Blood chemistry and skeletal muscle metabolic responses during and after different speeds and durations of trotting.

This research article investigates the effects of different speeds and durations of trotting on the blood chemistry and muscle metabolism of eight standardbred horses. Focus is put on specific biochemical parameters such as free fatty acids, glucose, creatinine, cortisol concentrations and more.

Study Design and Methodology

• The study included eight standardbred horses that were made to trot on a treadmill.
• The horses trotted for 55 minutes at a sub-maximal speed of 5m/sec before performing an exercise test that involved 2-minute intervals at increasing speed.
• The researchers collected heart (HR) and respiratory rates (Rf), as well as venous blood samples, not only during the exercise but also before and 5 minutes after it. In addition, muscle biopsies from the gluteus medius and rectal temperatures were taken before and after the exercise.

Results and Findings

• The average HR was 132/min and the average Rf was 156/min during the 5m/sec trotting.
• The researchers observed significant increases in plasma free fatty acids (FFA), glucose, creatinine, and cortisol concentrations with the 5m/sec exercise.
• Blood lactate displayed a slight increase. Plasma potassium initially rose and then fell as the duration of trotting increased.
• Five minutes after exercise, plasma FFA, glucose and cortisol concentrations continued their rise, while creatinine and lactate levels declined slightly. Potassium concentrations fell rapidly to values below resting levels.
• The mean intramuscular (im) glycogen utilization was 86 mmol/kg, and no significant changes were seen in creatine phosphate (CP), adenosine triphosphate (ATP), and glucose-6-phosphate (G-6-P) concentrations. Muscle lactate showed a significant decrease.
• During the second exercise test, the mean HR rose to 215/min and Rf to 126/min at top speed. Plasma glucose did not undergo any significant change, while lactate, ammonia, and potassium concentrations increased to a greater extent.
• Following exercise, these parameters continued to increase except for creatinine, which declined slightly, and potassium, which dropped rapidly. The mean im glycogen utilization was 144 mmol/kg, ATP concentrations remained the same, CP declined, lactate and G-6-P increased during exercise.

Implications of the Findings

• The findings of the study point to the varying effects that different speeds and durations of trotting can have on horses’ blood chemistry and muscle metabolism.
• This is valuable information for trainers, veterinary practitioners, and scholars interested in the physiological responses of horses to different exercise intensities and durations and can help optimize training regimens for performance horses.