Oxygen consumption and gait variables of Arabian endurance horses measured during a field exercise test.

This research article investigates the respiratory and locomotor characteristics of Arabian horses used in endurance racing. It specifically measures oxygen consumption and gait variations in these horses at race winning speeds to determine their Respiratory Exchange Ratio (RER) and running economy (RE).

Research Objective

The study aims at understanding the aerobic metabolism of Arabian endurance horses during exercise. Using measurements of oxygen consumption and gait variations, the researchers want to estimate the Respiratory Gas Exchange Ratio (RER) and running economy (RE) of these horses under race or field conditions. The RER serves as an indicator for the type of fuel (carbohydrates or fats) that the horses’ bodies use during endurance racing, while the RE shows the cost of transport in terms of oxygen consumption.

Methods Employed

• Five Arabian horses trained for endurance racing were involved in the study.
• The horses were ridden at increasing speeds in the field.
• A GPS logger used by the rider controlled and recorded their speed.
• Each horse had a portable respiratory gas analyser for real-time, breath-by-breath measurements of respiratory variables and the heart rate.
• Data loggers and gait analysis software measured and recorded gait variables.
• Descriptive statistics and linear regression were employed to examine the changes in each variable in response to speed.

Research Findings

• At race-specific speeds (18 km/h), the horses demonstrated a VO(2) of 42 ± 9 ml/min/kg bwt, an RER of 0.96 ± 0.10 and an RE of 134 ± 27 l/km/kg bwt.
• Linear relationships were noticeable between speed and VO(2), heart rate and gait variations.
• Significant correlations existed between VO(2), energy consumption in relation to speed, and gait variations.

Conclusion

The study’s findings suggest that Arabian horses, at winning endurance speeds, primarily use aerobic metabolism based on fat oxidation. Furthermore, the RER seems to be closely connected to the coordination among the running speed, respiratory parameters and gait parameters. This lightens some aspects of the unique physiological capabilities and mechanisms that allow Arabian horses to excel in endurance races.