Methodology and repeatability of a standardised treadmill exercise test for clinical evaluation of fitness in horses.

This paper describes the methodology necessary to perform a clinical exercise test and the expected variability in an individual horse's exercise test measurements based on comparing the results of two repetitions of the test with six horses. The exercise test measurements were obtained with an open flow respiratory gas analysis system, fast time response lactate analyser and an on-board heart rate monitor during an incremental inclined treadmill exercise test. With the exception of peak venous lactate concentration (LACpeak), the results indicate that the mean variability in peak oxygen consumption (VO2peak) peak carbon dioxide production (VCO2peak), peak respiratory exchange ratio (Rpeak), peak heart rate (HRpeak), peak packed cell volume (PCVpeak), peak total plasma protein (TPPpeak) and the maximum number of steps completed during the exercise test (STEPmax) was less than 5 per cent. Variation in the regression analysis of VO2, VCO2 and HR versus velocity was also less than 5 per cent. Slightly higher variation was recorded for LAC and R. Mean variation in the regression analysis of PCV and TPP versus velocity was more than 16 per cent. Mean variation for all of the post exercise test measurements was less than 10 per cent at 1, 5 and 15 mins post exercise. Therefore, the results obtained during a single exercise test are a reliable assessment of a horse's metabolic capability.