Effects of maintaining different exercise intensities during detraining on aerobic capacity in Thoroughbreds.

The research explored the impact of different exercise intensities during a period of reduced training (detraining) on the cardiopulmonary and oxygen-transport capacities of Thoroughbred racehorses. The study suggests that maintaining an intensity of cantering during detraining may be more beneficial in preserving performance-related variables and oxygen-transport capacity than walking or stall rest.

Study Methodology

• The study involved 27 Thoroughbred racehorses.
• The horses were trained on a treadmill for a duration of 18 weeks.
• After the training period, the horses underwent a detraining period for 12 weeks where they followed one of three exercise regimes – cantering, walking, or stall rest.
• The canter group exercised at 70% of their maximal oxygen consumption for three minutes per day for five days a week.
• The walk group walked for one hour per day for five days a week.
• The stall group went through a period of stall rest.
• Measurements of cardiopulmonary and oxygen-transport variables were made before and after the detraining period.

Results

• After the detraining period of 12 weeks, all groups experienced a decrease in their mass-specific oxygen consumption, maximal cardiac output, and maximal cardiac stroke volume.
• The difference in arterial-mixed-venous oxygen concentration did not decrease in any group after detraining.
• Maximal heart rate decreased in the walk and stall rest groups but not in the canter group.
• Run time to exhaustion and speeds at which various parameters were reached did not change in the canter group, but they decreased in the walk and stall groups.

Conclusion and Clinical Relevance

• The study discovered that horses who maintained an intensity of cantering during the detraining period managed to retain higher performance variables compared to those that followed walking or stall rest regimes.
• This suggests that identifying a minimal threshold exercise intensity during detraining can help maintain performance-related variables and minimize reductions in oxygen-transport capacity.
• This could have useful implications for managing the training and peak performance of racehorses during extended periods of reduced training or ‘detraining’.