Determination and repeatability of maximum oxygen uptake and other cardiorespiratory measurements in the exercising horse.

The article presents a study that explores the reproducibility of certain cardiorespiratory measurements in horses during exercise, such as maximal oxygen consumption, demonstrating that maximum oxygen uptake shows good reproducibility, while other estimates of aerobic capacity are less precise.

Research Method

• The research was conducted with the help of a rapid incremental treadmill exercise test. This was intended to measure the repeatability of various cardiorespiratory aspects in exercising horses.
• The parameters observed were maximal oxygen consumption (VO2max), maximal heart rate (HRmax), velocity at a heart rate of 200 beats/min (V-200), oxygen consumption at a heart rate of 200 beats/min (VO2-200), oxygen consumption at HRmax (VO2-HRmax), work rate at a heart rate of 200 beats/min (W-200), work rate at HRmax (W-HRmax), and treadmill velocity at HRmax (V-HRmax).
• For the experiment, six Standardbred geldings were subjected to exercise on a treadmill, set at an inclination of 6 degrees, on three different occasions. The exercise protocol involved each horse exercising for 2 minutes at a speed of 3 m/sec, with the treadmill speed increasing by 1 m/sec every 60 seconds until the horse could no longer maintain the pace. The researchers ensured a minimum gap of 24 hours between consecutive tests for each horse.

Findings

• The research did not find any significant differences among the average results of the three tests conducted per horse for any of the eight cardiorespiratory variables measured.
• However, some measurements displayed high variability, with coefficients greater than 10%, including V-HRmax, W-HRmax, and VO2-HRmax.
• On the other hand, variables V-200, W-200, and VO2-200 showcased less variation, indicating a higher level of repeatability.
• Maximal oxygen consumption displayed good reproducibility, with variation coefficients ranging from 1.4 to 9.0%.
• The maximal heart rate of the horses was also highly consistent, as the coefficients of variation for this parameter were 2.7% or less in all cases.

Conclusions

• Based on the findings, the study concludes that the measurement of maximal oxygen consumption has good reproducibility, implying that its measure in horses can reliably reflect a horse’s aerobic capacity.
• However, other estimates of a horse’s maximal aerobic capacity (i.e., VO2-HRmax, W-HRmax, V-HRmax) proved to be less precise and may not provide a consistent measure of the horse’s aerobic capabilities.