If I remember my biochemistry from 1963 correctly,
the metabolic pathway that changes sugar into energy and water and carbondioxide
produces lactic acid partway through the pathway.
This part of the path, produces energy without
requiring oxygen. It is extremely useful because it enables energy to be
produced faster that oxygen can be obtained from the air through the
lungs. Thus, the horse can sprint very fast to outrun the Lion. Of
course, the Lion's body is doing the same thing.
Now relatively quickly (a time frame of minutes)
enough lactic acid builds up and the animal starts to feel fatigued. If it
is a person and they are playing for the Edmonton Oilers, they go to the bench
and recover. If they are a horse running in the Kentucky Derby, the race
is over by that time.
If they are a horse in an Endurance Ride, or a
human Marathoner who is exercising at a rate greater than their lungs can
supply oxygen for a long time (hours) they will start to get muscle cramps
etc. If you then add to this some genetic defects in the sugar
storage/usage system you get a badly tied up horse.
The moral, is that if you expect an animal to
exercise for many hours, they must exercise at an average rate equal or below
that which can be sustained by the oxygen delivered by their lungs. Note I
said average. A horse, or person, can "go anaerobic" for a short time
going up a hill, and catch up later on the down hill. During the catch up
phase the lactic acid is utilized to produce energy and the final waste products
water and carbon dioxide.
Ed
Ed & Wendy Hauser 2994 Mittower
Road Victor, MT 59875
