67
from ischemic mitral regurgitation during an extended follow-up period but does
not significantly influence left ventricular remodeling in a clinically relevant ovine
model of ischemic mitral regurgitation [ 35 ]. Overall, sheep can be a good pre-
clinical animal model for cardiovascular research [ 7 ].
3.3.6 Other Animal Exercise Models (Horses, Goats)
As the quality of the overall response to exercise in the horse is very similar to that
seen in human and laboratory animals, exercise studies on horses have dramatically
increased knowledge of horse physiology and pathophysiology [ 46 , 71 , 84 ]. The
responses of heart rate, blood lactate concentration, packed cell volume, and hemo-
globin after endurance exercise were evaluated in crossbreed horses [ 85 ].
Cardiorespiratory responses to submaximal treadmill exercise were investigated in
thoroughbred racehorses [ 86 ]. After submaximal training, an increased aerobic
power was associated with an increase in maximal cardiac output and stroke vol-
ume, a decrease in arteriovenous oxygen difference, and no change in heart rate
[ 86 ]. In order to better understand the relationship between cardiac structure,
mechanics, and overall function adaptation during athletic training, exercise-
induced cardiac remodeling in racehorses was designed to study cardiac remodeling
in aerobic exercise [ 36 , 87 ]. A recent review has proposed that cardiac remodeling
in response to athletic training in racehorses may provide greater insight into the
potential for athletic activity to remodel the heart [ 36 ].
Goats, an alternate animal species, performed volitional aerobic exercise forfood rewards [ 3 ] and was used to study the effects of diet and exercise on fatty
lesion of the aorta in a model of high-fat diets [ 88 ]. Previous research using pygmy
goat suggested that maternal cardiac output response to exercise appears normal,
the post-exercise fall in stroke volume, presumed secondary to a reduction in pre-
load, could potentially be harmful to both mother and fetus [ 89 ]. Additionally, the
elevations in heart rate and stroke volume in pregnancy are not primarily mediated
via the autonomic nervous system.
4 Conclusion
Taken together, the positive influence of exercise on cardiovascular health to lifes-
pan has become a topic, and the choice of the animal models is an important deter-
minant of the relative disease model to the human situation [ 3 ]. Thus, studies in
cardiovascular system should use varied animal models to achieve the scientific
goals [ 6 ]. The research outcomes should answer whether a certain exercise protocol
has produced expected adaptive responses, including detailed concerns related to it.
4 Acute and Chronic Exercise in Animal Models