ABSTRACT
The VO 2max value was established from twelve pigs, followed by checks of their responses to endurance stress (walk 0.7 m/sec, ambient temperatures between 22 degress C and 24 degrees C, relative humidities between 67 and 78 per cent). Also measured were the rectal temperature, heart rate, respiratory rate, haemoglobin level of the blood, haematocrit, mean corpuscular haemoglobin concentration, plasma volume, blood volume, total haemoglobin, plasma glucose concentration and plasma lactid acid concentration. A differentiation could be made between one group weighing between 53.3 +/- 2.47 kg and enduring 97 +/- 9 minutes and another weighing 60.0 +/- 1.38 kg and enduring 36 +/- 6 minutes. The two groups differed from one another for their plasma and blood volumes, their values being 42.6 +/- 3.8 ml/kg and 67.5 +/- 7.5 ml/kg or 33.5 +/- 3.4 ml/kg and 52.2 +/- 5.9 ml/kg. The groups produced quantitatively different responses to endurance stress. The demands implied in endurance were widely met by the circulatory system, while the energy transfer was characterised primarily by aerobic energy collection.
