key: cord-0008475-9d22qwti
authors: Rose, R.J.
title: Equine exercise physiology—New horizons
date: 2007-11-19
journal: Br Vet J
DOI: 10.1016/0007-1935(88)90042-5
sha: 5894b74f59031a5d2da9ee87c918c322b47d45ff
doc_id: 8475
cord_uid: 9d22qwti

nan

infectious diseases regularly cross national frontiers or move from one continent to another and the susceptibility of livestock to disease is influenced by changes in management practices, husbandry systems and nutrition .

One has only to consider events over the last few years to appreciate the significance of these observations with the recognition of paramyxovirus in pigeons and transmission to poultry ; the mutation of avian influenza in poultry flocks in the US ; the emergence of turkey rhinotracheitis as a serious threat to the turkey industry ; the recognition of respiratory corona virus in pigs ; the occurrence of classical swine fever in Great Britain and African swine fever in Belgium and Holland ; the increasing prevalence of H3 N2 influenza virus in pigs and most recently the discovery of an encephalopathy of unknown cause in cattle with similarities to the known transmissible spongiform encephalopathies in animals and man .

Disease monitoring and surveillance programmes for the early recognition of new problems are essential if the industry's needs are to be met and the national investment in livestock and export markets protected . The Chernobyl accident, the subject of a paper in this journal, focused attention on an unexpected health hazard justifying overnight the investment in the terrestrial radioactive monitoring programme capable of rapid expansion in such an emergency .

If a veterinary service is to operate effective surveillance programmes, it must maintain regular contact with livestock units and have the resources with the flexibility to undertake comprehensive research programmes when the need arises . Present perceived needs to increase the revenue from advisory work and contract R & D must therefore be carefully balanced against other considerations of equal or greater long-term importance to the national economy . W . A . WATSON, Central Veterinary Laboratory

Scientific studies of the physiology of exercise have their origin in Sweden in the 1960s . Professor Sune Persson was the first to investigate work capacity using a treadmill especially designed for exercising horses . His 1967 monograph examined the role of the circulating red cell mass in determining performance in Standardbred trotters . Not only did Persson show a good relationship between time per km and total haemoglobin, but he also reported a decrease in performance in overtrained horses that had Oolycythaemia . In the 20 years since this work was published, a variety of different areas have been investigated in the broad area of exercise physiology . Much work has been undertaken ,on the endurance horse (Rose, 1986) and Standardbred trotters, but there is less information on horses involved in flat or steeplechase racing or eventing . However, there has been a great increase in the amount of interest and research in the area of equine exercise physiology during the past 5 years . At the Second International Symposium on Equine Exercise Physiology, held in San Diego in August 1986, approximately 60 papers and posters were presented . At this conference it was clear that one of the major technological advances was the availability of high speed treadmills, especially designed for horses . Treadmills capable of speeds up to 14 m/s, allow both submaximal and maximal exercise to be studied, with measurements performed during exercise . Prior to treadmills being used, most measurements could only be obtained before and after exercise, so that limited information was procured . Treadmills are now in use in Scandinavia, Europe, UK, Australia and USA, where research groups are active in various areas of equine exercise physiology .

Our interest at the University of Sydney has been in defining exercise capacity and performance limitations in horses . As part of this research, we developed a suitable exercise protocol for the measurement of maximum oxygen uptake ( V O2max), a measurement that has long been used in human exercise physiology to define aerobic capacity . Using a high speed treadmill and a respiratory gas collection mask for measuring the composition and volume of expired gas, Vo2max was reliably measured (Evans & Rose, 1987a) . We found that horses have VO2max values up to double those of highly trained human endurance athletes (Evans & Rose, 1987b) . Furthermore, VO2max can be increased significantly in response to training (Evans & Rose, 1987c) . Although VO 2m~is the single best index of aerobic capacity, the question to be answered is whether horses with high VO2max values are superior performers to those with lower values . The answer to the question will of course depend on the type of competitive activity being undertaken . Horses racing Over distances of 400-1000 m are probably more dependent on their anaerobic capacity and neuromuscular coordination .

Although a mask is necessary for VO2max measurement, masks with valves may cause hypoxaemia and hypercapnia (Evans & Rose, 1987d) . For future studies where measurements of gas exchange are required, a `flow-through' mask system without valves is likely to be the most appropriate design (Bayly et al., 1987) . In this system, vacuum motors are used to suck air around and through the mask at a rate of approximately 70001/min . At these high flow rates the mask does not cause alterations in arterial blood gas values, when compared with those in horses during exercise without a mask (Bayly et al., 1987) . Because hypoxaemia is found in horses during high intensity exercise, future studies of gas exchange and ventilation are important in defining limiting factors to maximal exercise . Research areas such as muscle metabolite changes and oxygen debt and deficit with supramaximal exercise can be studied (Rose et al., 1987) . High speed treadmills will continue to be of great use in equine exercise physiology research . Studies relating to performance limitations as well as investigation of different training programmes will not only be of benefit to the horse industry, but are also of comparative physiological interest .

Research in Veterinary Science in press