A Field Study of Oxygen Consumption and Estimated Energy Expenditure in the Exercising Horse

Hanák J . , P . Jahn, R. Kabe‰, M. Sedl inská, Z. Îert , J . Mezerová, O. Chvátal : A Field Study of Oxygen Consumption and Estimated Energy Expenditure in the Exercising Horse. Acta Vet. Brno 2001, 70: 133-139. The major goal of this study was to estimate the aerobic and anaerobic contribution to energy expenditure in the running warmblood horse under field conditions. The oxygen consumption (VO2) in 12 saddle horses was determined at rest, walk, trot, and canter and in 6 horses at gallop. In the 10 min immediately following exercise the relative oxygen debt (RD-VO2) was measured. The horses were exercised by riders in the various gaits at speeds representing 15, 30, 50 and 70% of the their individual maximum speed (Vmax). The distances covered were 3000 m in each walk, trot and canter and 1500 m in gallop. VO2 and RD-VO2 m and energy expenditure (J.kg.min -1) using the oxygen caloric equivalent of the measured respiratory quotient (RQ) were studied for possible relations to the speed. The proportion of anaerobic energy expenditure (%E anaer.) to the total energy production was also investigated. A linear relation between speed and aerobic energy expenditure (E) and a quadratic relation between speed and anaerobic energy expenditure (RD-E) and total energy expenditure (TE) was found. The %E anaer. was 1.21 ± 0.40 at a speed of 15% Vmax, 3.40 ± 0.38 at 30% Vmax, 18.58 ± 2.05 at 50% Vmax, and 29.47 ± 1.17 at 70% Vmax. Post-exercise oxygen uptake appears a suitable measure for the major part of the oxygen debt (relative oxygen debt) and could be considered as an indicator of anaerobically released energy. For this reason it may also be an indicator of the anaerobic capacity of the horse at a standard or maximal exercise. Horse, exercise, oxygen uptake, oxygen debt, energy consumption, anaerobic energy In recent years, a considerable amount of research has been performed in an attempt to describe the physiological response of the horse to exercise and training. Mostly the changes in cardiorespiratory functions during different intensities of exercise have been studied extensively and reported for various breeds of horses. It has been suggested that heart rate and oxygen consumption (VO2), measured at sub-maximal exercise, are useful in assessing cardiovascular fitness in the horse. Calculated parameters such as the speed at a heart rate of 200 beats.min-1 (V-200) and oxygen consumption at a heart rate of 200 beats.min-1 (VO2-200) are considered as highly useful (Persson 1983; Persson et al. 1983; Rose et al. 1990). Other suitable indices of fitness have included the velocity (V) and heart rate (HR) at a blood lactate concentration of 4 mmol.l-1 i.e. VLa4 and HR4, respectively (Rose et al. 1990; Harkins et al. 1993; Poso et al. 1993; Castejon et al. 1994; Misumi et al. 1994; Gotlieb-Vedi et al. 1995; Persson 1997; Munoz et al. 1997; Eaton et al. 1999 and others). While sub-maximal indices have been commonly used to predict the maximum working capacity, there are relatively few studies in which the cardiorespiratory measurements have been performed during maximal exercise or in which energy expenditure and heat production have been calculated from oxygen uptake and post exercise oxygen debt (Karlsen and Nadal jak 1972; Rose et al. 1988; Eaton et al. 1995). ACTA VET. BRNO 2001, 70: 133–139 Address for correspondence: Prof. MVDr. Jaroslav Hanák, DrSc. Equine Clinic University of Veterinary and Pharmaceutical Sciences Palackého 1-3, 612 42 Brno, Czech Republic Phone: x 420-5-4156 2373 Fax: x 420-5-4156 2395 E-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm