High intensity exercise conditioning increases accumulated oxygen deficit of horses.

The research article investigates how regular, high intensity exercise impacts the aerobic and anaerobic metabolism of horses, ultimately finding that it increases both their maximal aerobic metabolism rate (aerobic capacity) and their maximal anaerobic energy provision (anaerobic capacity).

Objective of the Study

• The study sought to understand the effects of high intensity exercise on both aerobic and anaerobic metabolisms of horses.
• The key question was whether the maximal energy yield of anaerobic metabolism (anaerobic capacity) could be improved through exercise conditioning.

Design and Methodology

• Eight Standardbred horses were subjected to 10 weeks of high intensity exercise (92+/-3 % VO2max) for 4-5 days each week.
• These horses had previously been confined to box stalls for 12 weeks.
• The researchers measured accumulated oxygen deficit, speed at which VO2max was achieved, speed at 115% of VO2max, sprint duration, oxygen demand, oxygen consumption, blood lactate concentration, muscle lactate concentration and muscle glycogen concentrations at different times during and after exercise.

Key Findings

• The conditioning programme resulted in a 17% increase in VO2max and a 27% increase in accumulated oxygen deficit.
• The speed at which VO2max was achieved improved by 11%, and the speed at 115% of VO2max by 9%.
• Oxygen demand and consumption increased by 36% and 38% respectively.
• Sprint duration during high speed exercise test at 115% VO2max increased by 25%.
• While there was no effect of conditioning on blood lactate concentration at the speed producing VO2max, the rate of increase in muscle lactate concentration was greater before conditioning.
• Muscle glycogen concentrations before exercise increased by 17% after conditioning.
• There was no detectable effect of conditioning on muscle buffering capacity.

Conclusions

• Overall, this study demonstrated that a conditioning program that includes regular, high intensity exercise can increase both aerobic and anaerobic capacities in horses.
• Interestingly, increased anaerobic capacity wasn’t reflected in blood lactate concentrations measured during intense, exhaustive exercise or during recovery, suggesting that anaerobic capacity and blood lactate levels may not be direct correlates.