A valid and reproducible protocol for testing maximal oxygen uptake in rabbits

Physiological studies of long-term cardiovascular adaptation to exercise require adequate testing procedures to quantify the outcome. Such test procedures are well established in rats and mice. However, the use of these species may have limitations, and to study several physiological parameters mimicking ‘the human adaptation’ larger animal models may be preferable. Here, we established a valid and reproducible exercise test protocol for measuring maximal oxygen uptake (VO_2max) in rabbits.

The VO_2max protocol was studied in six adult female New Zealand White rabbits running on a treadmill at inclinations ranging from 0 to 20°.VO_2max was reached at all inclinations indicating that the rabbits reach exhaustion independent of inclination. Average VO_2max for test and retest were 35.1 ± 4.2 and 35.8 ± 4.0 ml/kg per min, respectively. Oxygen uptake and heart rate increased linearly with increased running speed. Average running speed at VO_2max was 0.51 ± 0.09 m/s, and there was an increase oxygen pulse up to the intensity corresponding to VO_2max, where it leveled off and declined.

This study shows that rabbit is a suitable species for studying responses to training and could be of great importance for showing novel cellular cardiac adaptations to training.