Regardless of the discipline, attaining peak performance is the number one goal for all involved in the preparation of the equine athlete. This Sports Medicine column aims to provide the reader with a greater understanding of how the horse’s body works during exercise. In this first article, the fundamental relationship between nutrition and exercise performance is emphasized. Subsequent articles will include the effects of exercise training, the role diet plays in maximizing the benefits of training, and conditions that impair athletic performance.

Several articles over the past few years have discussed the feeding of horses engaged in high-level athletic activity. The importance of nutrition for optimization of athletic performance (regardless of the level of competition) cannot be overemphasized. Given this intimate link, it seems appropriate that the first article in the new Sports Medicine column delves into the relationship among nutrition, energy metabolism, and exercise performance. Fundamentally, the body’s ability to extract energy from food nutrients and to transfer the energy to the muscles that power the body determines the horse’s (and our) capacity to run and jump. To put it another way, we can view the body as an engine that requires fuel to run, just as the engine of a car requires gasoline to drive its pistons. The fuel tank (the body’s energy stores) is filled by the digestion and absorption of macronutrients (primarily carbohydrates and fats) in the diet. This stored fuel then is used to run the engine (the muscles that provide the power for movement). The faster the engine runs, the greater the amount of fuel required. Conversely, when the fuel runs out, the engine stops running!

The mammalian body uses energy from nutrients provided in the diet to run a multitude of functions, not just muscle contraction during physical activity. For example, energy is required for the digestion, absorption, and storage of food nutrients, as well as for synthesis of new chemical compounds in the body (e.g. protein structures for the building of new tissues). Even more importantly, energy is needed on a continual basis for the maintenance of virtually all of the body’s functions. Nutritionists use the term "basal metabolic rate" to describe the energy used for these maintenance functions.

Although we mostly think of energy needs in terms of physical activity, in reality more than 60% of the body’s daily energy needs relate to this basal metabolism. If these needs are satisfied, the body can use additional available energy for processes such as fuel storage, physical activity, growth of tissues, and lactation. On the other hand, if the energy provided by the diet is barely enough to support basal metabolism, minimal energy will be available for physical activity, and exercise performance will suffer