Acid-base variables during incremental exercise in sprint-trained horses fed a high-fat diet.

The study is about the effects of a diet high in fat, combined with sprint training, on several health indicators in horses, including heart rate, blood glucose, and lactate levels.

Methodology

• Seven Arabian horses were put through a standard incremental exercise test on a high-speed treadmill at a 6% slope. Then, the horses were divided randomly into two groups – one was given a control diet consisting of ground hay and concentrates and the other group was given a similar diet but with 10% added fat by weight.
• The horses were then trained with a sprint regimen, 4 days per week. Two additional exercise tests were performed at 5- week intervals.
• Data collected during rest and after each increment of speed included heart rates, rectal temperatures, and samples of venous blood. The blood was analyzed for glucose, lactate, and hemoglobin levels whereas the plasma was analyzed for pH, pCO2, albumin, total protein, and concentrations of sodium, potassium, and chloride.
• Bicarbonate concentration and strong ion difference were calculated, and the total weak acid was estimated from total protein.

Results

• There was an increase in plasma sodium and potassium concentrations, whole blood lactate and glucose, and hemoglobin concentrations during exercise.
• Meanwhile, decreases were observed in plasma pH, bicarbonate, and chloride concentrations.
• The decrease in plasma pH was related to changes in the strong ion difference and total weak acid that worked together to counterbalance a decrease in pCO2.
• Post sprint training, heart rates both at rest and during submaximal exercise decreased, but heart rates at the end of exercise increased. This indicates an improvement in cardiovascular fitness.
• Training also resulted in an increase in work rate and estimated oxygen consumption when the horse heart rate hit 200 beats/min. In addition, the duration of exercise and the speed attained at the end of exercise also increased, suggesting a positive impact of training on horses’ capability for exercise.
• Negative effects were also observed. Training caused an increase in the blood hemoglobin response to exercise but resulted in a decreased pCO2 response.
• Interaction between diet and training was found for pH, pCO2, and strong ion difference. Horses given the high-fat diet registered higher blood glucose during both standard exercise tests and higher lactate concentrations at fatigue during the final test. This suggests that a high-fat diet alongside sprint training may affect glucolysis at the level of pyruvate during an incremental exercise test.

Conclusion

• This study provides insights into how a high-fat diet and sprint training may impact various health indicators in horses such as heart rate, blood glucose, and lactate levels. This could potentially guide strategies for exercise and diet regimes for training horses.