You can’t improve on Mother Nature when a horse is performing well but many horses struggle to live up to the goals we have for them. The tendency is to focus on lameness and look for sources of pain, which should always be a consideration, but in many horses the overlooked factor is muscle function.
Skeletal muscle makes up 45% of the weight of a horse with a normal body condition score, which is even more than bone. Healthy muscle function is a central component of good performance. In addition to initiating movement, implementing fine motor control of intricate maneuvers and controlling speed, muscle stabilizes and protects the skeleton and joints.
Muscle is a popular target for ergogenic aids – supplements that purport to support good performance. There is no shortage of ingredients with this claim, but only a few that have actually lived up to it.
For efficient energy generation, acetyl-L-carnitine is king. This naturally occurring compound switches the cell away from storing glycogen into burning the glucose used to make it. When converted back to L-carnitine by the body, it is the carrier needed to get fats into the mitochondria to be metabolized for energy.
Muscle is predominantly protein but supporting it requires the correct amino acids. You can’t build muscle just by feeding more protein in general, regardless of that protein’s quality. L-leucine is the most abundant amino acid in muscle and must be present in the diet in adequate amounts as the horse cannot manufacture it (i.e. it is a dietary “essential” amino acid). L-leucine is both present in the structure of muscle proteins and an energy source during exercise. Its metabolite HMB is a potent anabolic stimulus for muscle tissue bulk. L-lysine and L-methionine are two commonly deficient amino acids also needed to build muscle protein.
Glycine betaine – aka betaine for short or TMG (trimethylglycine) – is an amino acid derivative naturally found in plants and especially concentrated in beets. Exercise places high demands on muscle and the body in general. Betaine supplementation has been shown to optimize the following:
- clearance of lactate after exercise
- muscle power and work tolerance
- oxygen consumption
- anabolic response to exercise (muscle definition and bulk)
Do not confuse betaine/TMG with the more widely available DMG. They have different effects.
Last but far from least on our list of desirable supplements for exercising horses and optimal muscle function is beta-alanine. Exercise increases free hydrogen ion levels in muscle, which produces acidosis in the cell. Beta-alanine is an amino acid derivative which increases the muscular cellular levels of carnosine, an important natural buffer of acidity.
Negotiating muscle and performance supplements is a difficult job. Simply feeding the horse more protein won’t get you the results you are after in terms of muscle/topline bulk and definition, muscle energy generation, normal levels of muscle energy stores, glycogen metabolism, comfortable fluid movements and muscle relaxation. To optimize those things you need to focus on ingredients with proven beneficial effects.
Eleanor Kellon, VMD