[Various aspects of lactate production and disappearance in trotters during exertion]

Venous lactate concentrations were determined in standard-bred trotters following exercise of varying intensity to obtain a useful parameter in determining the working capacity of horses. After standard exercise, well-trained horses produced less lactate than did inadequately trained horses. During the post-exercise resting period, lactate disappeared faster from the blood in well-trained horses and young lightly trained horses than it did in poorly trained horses. Steady-state training resulted in lower lactate levels than those recorded after racing, whereas interval training resulted in the highest lactate levels. Measuring post-exercise venous lactate concentrations was useful in determining the state of training and in assessing the work-load of a horse. It was not possible to predict the racing potential of a horse on the basis of a post-exercise lactate level after standardized exercise in the present study.