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Unleashing Horsepower: How Energy Systems Drive Equine Athletic Performance

Fernando J. Marqués, DVM, Diplomate ACVIM, Diplomate ACVSMR

The exceptional athletic abilities of horses can be attributed to several factors, including physiological adaptations, some of which are influenced by training. Muscles, and all cells in the body, require energy to function. Energy from food (carbohydrates, fats, and proteins) is not directly transferred to muscles for biological work. Instead, it is converted into an energy-rich substance known as ATP. The oxidation of carbohydrates, fats, and proteins is the process that produces ATP. There are three main energy systems that supply ATP to the cells: the immediate energy system, the short-term energy system, and the long-term energy system.

The immediate energy system relies on high-energy phosphate sources and plays a crucial role during intense physical activities of short duration that require immediate fuel. These high-energy phosphates are quickly depleted, typically within 20 to 30 seconds of maximum exertion, similar to what happens in humans.

The short-term energy system generates ATP mainly from stored muscle carbohydrates called glycogen. This process does not require oxygen, which is why it is referred to as anaerobic metabolism, leading to lactate accumulation within the muscle cells.

The long-term energy system, or aerobic system, produces ATP during prolonged, intense physical activity. This process requires oxygen, hence the name aerobic metabolism. In this system, fats are a significant fuel source.

The contribution of each energy system and fuel source (carbohydrates, fats, and to a lesser extent proteins) varies depending on factors such as exercise intensity and duration, training status, muscle fiber composition, and oxygen supply to the muscles. Understanding these factors is crucial, as exercise is generally categorized into aerobic/endurance (low intensity over a long duration) and power/strength (high intensity over a short duration). In practice, pure endurance or pure strength activities are rare, and most sports combine elements of both.

Additionally, muscles adapt to specific exercises and sports, which triggers the development of particular muscle fibers that utilize different fuel sources and energy systems to produce ATP.

In equestrian sports, no discipline is exclusively anaerobic or aerobic. Most sports require a combination of both energy systems. For example, racehorses and western performance horses engage in high-intensity, fast-paced activities for short periods, primarily relying on anaerobic metabolism. Conversely, show jumping and polo horses mainly engage in aerobic exercise but switch to anaerobic metabolism to meet the intense energy demands of their sport. Eventing and endurance racing horses, on the other hand, rely predominantly on aerobic metabolism to sustain their energy levels over prolonged periods of activity.

Designing an effective training program for a horse requires considering the optimal adaptation of muscle fiber composition to enhance metabolic function and improve performance in the specific sport.

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