Endurance: What to Feed

Ever wondered how your endurance horse converts last night's dinner into today's performance? This is how he does it.

The horse's body converts feed into energy storage molecules (glycogen, glucose and free fatty acids). During exercise, a horse's muscles need ATP (adenosine triphosphate), in order to contract . There are two processes in the horse's body, which produce ATP from these storage molecules:

Aerobic metabolism
Anaerobic metabolism

When the horse is working at a moderate pace (usually up to trotting speed in a fit endurance horse), the aerobic pathway produces ATP for muscle contraction from glycogen, glucose and fatty acids. It uses oxygen which has been carried to the site of action by the blood. Harmless by-products are produced, which are excreted as the horse sweats.

When the horse needs to expend more energy than this by, for example, climbing a hill or producing a burst of speed, anaerobic metabolism takes over. Anaerobic metabolism doesn't need oxygen and produces energy very fast, but in small amounts. The big disadvantage of the anaerobic pathway is the production of a by-product called lactic acid, which builds up in the muscle, causing the pH of the muscle to drop producing fatigue and possibly contributing to the "tying up" syndrome. When a certain level of lactic acid in the muscle is reached, the pathway shuts down. Then, the fast muscle action cannot be maintained.

Most of the time, the endurance horse travels at speeds which can be fuelled by the aerobic pathway. If fit, the anaerobic pathway should only be used for short intervals. So fatigue in endurance horses is more likely to result from the glycogen stores running out than from lactic acid build up. Eventually however, the horses heart rate increases, the rate of ATP utilization increases, and the "anaerobic threshold" is reached. This usually happens at about 140-150 beats per minute. At this stage, fatigue starts to set in.

Adequate starch and fat must be provided in the diet of the endurance horse. Starch is very important, as it is one of the major factors in the synthesis of glycogen. Increased feeding of fats has recently been shown to have a glycogen sparing effect. This means that a larger proportion of fatty acids are used in the aerobic pathway, thus increasing the amount of time before the glycogen runs out. So, it would be a good thing to supplement the endurance horse's diet with up to one cup of sunflower oil per day.

Protein, although essential in the diet and useful in many ways, should not be fed in excess. This is because it is not an efficient energy source, it results in a need for increased water and potentially harmful breakdown products such as urea and nitrogen are produced.

One of the most important energy sources for the horse is fibre (provided by hay or grass). The horse's hind gut is full of bacteria that ferment fibre. The fermentation process produces energy for a long time after the meal, making this a valuable source of energy for the horse during the ride.

Besides these there are nutrients that are missing in feed normally provided to the endurance horse. So it is always wise to feed a good supplement which provides these nutrients. A feed supplement designed for endurance horses should:

- help to delay the "anaerobic threshold", thus prolonging the period of harmless aerobic ATP generation and delaying the onset of muscle fatigue.
- help to increase the stores of glycogen so that the store doesn't run out during exercise
- help to increase the oxygen-carrying capacity of the blood, so that sufficient oxygen is available for the aerobic pathway
- manage the situation of lactic acid build up and the resulting problems such as muscle fatigue, recovery, stiffness and "tying-up"

Some of the nutraceuticals that are believed to have these effects are:

- Thiamine (been found to decrease the lactic acid levels)
- Cyanocobalamine (could improve propionate conversion to glucose)
- Vitamin E (A study has found that vitamin E deficient horses show a quicker fatigue time during endurance exercise)
- Folic acid (Involved in the synthesis of haemoglobin, the blood's oxygen carrier)
- Siberian Ginseng (A proven adaptogen with a glycogen sparing and ergogenic (endurance-enhancing) action)
- Spirulina (Energy producing)
- N,N-dimethylglycine (Aids recovery, ergogenic)
- MSM (Helps recovery by decreasing stiffness and inflammation)
- Selenium (Known to be effective in decreasing "tying-up" or azoturia)

Ginseng, the Power Herb

Ginseng is a herb that has been attributed many, many powers. Many years ago, wars were fought defending ginseng lands. These days, products still line the shelves of pharmacies, promising all sorts of things - from virility to improved brain power. Some of these claims have been scientifically substantiated, others - well, they are just claims, and scientific proof is still lacking.

Types

I was surprised at the number of different plants that go under the name of ginseng. Most ginsengs are Panax ginsengs - this includes the American ginseng, Korean ginseng and Himalayan ginseng. These are very rare and hence expensive. Siberian ginseng belongs to the same family, but is a different genus - Eleutherococcus.

History

The use of ginseng dates back to prehistoric China. The Chinese noticed that the root was shaped like a man and believed it to be a symbol of human health, promoting long life, wisdom and fertility. It soon became hugely popular. Wars broke out over ginseng lands and smuggling of the root was punishable by death.

Much later, interest in western countries was stimulated after Soviet scientists used Eleutherococcus as stress medication for cosmonauts.

Action

The following actions have been attributed to ginseng:
anti-depressive
physical and mental performance enhancer
resistance stimulation

Research

Soviet scientists were the first to investigate ginseng. It became classified as an important adaptogen (a substance which improves the body's ability to adapt to stressful situations). They showed that Siberian ginseng improves mental and physical performance under stressful conditions. In athletic events, ginseng shifts the metabolism to favour the utilisation of fat over carbohydrates for energy. This delays lactic acid build-up. Which, as any athlete will tell you, is a good thing, as lactic acid causes muscle fatigue and cramps.

Ginseng has also been shown to have immunostimulatory activity. In other words, it fights pathogens (disease-causing entities). Ginseng does this by increasing the number of white blood cells (fighting cells) and by helping with antibody formation.

Ginseng has also recently been found to be useful in the treatment of Type II diabetes in humans.

The Nutraceutical Alliance in Canada has been specifically researching ginseng in horses. They have found evidence that substantiates both the fatigue reducing and the immunostimulatory effects of ginseng.

Use

Ginseng has withstood toxicity tests, with no known side-effects except occasional cases of insomnia in humans, when taken too close to bedtime. There are also no known interactions with other drugs.

Very high doses should be avoided, however, as they can result in high blood pressure. The dose depends on the form of ginseng used. For the dry powdered root, not more than 6 grams should be taken daily.

The potential for the use of ginseng in horses is enormous. Our horses are constantly coming into contact with other horses and places, and as a result are being exposed to a wide variety of nasty foreign pathogens. The immuno-stimulatory properties of ginseng could be put to good use in helping the horse fight these pathogens.

As for the fatigue reducing effect of ginseng, the advantages are obvious - more stamina, better recovery, less muscle fatigue, more energy.