Different training methods of endurance horses in the off-season and how this affects aerobic fitness

Abstract: Little is known about how the aerobic capacity of endurance horses responds to retraining, rest, and detraining. In this study, 22 Swedish endurance horses, mainly Arabian horses and Arabian crosses, were followed for 23 weeks during the off-season in the winter. Data collected consisted of resting HR, recovery HR, resting respiratory rate, body condition score and HR in exercise to determine V100 as measurements of aerobic fitness by the means of a standardised exercise test. Horses were divided to have been resting, trained on lower intensity or trained on normal intensity in comparison with training efforts during the competition season. Horses were also divided depending on their prior competition achievements. The aim of the study was to investigate how different training strategies affect the aerobic fitness of endurance horses, in order to get a better understanding how to train and manage the endurance horse for optimal performance. Four horses went through a resting period of 7-14 weeks. After 7 weeks of rest, no changes in aerobic fitness was measured, whereas after a 10-week rest, horses showed a minor decrease in V100. After 14 weeks of rest, one horse showed a 17% decrease in V100 and an increased resting and recovery HR. The horses resting for 7-10 weeks increased in V100 after their resting period and improved with up to 24% from the initial pre-resting measurements. Horses trained at normal intensity showed higher recovery HR at the later stage in the collection period - suggesting potential lowered aerobic capacity after long-term training -, but otherwise horses trained at lower or normal intensity showed no changes in aerobic fitness throughout the project. Horses at higher competition levels had a tendency for lower rest HR, quicker recovery HR and a higher V100. Horses with a body condition score under 4 out of 9 were more prone to a decrease of aerobic fitness. Respiratory values did not change whatsoever during the collection period in any of the horses. Combining previous literature and the findings from this study, it can be concluded that endurance horses can be rested for 6 weeks without losing aerobic fitness, however more research is necessary to draw stronger conclusions on this topic.