A field study of oxygen consumption and estimated energy expenditure in the exercising horse

The major goal of this study was to estimate the aerobic and anaerobic cont ribution to energy expenditure in the running warmblood horse under field c onditions. 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 im mediately following exercise the relative oxygen debt (RD-VO2) was measured . The horses were exercised by riders in the various gaits at speeds repres enting 15, 30, 50 and 70% of the their individual maximum speed (V-max). Th e distances covered were 3000 in in each walk, trot and canter and 1500 m i n 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 st udied for possible relations to the speed. The proportion of anaerobic ener gy expenditure (%E anaer.) to the total energy production was also investig ated. A linear relation between speed and aerobic energy expenditure (E) an d a quadratic relation between speed and anaerobic energy expenditure (RD-E ) and total energy expenditure (TF) was found. The %E anaer. was 1.21 +/- 0 .40 at a speed of 15% V-max,3.40 +/- 0.38 at 30% V-max, 18.58 +/- 2.05 at 5 0% V-max, and 29.47 +/- 1.17 at 70% V-max. Post-exercise oxygen uptake appears a suitable measure for the major part o f the oxygen debt (relative oxygen debt) and could be considered as an indi cator of anaerobically released energy. For this reason it may also be an i ndicator of the anaerobic capacity of the horse at a standard or maximal ex ercise.