By Mark Andrews

It would be better to base heart rate recovery tests in endurance competitions on each individual horse’s resting heart rate, according to the authors of a recent study.

Veterinary check points (vet gates) are set up at various points along the route of an endurance race, to ensure that each horse is fit to continue the competition. 

Horses are held at the vet gate and checked for heart rate recovery, metabolic status, gait, and general condition. The heart rate must have fallen below a specified value before the horse can continue. The required heart rate is the same for all competitors.

It has been assumed that horses with low resting heart rates would reach the required limit for continuing more quickly. Now research by Arno Lindner and colleagues has shown that is, indeed, the case.

The study was performed at the Veterinary Science Faculty’s Centre for Physiology and Pathophysiology of Sport Horses at the National University of La Plata, Buenos Aires, Argentina. A full report of the work has been published in the journal Animals.

Seven horses were involved in the study, in which they were exercised at different speeds for up to 60 minutes on a treadmill.

The researchers examined the relationship between resting heart rate (HRresting) and HR after exercise (HRrecovery), measuring heart rate before exercise and on several occasions during the 30 minutes after the end of exercise. 

They found a positive relationship between HRresting and HRrecovery, supporting the view that the time taken to reach the pre-defined HR is shorter when the resting HR of a horse is lower.

The study also found that a lower resting HR was not associated with higher endurance capacity. The research team looked at the relationship between HR and V4. (V4, the velocity at which the blood lactate concentration is 4 mmol/L, is widely used to assess athletic performance.)

With only a few exceptions, there were no significant relationships between the V4 of the horses and their HRresting or between V4 and HRrecovery.

The authors suggest that, based on their findings, it would be much better to determine the individual HRrecovery during the initial veterinary examination of a horse to decide if it was fit to compete, and apply this value at the vet gates during the competition.

Printed with permission of Mark Andrews, Equine Science Update.

This article was originally published in the Early Summer 2020 issue of Canadian Horse Journal

Photo: Shutterstock/Kertu