Reproducibility of endurance capacity and VO2peak in male Sprague-Dawley rats

Departments of Kinesiology, Anatomy, and Physiology, Kansas State University, Manhattan, Kansas Submitted 4 December 2008 ; accepted in final form 6 February 2009 The rat model of treadmill running is an invaluable tool for the investigation of experimentally and pathologically induced alterations in exercise performance. Interpretation of such data often presumes knowledge of the within-rat reproducibility of performance measures; however, the literature is bereft of this information. We tested the hypothesis that within-rat exercise endurance capacity and peak O 2 uptake ( O 2peak ) are highly reproducible across five measurements spanning 5 wk when assessed with treadmill performance protocols. Male Sprague-Dawley rats ( n = 13) performed five graded exercise tolerance tests to fatigue and five maximal exercise tests on a motor-driven treadmill for determination of endurance capacity and O 2peak , respectively. There were no differences ( P = 0.47) in average time to fatigue among any of the five exercise tolerance tests (average range 45.9–52.1 min), and the average within-rat coefficient of variation (CV) over the five runs was 0.13. There were no differences ( P > 0.05) among the average CVs from any consecutive weekly exercise tolerance tests (range of 4 CVs 0.06–0.10). As expected with the increase in body mass, relative O 2peak decreased (average range from 80.1 to 75.7 ml·min –1 ·kg –1 , P < 0.05) throughout the five maximal exercise tests. However, there were no differences ( P = 0.63) in the average within-rat CVs among any consecutive O 2peak tests (range of 4 CVs 0.03–0.04), and the average within-rat CV for all five tests was 0.06. The present data obtained from the protocols described herein demonstrate that within-rat measurements of endurance capacity and O 2peak are highly reproducible. These results have significant implications for improving and refining exercise testing and experimental designs. exercise performance; reproducibility; maximal oxygen uptake; treadmill running Address for reprint requests and other correspondence: T. I. Musch, Dept. of Anatomy and Physiology, College of Veterinary Medicine, Kansas State Univ., Manhattan, KS 66506-5802 (e-mail: musch{at}vet.ksu.edu )