Efficacy of High-Intensity Training for Racehorses

An effective training regimen is crucial for all equine athletes. One program used with racehorses, for instance, is high-intensity intermittent training (HIIT), where horses run at near top speed for short periods and then are given rest periods between sprints. How exactly trainers should implement HIIT, however, can be tricky business.

According to the results of a study led by Arno Lindner, DVM, PhD, of the Arbeitsgruppe Pferd in Jülich, Germany, the efficacy of HIIT might depend on the duration of the high-speed sprints, the number of HIIT repetitions throughout the week, and the type of exercise performed on "off" days. The researchers devised an HIIT protocol and examined how the number of workouts per week affected V4 (the velocity at which running under specified conditions yields a blood lactate concentration of 4 millimoles per liter).

"V4 has (long) been used to examine the effect of training," Lindner explained in the study. "Increases in V4 are considered to show a positive effect of training."

The study involved eight 4- and 5-year-old Thoroughbreds that had raced previously, but were not considered to be "race-fit" at the time the study began. Horses were placed into groups and conditioned with HIIT (two 100-meter runs at near-maximal speed with a 10-minute walking period between runs) either once, twice, or three times a week during each of the three six-week conditioning periods. In between HIIT days, horses were worked lightly.

"Horses were subjected to a standardized incremental interval exercise test before beginning a conditioning period (CP), every two weeks during CP, and two weeks thereafter," Lindner said. Shortly after each interval, researchers collected blood samples to determine the horses' blood lactate concentrations.

The researchers determined the HIIT protocol used in this study actually led to a decrease in V4 regardless of how many times a horse was conditioned throughout the week, and they concluded it might not be an effective training regimen for racehorses.

"We assume that the exercise used to condition the horses did not provide for sufficient stimuli (more likely duration of exercise than the speed in this case) to maintain or even increase v4," said Lindner. The team is currently performing more studies to determine if increasing the number of running intervals leads to an increase in V4.

The study, "Effect of Conditioning Horses Once, Twice, or Thrice a Week with High-Intensity Intermittent Exercise on V4," will be published in an upcoming issue of the Journal of Equine Veterinary Science. The abstract is available online.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.