Application of spirometry during standard incremental exercise test on treadmill for respiratory gas exchange evaluation of Arabian horses

Abstract

The current study evaluated equine gas exchange responses through spirometry, by measuring oxygenuptake (VO2), carbon dioxide production (VCO2), respiratory exchange ratio (R) and maximum oxygenuptake (VO2max) of Arabian horses during a standard incremental exercise test performed on a high-speedtreadmill. Six clinically healthy Arabian horses were submitted to a standard incremental exercise test,performed on a high-speed treadmill at a 6% slope, and initial speed of 1,8 m.s-1 for 5 minutes, then 4,0m.s-1 for 3 minutes, 6,0 m.s-1 for 2 minutes and 8,0 m.s-1, 9,0 m.s-1, 10,0 m.s-1 and 11,0 m.s-1 for oneminute for each of these speed. The end of the exercise test was defined as the point in which the horse wasno longer able to keep pace with the treadmill. Gas exchange was measured through respiratory analyseshorse mask on the last 10 seconds at the end of each speed transition and at 1, 2 and 3 minutes after theend of the exercise, defined as experiment moments. During exercise, it was noticed an increase on bothVO2 and VCO2 with linear relationship between exercise and speed. Arabian horses VO2max was 114,9mL.kg-1.min-1. The respiratory exchange ratio increased over 1,0 by the speed of 9,0 m.s-1, indicating thepreponderance of the anaerobic metabolism, and remains at a high level on the post-exercise period.