# Modelling Energy Demands of Cross-Country Tests in 2-Star to 5-Star Eventing Competitions

## TL;DR

This study creates a model to estimate energy demands in horse eventing competitions, showing how course design and competition format affect horse workload.

## Contribution

A novel model integrating physiological data and course characteristics to estimate energy expenditure in cross-country eventing.

## Key findings

- Course design factors like terrain and speed changes significantly affect energy expenditure in horses.
- Shorter competitions rely more on anaerobic effort, while longer events depend on aerobic work.
- The model explains 29% of variance in power output and 91% with random effects included.

## Abstract

Eventing is an Olympic equestrian sport that includes dressage, cross-country, and show jumping. Among these, the cross-country phase is the most physically demanding for the horse. This study developed a new way to estimate how much energy horses use during the cross-country phase by combining data on their heart rate and blood lactate levels with information about the course, like speed, terrain, and level of difficulty. The model was based on 691 rides from over 256 horses competing at various international levels. It showed that course design, especially hills, changes in speed, and turns, strongly affects how hard horses have to work. The study also found that shorter competitions push horses more into anaerobic (high-intensity) effort, while longer ones rely more on steady aerobic work. This model helps riders, trainers, and veterinarians better understand the demands placed on horses during cross-country, allowing for more tailored fitness training and improved horse welfare.

Eventing is an Olympic equestrian discipline comprising dressage, cross-country, and show jumping, with the cross-country phase imposing the greatest physical demands on horses. This study presents a composite model to estimate energy expenditure during the cross-country phase, integrating physiological data (heart rate-derived VO2 and lactate-based anaerobic estimates) with external workload indicators (GPS-derived speed, elevation, and course complexity). Model development was based on 691 rides from 256 horses across 232 events at 2-star to 5-star competition levels. The analysis showed that terrain, speed variability, and acceleration, largely shaped by course design, significantly affect energy expenditure. Aerobic and anaerobic contributions to power output varied by speed, format, and competition level. The model explained 29% of variance in power output and 91% when accounting for random effects, demonstrating the influence of both external and individual factors. Short-format events exhibited higher anaerobic contributions than long-format events. While the competition level had a modest effect, it reflected increasing technical difficulty and jump size. These findings underline the importance of incorporating both physiological responses and course characteristics in energy assessments. The model supports more targeted conditioning, enhances performance monitoring, and contributes to improved equine welfare by providing a more accurate understanding of workload in cross-country competitions.