Estimation of the workload in horses during an eventing competition

The aim of this study was to evaluate workload using suitable parameters related to the physical effort exerted by horses involved in eventing competitions in order to describe the workload intensity and energy demands placed upon such horses. Heart rate (HR), running speed (S), distance covered (Dist), performance duration (D) and blood lactate (Lact) concentrations were measured in horses competing at either the intermediate level (IL) or advanced level (AL) in order to identify workload differences between experience classes. Ten warmblood horses were monitored during an official two-day eventing competition; mean HR (HRmean, bpm), maximum HR (HRmax, bpm), mean S (Smean, m/min), max S (Smax, m/min), D (min) and Dist (m) were assessed during the warm-up and competition phases of each eventing test (dressage, show jumping, cross country). To calculate heart rate recovery (HRR), HR data were collected within the first 3 minutes following the completion of each of the 3 competition phases. Energy expenditure (EE) was estimated using the HR/VO2 relationship. Differences between the groups (AL vs. IL) in HRmean, HRmax, %HRmean, %HRpeak (HR expressed as a percentage of the maximum HR peak obtained during a fast gallop training session), S, D, and Dist were assessed using one-tailed unpaired t-tests for both warmup and competition phases; also differences for EE were evaluated. The relationship between HR and S was also determined for warm-up and competition phases using one-tailed Person's correlations. The relationship between HR decrease during the first 3 min following competition phase completion and recovery time was investigated by multiple nonlinear curve estimation procedures. The results reveal the cross country test to be the most demanding of the eventing competition, requiring significantly greater levels of muscular and energetic effort, in terms of Lact production and EE, with higher values recorded in the AL horses compared to IL horses. The data also show that riders need to optimise warm-up duration and quality in accordance with their competition category. The calculation of HRR is also shown to be an appropriate approach for gauging workload after high-intensity exercise, but not after low-intensity exercise since HRR may be influenced by external factors, like how excited a horse is.