Muscle issues can easily sidetrack a horse in training. The good news is they don’t have to.
Muscle is by far the largest organ system by weight in your horse’s body. It is highly adaptable and responds to training quicker than other skeletal tissues or the circulatory system. Muscles can also be an underappreciated source of performance problems.
Tying-up (rhabdomyolysis) is the most obvious and serious muscle problem. In this condition, the horse’s muscles begin to spasm while exercising. There are many possible causes, but the bottom line is that it is an energy crisis. After starting to exercise, the muscle has insufficient energy reserves to relax. While it is obvious that energy is needed for muscle to contract and exercise, it is also needed to restore the muscle to a resting state.
Any horse could tie up under the right circumstances. High risk scenarios include electrolyte depletion, overwork, and horses in heavy training that spend one to two days in a stall without exercise. There are also some genetic problems that predispose to tying up – equine polysaccharide storage myopathy/EPSM (primarily drafts and Quarter horses) or malignant hyperthermia (Thoroughbred, Standardbred).
Horses with repeated episodes of tying up should be checked for EPSM or given a trial of medication for malignant hyperthermia. EPSM is treated either by a high fat diet or acetyl-L-carnitine (1 gram/100 lbs of body weight). Horses with only an isolated episode of tying up need careful management to prevent it from happening again.
Common muscle challenges Although not as dramatic as tying-up, nagging muscle pain can be a significant reason for sub-par performance. The most common symptom is high muscle tone at rest. Muscles should not feel hard. They should be yielding to pressure with basically the same consistency as an uncooked steak or beef roast.
HORSES WITH ONLY AN ISOLATED EPISODE OF TYING UP NEED CAREFUL MANAGEMENT TO PREVENT IT FROM HAPPENING AGAIN.
The second most common sign is failure to build muscle mass as expected, or even a loss of muscling. Biochemically, blood chemistry will show an elevation of muscle enzymes like CPK, LDH and SGOT (aka AST). In addition, horses dealing with muscle issues will fail to meet expected milestones in response to training and may develop behavioral issues, including reluctance to work, sensitivity to touch and a “sour” attitude.
These problems originate from the fact that although horses are incredible natural athletes (especially as compared to humans!) what we ask of them is often beyond what they are genetically programmed to perform. Fortunately, many nutritional support pathways can make them better prepared to cope.
Nutritional help for better performance
MSM, methylsulfonylmethane, is a naturally occurring sulfur compound that has been recently proven to have antiinflammatory effects. It reduces muscle soreness and enhances recovery after exercise, including lower levels of muscle enzymes.
Beta alanine is an amino acid that does not get incorporated into proteins but is essential for the production of carnosine in muscle. Research has confirmed that supplemental beta alanine can increase carnosine levels and improve the capacity for work.
Magnesium serves at least two critical functions in muscle. One is to prevent over-excitability – a common symptom of inadequate magnesium is muscle twitching and increased tone. Another is the formation of ATP (the universal storage form of energy in muscle), which cannot occur without magnesium.
Betaine trimethylglycine or TMG results in increased muscle mass and decreased fat mass in people. The mechanism is unclear but the muscle bulking may be due to TMG’s ability to improve water retention. Water is a critical element in allowing muscle to build and maintain stores of glycogen, a source of glucose for muscular work.
Muscles should not feel hard. They should be yielding to pressure, with basically the same consistency as an uncooked steak or beef roast.
Acetyl-L-carnitine is a metabolite that directs glucose into energy pathways rather than storage as glycogen. When supplemented orally, some is also converted to L-carnitine, which is required for transport of fats into the mitochondria of the cells to be burned as an energy source. Equine studies have confirmed supplementation to horses in training is beneficial.
B vitamins are essential for energy generation from carbohydrates, fats and protein.
Muscular issues can easily limit a horse in training, but in most cases, targeted supplementation can make all the difference. Used in regularly worked horses, it’s cheap insurance.