Maximum oxygen consumption and quantification of exercise intensity in untrained male Wistar rats

This study aimed to explore a valid test protocol for measuring VO2max in healthy untrained male Wistar rats of different ages and quantifying the exercise intensity (%VO2max) of running under different treadmill grades and speeds. The test protocols and %VO2max will provide a reference for the design of exercise intensity. We tested male Wistar rats aged 4 weeks, 10 weeks, 10 months and 16 months old with three test protocols (Procedure 1 [P1], 2 [P2] and 3 [P3]) for each age group to quantify VO2max. We analysed VO2max, respiratory exchange ratio and test duration to determine an optimal test protocol of VO2max for different age groups. We used the optimal test protocol to explore the changes in age-related VO2max. Finally, %VO2max of running under different treadmill speeds and grades was quantified. VO2max of Wistar rats decreased significantly after the age of 4 weeks (p<0.05). The optimum VO2max can be induced by personalised protocols for different ages. In 4-week-old Wistar rats, the highest VO2max values were attained by P1 (104.4 +/- 6.9 mL.kg(-1).min(-1), p=0.032). The highest VO2max value (84.7 +/- 3.7 mL.kg(-1).min(-1), p=0.037) of 8-week-old Wistar rats was attained in P2. In 10-month-old Wistar rats, the highest VO2max value was obtained in P3 (63.3 +/- 1.7 mL.kg(-1).min(-1)). This work could be used as a reference for assessing aerobic capacity in studies on exercise intervention with untrained male Wistar rats. However, the %VO2max measurements at various treadmill speeds and grades only apply to untrained male Wistar rats.