Effect of three different warm-up regimens on heat balance and oxygen consumption of Thoroughbred horses

Horses were exercised at 105% of their maximal O-2 uptake until fatigued after three different warm-up regimens (no warm-up, a light warm-up, and a warm-up until the central venous temperature was >39.5 degrees C) to assess the effect of the warm-up on the various avenues of heat loss. Approximately 12.79, 15.10, and 18.40 MJ of heat were generated in response to the warm-up and exercise after the three different warm-up regimens, respectively. Of the heat generated, 17.5, 17.2, and 17.4% remained as stored heat after 20 min of active recovery. Heat loss from the respiratory system was 63.6, 33.7, and 40.3% of the heat produced during and after the three warm-up intensities, respectively. The balance of the heat loss was assumed to be via the evaporation of sweat. On this basis, the heat loss by sweating was 14.9, 49.1, and 42.3% of the heat produced during and after the three warm-up intensities, which represented evaporation of 0.8, 3.1, and 3.0 liters of sweat, respectively. O-2 consumption during exercise and heart rates 20 min postexercise, after two of the warm-up regimens, was significantly lower than that after no prior warm-up.