Hormonal changes associated with long distance exercise.

This research study investigates the changes in hormone levels in horses after undertaking an 80 km endurance ride. The study reveals a significant increase in cortisol, noradrenaline, and adrenaline, while a decrease is noted in insulin levels post ride.

Hormone Assay and Findings

• The research consisted of a hormonal examination following an 80 kilometer endurance ride. The hormones that were studied were mainly those related to stress and metabolism – cortisol, glucose, insulin, noradrenaline and adrenaline.
• One of the key findings was the elevation in plasma cortisol levels after the ride in all animals. Cortisol is commonly referred to as a ‘stress hormone’, therefore an increase in its levels indicates a physiological response to the strenuous activity.

Impact on Insulin and Glucose levels

• Interestingly, while glucose levels did not decrease in all of the horses, a marked fall in insulin levels was observed. Insulin is a hormone that helps regulate glucose (sugar) in the blood, and a decrease in insulin might indicate a state of energy conservation in response to the endurance ride.
• The correlation (r=0.89) between post-ride glucose and plasma insulin concentrations suggests a strong relationship between the two. In normal biological function, insulin and glucose are closely linked, and this finding seems to imply that the long-distance ride had affected this balance.

Significant Change in Adrenaline levels

• Finally, the study found that levels of both noradrenaline and adrenaline were significantly elevated after the ride. These are hormones that play a crucial role in preparing the body for a ‘fight or flight’ response, and an increase in their levels might be indicative of the body’s response to the challenging physical activity.
• This study provides valuable insights into how long distance exercise impacts the hormonal balance in horses, and potentially other mammals, offering valuable information for animal welfare and athletic training strategies.