Exertional rhabdomyolysis (ER) is a concern for those who handle horses, especially in the case of performance horses. Rhabdomyolysis is a disease affects the muscles, leading to muscle deterioration often after a period of prolonged exertion or exercise. ER will exhibit a variety of symptoms depending on the severity and the breed. Some horses will present with stiffness in gait, muscle soreness and general poor performance 1. Upon examination muscles will appear swollen and/ or hard. Diagnosis of ER is done through biochemical analysis of creatine kinase and aspartate transaminase levels within blood. These enzymes are shown to be increased during a time of muscle damage. The amount of muscle damage that occurs will vary greatly, and it depends on many factors including underlying medical conditions, age, fitness level, gender and diet 2.
Through a variety of investigative studies involving muscles biopsies, researchers have posed a variety of different pathways through which treatment or prevention could be applied. Certain skeletal muscle gene mutations, found more often in Quarter horses, have explained a potential link between macronutrient balance of diet and risk of developing ER 3.Polysaccharide storage myopathy (PSSM) and Recurrent Exertional Rhabdomyolysis (RER) are both genetic based disease that increase the risk of ER development4. PSSM is characterised by an unusual storage complex of glycogen in the muscles 5. RER is characterised by irregular myocellular calcium cycling and increased muscle contraction and necrosis 4. Current research is investigating the link between these conditions and ER in a variety of breeds. In these cases especially, it has been suggested that nutritional management can be beneficial in preventing and even treating the diseases. Environmental factors such as diet, can affect the phenotypic severity of the conditions4.
In endurance athletes sweating can increase the risk of ER through imbalancing electrolytes and inducing dehydration 6. High energy demands during training will deplete essential nutrient stores in the body, especially the muscles. Deficient levels of vitamin E, selenium, vitamin c, have all be linked to increase risk of damage of ER. By-products produced through muscle break down are toxic to the body and can cause kidney damage as they are exerted through the body 7. Therefore it is essential that endurance athletes be well hydrated after intense exercise, to help flush out potential toxins.
At this point it is not clear if certain nutritional supplements such as antioxidants could protect the body during a period of ER. More research should be done to find the specific mechanism macro and micronutrients play in the development of ER. Although there is no diet that is sure to prevent ER in every horse, following current general nutritional guidelines can maintain health and performance during times of exertion.
Nutritional Prevention of Exertional...