Measurement of maximal oxygen consumption of thoroughbred horses at an altitude of 1250m using open-circuit flow-through calorimetry.

The research article discusses a study that explored the maximum oxygen consumption (VO2max) of Thoroughbred horses in mild hypobaric conditions (1250m altitude), when subjected to a standard exercise test on an inclined treadmill.

Research Objective and Method

• The main aim of this study was to assess the maximal oxygen uptake of Thoroughbred horses at an altitude of 1250 meters.
• To achieve this aim, the researchers utilized an open-circuit flow-through calorimetry method which involved conducting a standard exercise test on a treadmill inclined at a 7% slope. The reason for the incline was to simulate conditions at a higher altitude and test the horses’ physiological response.

Results and Findings

• Oxygen uptake in relation to speed displayed a linear relationship, but only up to a certain exercise intensity. Beyond this level, the relationship plateaued.
• The calculated VO2max values for individual horses under these conditions ranged from 143.5 to 172.6 ml/kg/min. This shows quite significant individual variation amongst the horses tested.
• The relationship between oxygen uptake (VO2) and speed displayed high consistency within and among the horses, with over 99.2% of the total variance being associated with speed.
• At speeds above the VO2max, the oxygen consumption remained constant, implying that the oxygen consumption had reached its maximum and would not increase further irrespective of speed.

Conclusions

• The study concluded that Thoroughbred horses, when subjected to a standard exercise test at an altitude of 1250m on an inclined treadmill, reached a point of maximum oxygen consumption (VO2max).
• Despite the increase in intensity or speed beyond this point, there was no further increase in oxygen consumption. This demonstrates that there is a limit to the amount of oxygen the horses can effectively utilize during high-intensity exercise, regardless of whether the workload increases.