Effect of dietary fats with odd or even numbers of carbon atoms on metabolic response and muscle damage with exercise in Quarter Horse-type horses with type 1 polysaccharide storage myopathy.

The research examines the effects of two kinds of dietary fats on the metabolic response and muscle damage in exercising horses with a specific muscle disease. The study finds that certain types of fats can lead to exercise intolerance and increased damages to muscle in these horses which can be alleviated by feeding long-chain fats.

Methods and Participants

The subjects of the study were 8 horses diagnosed with polysaccharide storage myopathy (PSSM), a muscle disease common in Quarter horse breeds. This disease causes abnormal accumulation of glycogen in the muscles which leads to muscle stiffness, pain and exercise intolerance. The horses were put on isocaloric diets of differing composition for 3 weeks each. The diets used for the research were grain, triheptanoin, corn oil, and high-fat, low-starch feed.

• The grain diet was used to establish a baseline or an exercise target for the study.
• The high-fat, low-starch feed was used as a negative control diet.

The horses performed daily treadmill exercise and had daily blood samples taken. Additionally, muscle specimens and blood samples were taken before and after each exercise test.

Results

After feeding the horses with triheptanoin, they exhibited exercise intolerance, higher plasma creatine kinase activity, and abnormalities in certain substances in the blood. This diet had no effect on the concentrations of glucose in the blood or resting muscle substrates and metabolites.

• Creatine kinase activity is an indicator of muscle damage.
• A rise in certain acylcarnitine concentrations suggests disruptions in energy metabolism.
• An increase in insulin and a decrease in nonesterified fatty acids could be an indication of decreased available energy supply for muscles and increased insulin stimulation of glycogen synthesis.

The grain diet resulted in higher creatine kinase activity, increased insulin concentrations, increased blood glucose concentrations, and more abnormalities in muscle metabolism than were seen with either the corn oil diet or the high-fat, low-starch diet.

Conclusions

The study found that the triheptanoin diet resulted in detrimental effects on the horses, which could be attributed to factors such as decreased availability of nonesterified fatty acids, increased insulin stimulation of glycogen synthesis, and potential inhibition of lipid oxidation. The study concluded suggesting that long-chain fats are among the best dietary options for managing PSSM in horses as they reduced muscle damage indicators.