Variations in lactate during a graded exercise test due to sampling location and method

Infrared Thermography Correlates with Lactate Concentration in Blood during Race Training in Horses

In horse racing the most acceptable way to objectively evaluate adaptation to increased exertion is to measure lactate blood concentration. However, this may be stressful for the horse, therefore, a simple, noninvasive procedure to monitor race progress is desirable. Forty Thoroughbreds attended race training, with blood samples collected at rest, immediately after, and 30 min after exercise. The lactate concentration was determined 60 s after blood collection using an Accusport®. Thermal imaging of the neck and trunk areas was performed following international veterinary standards from a distance of approximately 2 m from the horse using the same protocol as the blood sampling. The Spearman rank correlation coefficients (ρ) between the changes in the blood lactate concentration and surface temperature measures were found for the regions of interest. The highest positive correlation coefficients were found in the musculus trapezius pars thoracica region for the maximal temperature (T Max; ρ = 0.83; p < 0.0001), the minimal temperature (T Min; ρ = 0.83; p < 0.0001), and the average temperature (T Aver; ρ = 0.85; p < 0.0001) 30 min after the exercise. The results showed that infrared thermography may supplement blood measurements to evaluate adaptation to increased workload during race training, however, more research and references values are needed.

Exercise testing in Warmblood sport horses under field conditions

Regular exercise testing in Warmblood sport horses may, as in racing, potentially help to characterise fitness indices in different disciplines and at various competition levels and assist in understanding when a horse is 'fit to compete'. In this review an overview is given of the current state of the art of exercise testing in the Olympic disciplines of eventing, show jumping and dressage, and areas for further development are defined. In event horses, a simple four-step incremental exercise test measuring heart rate (HR), lactate concentration (LA) and velocity (V) is most often used. In dressage and riding horses, a wide variety of exercise tests have been developed, including incremental exercise tests, indoor riding tests and lunging tests. In show jumping, the use of a five-step incremental exercise test and exercise tests evaluating technical skills and fatigue of the horse has been reported. The velocity at a plasma LA of 4 mmol/L (VLA4) and HR recovery during submaximal exercise intensity have been shown to be the best parameters in event horses for predicting performance and impending injuries. In riding horses, the fitness level of horses is also an important determinant of injuries. Implementation of regular exercise testing and monitoring of training sessions may have important added value in the assessment of performance ability and potential future injuries in Warmblood sport horses. However, there is an urgent need to standardise methodologies and outcome parameters in order to make results comparable.

A comparison of a portable blood lactate analyser and laboratory plasma analysis of blood samples from exercised horses

Quick, simple methods for blood lactate analysis could be helpful in evaluating xercise response in the field, but methods validated for analysis of blood collected after high intensity exercise in horses are scarce. The aim of the present study was to compare the results obtained using a commercial, portable blood lactate analyser with those from laboratory plasma analysis of blood samples from horses performing intensive exercise. Venous blood samples were collected from 220 horses within 5 min of performing exercise at a mean peak heart rate of 222 ±9 beats/min. The samples were kept chilled and analysed using portable analyser within 10 min of collection. Samples were also centrifuged and the plasma frozen (-20 °C) until analysed using an enzymatic and spectrophotometric laboratory lactate analysis. There was a significant (P<0.05) correlation (R=0.94) between the methods at portable analyser values <12.0 mmol/l, but at higher values there was no correlation. There was a significant effect of method (P<0.0001) and portable analyser values were 21% lower than plasma lactate concentrations in the range 2.0-12.0 mmol/l. It is concluded that the portable analysis correlated well to a laboratory plasma analysis at portable analyser values <12.0 mmol/l and that the portable analyser appears to be a safe method for lactate analysis during training conditions, when very high lactate concentrations are not expected. However, users should be aware that the results underestimate the corresponding plasma values by approximately 20%.