My brother is a horse trainer. I called him when I read the article. He says that lactic acids are a bad thing (something to do with horses tying up). Any ways, here is an article I dug up, but I don't have a clue what it means:
Tying-Up
(set fast, azoturia, Monday morning disease, exertional rhabdomyolysis)
Dr J H Stewart BVSc BSc PhD MRCVS
Muscle disorders are a frequent cause of poor performance in horses and 'tying up' is the most common syndrome. Some horses are more susceptible than others. There appears to be a genetic component and a hormonal influence as the condition is more common in fillies. It is also more common in horses that are highly strung.
It is often mistakenly assumed that any horse with muscle pain or cramping after exercise has 'tied-up', and because of this there is a lot of confusion and controversy around the causes, diagnosis, and management of affected horses. Although a number of different muscle conditions produce the same signs, there are basically two types of true 'tying-up':
1. ACUTE STIFFNESS DURING OR AFTER EXERCISE The most common cause is hard exercise that exceeds the horses fitness level. Horses with respiratory viruses and subclinical infections are at increased risk.
2. REPEATED 'TYING-UP' Horses that suffer recurring stiffness after mild exercise, often have a history of poor performance and subclinical cases (reduced performance - but no stiffness or unevenness of gait) can occur.
Horses that 'tie up' repeatedly are referred to as 'chronic'. Chronic tying up is sometimes referred to as Recurrent Exertional Rhabdomyolysis (RER), or Polysaccharide Storage Myopathy (PSSM). One of the misconceptions with tying up has been that it is caused by high muscle lactic acid concentrations. If this was the case all horses would tie up after a race. Polysaccharide storage myopathy is a condition in which there is an accumulation of glycogen (a form of glucose) in muscle tissue. The glycogen that accumulates is abnormal in structure and prevents the horse from using the normal glycogen that is stored in muscle for use during exercise. Affected horses have the classical elevated muscle enzymes on a blood test and to diagnose PSSM requires muscle biopsies.
Polysaccharide Storage Myopathy (PSSM) Recurrent Exertional Rhabdomyolysis (RER)
Researchers have also found that when horses with this form of tying up have episodes of pain, the affected muscles have high levels of calcium trapped inside the muscle cells. Calcium, along with energy (ATP), is required for muscle contraction. To relax, the muscle must remove the calcium from inside its cells. In horses with RER, the process of calcium removal does not operate efficiently. This leads to an accumulation of calcium within the cell which prevents the normal relaxation of the muscle fibres. The muscles remain in a state of partial contraction leading to soreness and muscle damage.
This idea offers an explanation as to why some horses tie up shortly after they begin slow or medium work (ie aerobic exercise). When such horses are excited or under stress, they release increased amounts of the hormones that mobilise energy and stimulate muscular activity. These hormones stimulate the high anaerobic energy system, resulting in increased lactic acid concentrations. Removal of lactic acid from the muscle cells requires a high rate of blood flow, but as these horses are only doing slow to medium work, blood flow to the muscles is only moderately increased. Due to the slow rate of removal of lactate it accumulates within the muscle cells. The high concentration of lactate within the muscles reduces the capacity of the cells to remove calcium and hence their ability to relax.
CLINICAL SIGNS:
* a characteristically painful, shuffling gait
*
severe cases may be unable to move, or even recumbent.
*
pain may cause sweating, elevated heart rate and rapid breathing - these may be the only signs
* blood tests show elevation of the muscle enzymes - creatine kinase (CK) and AST
CAUSES: The classic case is the horse fed high grain and then given a day of rest, hence the name 'Monday morning disease', however ongoing research has shed a lot more light on the syndrome and its complexity.
Tying up can occur in any horse, but there is wide variation in susceptibility to 'triggering' factors.
Factors known to 'trigger' tying up include:
* genetic muscle disorders
* vitamin E and/or selenium deficiency
* hormonal disturbances
* thyroid disorders
* electrolyte imbalances
* diets high in raw grain which can result in carbohydrate overloading
* viral and bacterial infections
* abnormal muscle calcium levels.
http://www.mitavite.com.au/news_VN_B14.asp