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Indications of Overtraining in the KFPS 70-Day Test

The KFPS's Central Examination, also known as the 70-day test, is the final stage of the KFPS stallion selection process. The test consists of two phases, the first lasting six weeks and focusing on under-saddle training, while the final four weeks are focused on driving and show driving. The stallions are assessed in all three disciplines, and the results are compiled into a final report used to determine if a young stallion will receive a breeding license. The 70-day test is undoubtedly rigorous, but are adjustments needed for the welfare of the participating stallions? That's precisely what a group of researchers from Utrecht University in the Netherlands set out to determine.

In 2020, researchers followed 16 stallions (average age 3.2 years old) for nine weeks before and during their participation in the 70-day test. The duration and time spent at the walk, trot and canter for all training sessions were measured. Each stallion also performed three ridden standardized exercise tests in weeks 1, 6, and 10 of the test, during which heart rate and plasma lactate concentrations were measured. By the third standardized test, only four of the 16 stallions remained in the study, with the rest excused from the test for various reasons. Here are the study's key findings:

  • Of the 16 stallions, five (31%) were eliminated because of lameness in the first six weeks of the 70-day test.

  • Stallions were trained at the same frequency per week (average 4.7 days) during the 70-day test as they were in the nine-week preparation period; however, training sessions in the 70-day test had a longer duration.

  • The overall duration of training did not change between the three standardized exercise tests, but the focus of training changed between the second and third tests (from riding to driving).

  • During the second and third standardized exercise tests, the stallions' heart rate and plasma lactate concentrations increased compared to the first exercise test, indicating that the stallions were more fatigued.

  • Driving might have a different internal workload than riding, giving extra training load to the horses during the last four weeks of the 70-day test.

  • The training load during the 70-day test increased by 18% compared to the preparation period. This increase, combined with training 4.7 times per week, might have interfered with adequate recovery time.

  • An inappropriate balance between training load and recovery time occurred during the 70-day test.

The researchers concluded that the fitness of the stallions decreased during the 70-day test, suggesting overtraining. Highly intense exercise training over many weeks can result in chronic fatigue called Overtraining Syndrome. Racehorse trainers have long used the terms “overtraining,” “staleness,” or “sourness” to describe a syndrome of poor performance, failure to recover from exercise, and prolonged fatigue that does not resolve for weeks or months. By definition, signs of overtraining syndrome persist after more than two weeks of rest or reduced physical activity. A less severe form of overtraining syndrome is known as “overreaching,” which is also a syndrome of poor performance and fatigue. Athletic recovery from overreaching typically occurs from a few days to two weeks after a reduced workload.

Overtraining is a significant cause of poor athletic performance in both human and equine athletes. In humans, overtraining syndrome has been defined as an imbalance between training and recovery, manifesting as a syndrome of chronic fatigue and poor performance that may be accompanied by physiological and psychological changes. Besides fatigue and reduced performance, behavioral changes such as mood changes and loss of appetite, changes in endocrine function, and weight loss are described in relation to overtraining in humans and horses.

Overtraining is a complex syndrome, and the distinction between non-functional overreaching and overtraining can be difficult to make. The researchers concluded that to optimize training effects and the welfare of the stallions participating in the 70-day test, the workload of the 70-day test needs to be adjusted.

Author's note: The second part of this study assessed adjustments made to the 70-Day Test. Read more about it in our follow-up article:


Siegers, E.; van Wijk, E.; van den Broek, J.; Sloet van Oldruitenborgh-Oosterbaan, M.; Munsters, C. Longitudinal Training and Workload Assessment in Young Friesian Stallions in Relation to Fitness: Part 1. Animals 2023, 13, 689.

McGowan, C., & Whitworth, D. (2008). Overtraining syndrome in horses. Comparative Exercise Physiology,5(2), 57-65. doi:10.1017/S1478061508979202

Munsterman, A. Overtraining Syndrome in Animals. Merck Veterinary Manual. Online. November 2022.

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