Journal of Applied Physiology, Vol 57, Issue 2 601-607, Copyright © 1984 by American Physiological Society
Oxygen consumption and hemodynamic responses during graded treadmill exercise in the dog
G. A. Ordway, D. L. Floyd, J. C. Longhurst and J. H. Mitchell
A description is given of a technique that provides a relatively simple
means by which O2 consumption and hemodynamic variables can be measured in
exercising dogs. We used a multistage submaximal treadmill test to study
the responses of 10 foxhounds to dynamic exercise. They were also studied
during maximal treadmill exercise. O2 consumption increased from 16.3 +/-
1.7 ml O2 X min-1 X kg-1 at rest to 92.9 +/- 9.7 ml O2 X min-1 X kg-1 at a
work load of 6.4 km/h, 20% grade and to 111.9 +/- 9.6 ml O2 X min-1 X kg-1
during maximal exercise. Cardiac output (CO) increased from 6.11 +/- 0.45
l/min at rest to 16.91 +/- 1.46 and 17.66 +/- 0.60 l/min at 6.4 km/h, 20%
grade and maximal exercise, respectively. Arteriovenous O2 difference
increased from 5.8 +/- 0.3 vol% at rest to 12.0 +/- 0.4 and 13.2 +/- 0.7
vol% at 6.4 km/h, 20% grade and maximal exercise, respectively. Heart rate
(HR) increased from 116 +/- 7 beats/min at rest to 250 +/- 8 beats/min at
6.4 km/h, 20% grade and to 278 +/- 6 beats/min during maximal exercise. O2
uptake, CO, and arteriovenous O2 difference increased with the onset of
exercise, appeared to level at lower work intensities (6.4 km/h, 4 and 8%
grade), and increased significantly at each of the higher work intensities
(6.4 km/h, 12, 16, and 20% grade). Additionally, we observed linear
relationships between O2 consumption and HR (HR = 1.35 X VO2 + 120.5; r =
0.87; P less than 0.001) and between O2 consumption and CO (CO = 5.91 X VO2
+ 216.6; r = 0.96; P less than 0.001). Further, the linear relationship
between O2 consumption and CO demonstrated in the present study is similar
to that observed in humans.
