Hemorheologic alterations induced by incremental treadmill exercise in thoroughbreds.

The research investigates how incremental treadmill exercise affects the blood characteristics, or ‘hemorheologic’ properties, in thoroughbred horses. It concluded that exercise is associated with significant increases in blood thickness, packed cell volume (PCV) – a measure of the concentration of red blood cells, and plasma solids concentration, along with other changes to red blood cell physiology.

Objective of the Study

• The study aims to understand how the blood characteristics, or hemorheologic properties, of thoroughbred horses get altered due to incremental treadmill exercise. Various parameters like blood viscosity (thickness), PCV, RBC filterability, density, shape, serum and RBC electrolyte concentrations, plasma total solids and lactate concentrations were measured at different stages of the exercise.

Procedure and Measurements

• The research was conducted on five thoroughbreds. The measurements were attained before exercise, at treadmill speeds of 9 and 13 m/s, and 10 minutes post-exercise.
• The PCV level or the concentration of red blood cells in the blood, the blood’s thickness or viscosity, and plasma total solids concentration noticeably increased during the exercise.

Effects on Blood Viscosity and RBC Filterability

• Even after controlling the PCV to 40% by adding or removing each horse’s own plasma, the blood viscosity remained significantly greater in the sample obtained at 13 m/s, compared to the samples taken at rest.
• The filterability of RBC was significantly reduced at 13 m/s, compared with values from other sampling times.

Changes in RBC Density and Size

• During exercise, a considerably larger proportion of the red blood cells were found to be less dense and were located in the upper layers of the RBC density gradient profile, compared to the resting values. This change was associated with a visible increase in RBC mean cell volume.

Effect on Electrolytes

• Quick increases in serum sodium and potassium concentrations during exercise were observed alongside significant increases in RBC potassium and chloride concentrations.

Conclusion

• The study showed a consistent pattern of changes to the blood properties associated with exercise in thoroughbreds, suggesting that multiple blood tests are necessary to adequately define these complex changes during exercise in horses.