater performance in short, highly intense activities. Areas most readily affected by anaerobic conditioning include the chest, forearm, hip and thigh muscles. Muscles must rest and recover after anaerobic exercise. The cycle of energy depletion and recovery results in an increase in the mass of fast-twitch muscle fibers. Resistance training can be added to anaerobic exercise in the form of faster gaits and hill work.

Hoof, Bone, Tendon and Ligament Strength and Elasticity

Bone tissue takes the longest to develop to maximum strength. Tendons and ligaments also require a lengthy conditioning time. It takes years to develop bones, tendons and ligaments to peak condition when conditioning a young horse or reconditioning a horse after a lengthy injury. Some concussion is necessary in order to strengthen bone, but extreme concussive forces can cause overloading and damage. Progressive loading to gradually increase the stresses on bone, tendons and ligaments will stimulate these tissues and over time will strengthen them. Bone fatigue occurs when elasticity is lost due to overloading or uneven loading. Methodical, intentional warm-up and cool-down periods before and after exercise are critical to building and maintaining bone and soft tissue condition. When conditioning a horse, it is extremely important to examine the horse's legs every day before and after the training session. In addition, the day after a hard work the horse should be brought out of his stall to be checked for heat, swelling, lameness or injury. These actions help prevent small problems from developing into large ones

Conditioning

Conditioning is a system of bringing a horse to a level of fitness that is sufficient for him to do his job efficiently and correctly. Conditioning horses takes experience and judgment. The level of conditioning for intense physical activity takes an understanding of exercise physiology and modern conditioning methods. A conditioning program should be individualized for each horse. It takes approximately 4 to 6 weeks to bring an unfit horse to the point of regular work.

Signs of overtraining include:

Dull coat, Poor appetite, Weight loss, Lack of energy, Disinterest in work or sourness, Heat and/or filling in the legs

Lung Capacity

During exercise, a horse's consumption of oxygen is 30 times greater than when the horse is at rest. Conditioning improves a horse's aerobic efficiency, both when exercising and when at rest. The horse's ability to take in oxygen and expel carbon dioxide improves, allowing him to go longer distances at faster speeds without becoming winded. At the canter and gallop, the mechanics of the stride cause the horse to breathe one time for each stride. During the first phase of the stride, the hind legs are under the horse, the ribs expand, the gut contents move backward in the abdomen and the diaphragm moves back. These actions create more space in the lungs and make the horse inhale. During the second phase of the stride, the neck is extended and lowered, the rib cage is compressed, the hind legs extend backward and the gut contents move forward pushing against the diaphragm which causes the horse to exhale

General Conditioning III

Intentional systemic conditioning affects virtually all of the horse's systems, allowing the muscles to gain both size and strength. The skeletal muscles are one of the most adaptable tissues in the body. All skeletal muscles are capable of responding to training over time. Muscular conditioning results in improved reflexes, leading to improved muscle coordination and more efficient movement. Because muscles develop more quickly than any other area, beware of mistaking good muscular development as a sign for excellent overall body conditioning. Injuries are likely to occur when a horse's body is overloaded.

General Conditioning II

Muscles are made of fibers. Each fiber contains thousands of threadlike filaments called myofibrils. Muscle fibers are arranged in bundles which in turn make up the muscle belly. There are two types of muscle fibers: Slow-twitch fibers are best suited for aerobic metabolism and fast-twitch fibers are suited for anaerobic metabolism.

Nutrition

Proper nutrition gives a horse fuel for energy and enough liquids to be properly hydrated. A horse doing a larger amount of work will require more food and water.

Heart Strength and Efficiency

Regular cardiovascular conditioning improves a horse's aerobic capacity. Targeted conditioning strengthens the horse's heart, allowing it to work efficiently at a higher rate. It also builds and strengthens capillaries, improving overall circulatory efficiency. The blood carries more oxygen and nutrients. The spleen serves as a reservoir for red blood cells which are released to circulation when the spleen contracts during exercise. This increases the horse's aerobic capacity and gives him endurance

Progressive loading

Small, measured increases in exercise. Too little exercise does not create a demand and stimulate conditioning, while too much leads to overloading, injuries and breakdown. Interval training is based on progressive loading.

Cooling III

Some horses do not sweat, especially in excessive heat and humidity. This condition is known as anhidrosis and can lead to dangerous heat exhaustion. Anhidrosis can be treated with products such as 1 AC. In addition, clenbuterol may be administered by the veterinarian to stimulate the sweat glands. The heat index should be considered when choosing a work level for a horse. Horses work comfortably when the heat index is around 125. At a heat index of 140 the horse relies mostly on sweating to dissipate body heat. At a heat index of greater than 150 (especially if humidity is more than half of this number) evaporative cooling is severely compromised. At 180 there is no natural way for the body to cool itself; internal temperatures will continue to rise, causing heat stress.

Cooling II

The horse also gets rid of heat by radiating it into the cooler air. This does not work when the horse is covered by tack or a cooler, or when the air temperature is hotter than the horse. Horses also may be cooled by convective cooling by the use of fans or breezes. A horse can suffer from heat stress once his body cannot dissipate heat quickly enough through sweating. Heat stress occurs when the body temperature climbs above 105 degrees and usually comes from overexertion rather than the heating effect of the sun's rays.

Rest

The horse requires periods of rest mixed in with the conditioning schedule. Rest allows the replenishment of depleted oxygen and aids in mental stability and attitude. Regular turn out and short training sessions help to keep a horse fresh.

General Conditioning

The horse's body is designed for movement. Skeletal muscles produce locomotion through the process of contracting or shortening. They work in pairs with one muscle flexing a joint and the other extending it. These contractions are caused by a chemical reaction which is triggered by a motor nerve impulse.

Cooling

The primary way that horses cool themselves is evaporative heat loss through sweating. Approximately 70 percent of the heat of locomotion is dispersed this way. A smaller percentage of heat is dissipated by rapid exhalations and panting. Cooling is made less efficient by the insulating effect of the hair coat and the subcutaneous fat layer. Efficient cooling is dependent on circulation and is adversely affected by dehydration. Evaporative cooling starts when the horse sweats by pulling heat from the core of the body. The water vapor on the skin, which is produced by the sweat glands, is evaporated by the outside air. This process can be aided by heat transfer which is achieved by the application of cool water onto the hot surface of the horse's body. The horse's chest, neck and legs should be repeatedly drenched with water. The water should be continuously applied and scraped off until the horse reaches a normal body temperature45. Leaving the water in the coat causes an insulating effect that will make the horse retain heat.

Overloading

This occurs when a body or some part of the body is subjected to work or stress beyond its limits. This may be caused by pushing the muscles too hard and too soon without allowing them the opportunity to strengthen and develop or working at a gait or speed past the horse's current level of conditioning. Overloading may cause a setback or permanent damage. Over training predisposes horses to a compromised immune system, illness and injury.

Training effect

This refers to physical development. All the horse's systems are involved but the cardiovascular system (heart and blood vessels) and the musculoskeletal system (soft tissues and bones) are the two systems that are the most affected.

Peaking

When a horse reaches peak condition he cannot improve his ability or performance. A horse cannot remain in peak condition indefinitely. After peaking, a horse's performance will inevitably decline a bit.

Demand

Work creates a demand for more oxygen and fuel in the cells of the body. The body adapts by increasing the number of red blood cells and improving its efficiency in delivering oxygen and fuel to the cells, removing waste products and producing energy. The purpose of conditioning exercise is to increase demand enough to stimulate a training effect.

The basic principles of conditioning are:

see below