Field exercise testing for assessing fitness in French standardbred trotters.

This review considers standardized exercise testing which is, routinely used for French Trotters in the field. Track testing provides a more limited range of measurements than treadmill testing, but has the advantage of being performed in the horse's natural environment. Various measurements such as heart rate during exercise and blood lactate concentration after exercise may be measured on the track and lead to the calculation of physiological variables such as V200 (velocity corresponding to a 200 bpm heart rate) and V4 (velocity corresponding to a 4 mmol/L blood lactate concentration). V4 is related to the onset of blood lactate accumulation and relates to the aerobic capacity of the horse, as horses with high values for V4 have higher aerobic capacities. Although V4 is calculated during submaximal intensity exercise, it is related to racing performance and seems to be the most important measurement to assess changes in fitness. V200 represents the cardiac capacity of the horse during exercise and is close to V4 in mature horses. To explain further the clinical usefulness of track testing, and to help interpret both V4 and V200 variables, examples of exercise tests in 3-year-old French Trotters are presented here. These results show that changes may occur in V4 and V200 according to different factors such as the horse's physical ability and either training or disease states. It underlines the importance of exercise tests for both trainers and veterinarians and how they may help in the evaluation of a horse's performance ability; in defining the intensity of a training program, and also in the early detection of underlying diseases.