A biochemical study of the Arab Horse Society’s marathon race.

This study involves a biochemical analysis on horses that participated in a long-distance marathon. Changes in various blood markers, including glucose, potassium, and creatinine were analyzed pre and post-race.

Biochemical analysis

• Blood samples were collected from horses who participated in a 42 km cross-country marathon. The samples were collected before and after the race for comparative analysis.
• The research team observed increased levels of glucose, free fatty acids and glycerol in the blood samples after the race. This suggest an increase in energy metabolism pathways as the race required using stored energy sources.
• They also saw an accompanying rise in plasma cortisol. Cortisol, often termed the “stress hormone”, can increase during strenuous exercise. Increased cortisol and glucagon levels are typically associated with the mobilization of energy stores in response to the physical exertion demanded by the race.

Hormonal changes

• The researchers did note a fall in insulin but it was not statistically significant (P > 0.05). Insulin levels inversely correlate with glucose levels, meaning typically when glucose levels rise, insulin falls, and vice versa. However, the fall in insulin levels after the race was not sufficient to be deemed significant statistically.

Changes in electrolytes and other biomarkers

• Study results also revealed increased concentrations of plasma potassium and albumin, while calcium concentrations dropped. This represents changes in the electrolyte balance of the horses due to the physical exertion from the race. There were no changes noted for the sodium or bicarbonate concentrations, suggesting that only certain electrolyte levels are affected by such physical activity.
• There was an observed increase in plasma urea, creatinine, uric acid, bilirubin and isocitrate dehydrogenase. These chemicals are all markers of muscle activity, and their increase indicates high level of muscle tissue metabolism and possible damage during the race.
• No changes were observed in levels of alkaline phosphatase, another enzyme that can be a marker of muscle activity.

Comparison with non-competitive race

• The outcomes of this cross-country marathon were then compared with an 80 km non-competitive Golden Horseshoe Ride. The comparison was made to further understand and associate changes in blood biochemical markers with competitive as opposed to non-competitive activities in horses.