Relationship between weight‐carrying capacity and performance in a standardized treadmill exercise test in horses

Weight‐carrying capacity is important in riding horses both for performance and welfare, yet there is no standardized method to estimate individual horses' weight‐carrying capacity. This study investigated the correlation between the physiological response during a (i) standardized incremental exercise test (SET) on a treadmill and a (ii) ridden incremental weight‐carrying exercise test (WET). Sixteen horses (15 ± 3 years) performed both tests, including four steps with increased speed or weight load, respectively. Body weight ratio (BWR) in the WET was 20%, 25%, 30%, and 35% in each step, respectively. Blood samples were collected after each step, and heart rate (HR) was recorded. The velocity (SET) and BWR (WET) at a HR of 180 and 190 bpm and plasma lactate concentration of 2, 3, and 4 mmol/L were estimated. There was a correlation ( r = 0.92, p < 0.05) between the velocity at a plasma lactate concentration of 3 mmol/L (V La3 ) in the SET and the BWR at a HR of 180 bpm (BWR 180 ) in the WET, but no other correlations were found. In conclusion, the SET was not applicable to estimate weight‐carrying capacity in the horse. Further studies should investigate the importance of the correlation between V La3 and BWR 180 .