(E05) Association of DFA Alpha 1 with Blood Lactate Measurements in Exercise Tests in Sport Horses

Abstract:

Background: Methods to determine thresholds that separate different exercise intensities often require equipment and the involvement of a veterinarian. Detrended fluctuation analysis (DFA) is a heart rate variability metric that quantifies the degree of correlation within a heart rate series and has been proposed as a non-invasive way of assessing cardiac parasympathetic activity during exercise. The main advantage of DFA is the potential to provide real time or retrospective information under field conditions using rider friendly wearable monitors and its potential association with exercise intensity thresholds and fatigue.

Objectives: The objective of this study was to 1- describe the behavior of the first component of DFA (DFA-α1) during standardized field incremental exercise tests. 2- determine if DFA-α1 is associated with lactate concentrations in this setting. We hypothesized that DFA-α1 would have a high correlation with lactate measurements and that this association would be stronger than the association with heart rate and speed.
Animals: 33 competitive Eventing horses and sport horses without competitive goals

Methods: In vivo observational study that analyzed exercising electrocardiograms obtained in 60 standardized exercise tests in the field.

Results: DFA-α1 was significantly associated with lactate levels (ρ = -0.49, p< 0.001) but the association was weak. A stronger association was observed between lactate and speed (ρ=-0.80, p< 0.001), as well as lactate and heart rate (ρ= 0.74, P< 0.001).

Conclusions: DFA-α1 association with lactate does not support its use as a surrogate of lactate in field incremental standardized tests used for sport horses.