Exercise Physiology

Question 1

What is the athletic ability of a horse best measured by?

Answer 1

VO2max= HR X SV X (a-v)O2

Question 2

What is the VO2max comparison of a horse to a cow?

Answer 2

2.5 times that of a cow

Question 3

T/F: The HR, SV, and CO are all similar in equine and bovine?

Answer 3

FALSE- HR similar but SV and CO greater in equine

Question 4

What is the at rest vs. end of race HR of a horse?

Answer 4

At rest: 26-44

End of race: 180-250

Question 5

What % of body weight is contributed to muscle in equine?

Answer 5

50%

Question 6

What two components of muscle are higher in the horse?

Answer 6

Higher concentration of glycogen and increased number of mitochondria- more aerobic work

Question 7

What three factors allow for high aerobic exercise capacity?

Answer 7

1. capacity for huge increase in O2 delivery to muscles
2. increase RBC numbers
3. reach greater O2 extraction than other species

Question 8

How is energy supplied in initial exercise?

Answer 8

use of stored energy- ATP, PCr, and ADP-myokinase

Question 9

What pathway generates a tremendous amount of ATP but is only sustained for a few seconds?

Answer 9

Phosphocreatine Pathway- used in initial seconds allowing anaerobic pathway to come up to speed

Question 10

Where does anaerobic glycolysis occur in respect to the mitochondria?

Answer 10

External to the mitochondria-cytoplasm

Question 11

When is anaerobic glycolysis used?

Answer 11

Submaximal activity producing lactate and ATP

Question 12

What is the best use of the anaerobic glycolysis pathway?

Answer 12

supplement to aerobic pathway during specific segments of exercise bouts

Question 13

Where do aerobic pathways occur?

Answer 13

Mitochondria

Question 14

How much more ATP does FFA create?

Answer 14

3X more amount of ATP

Question 15

What percentage of energy comes from aerobic metabolism in sprinting horses?

Answer 15

70-80%

Question 16

Low intensity exercise is mostly what type of energy pathway?

Answer 16

mostly aerobic

Question 17

At 20-30% glycogen use, the body switches to what for energy sources?

Answer 17

fat as substrate

Question 18

What are the three forms of muscle fibers?

Answer 18

Type I, Type IIA, Type IIX

Question 19

Which fiber has slow hydrolysis of ATP, low glycogen content, high capillary number, high oxidative capacity, seen in forelimbs and fatigue slowly?

Answer 19

Type I

Question 20

Which fiber generates force rapidly, has large number of capillaries/mitochondria and sustain high power for prolonged periods and is seen in the hindlimb muscles?

Answer 20

Type IIA

Question 21

Which fiber generates force rapidly, high power/limited duration and 3X faster than IIA and is seen in the hindlimb muscles?

Answer 21

Type IIX

Question 22

What is the predictable pattern of muscle fiber usage?

Answer 22

Type I –> IIA –> IIAX –>IIX

Question 23

What muscle fiber is only recruited near maximal intensity?

Answer 23

Type IIX

Question 24

Fatigue in aerobic metabolism is associated with what?

Answer 24

Glycogen depletion-occurs first in type I fibers

Question 25

Fatigue in anaerobic metabolism is correlated to what fiber type?

Answer 25

Type II

Question 26

How is the circulating red cell volume increased in turn increasing oxygen carrying capacity?

Answer 26

Splenocontraction

Question 27

Splenocontraction not only increases oxygen carrying capacity and RBC but also increases what else?

Answer 27

SV and MAP

Question 28

What can occur in the vessels of a horse that is performing in 60-70% PCV range?

Answer 28

Sludging(increased viscosity) causing detrimental effects to the flow

Question 29

What is the HR of an exercising horse?

Answer 29

220-240 bpm

Question 30

Venous return is enhanced by what three factors?

Answer 30

vasoconstriction muscle contraction intrathoracic pressure changes

Question 31

How does intrathoracic pressure change influence the flow of blood?

Answer 31

Thorax pressure is more negative increasing the flow from where it is coming from and traveling back to the thorax

Question 32

What is the relationship between minute ventilation and speed?

Answer 32

Linear increase

Question 33

Minute ventilation increase results from an increase in what?

Answer 33

RR and Tidal volume

Question 34

Low tissue O2 concentration set up hgh a-v O2 gradient favoring what?

Answer 34

O2 off loading to tissues

Question 35

Improved O2 extraction has what kind of dissociation curve?

Answer 35

Right shift- hypercarbia and hyperthermia and tissue acidosis

Question 36

Why at intense exercise is there a limitation of oxygen uptake?

Answer 36

Exercise exceeding 65% VO2max will be associated with hypoxemia because the blood is traveling so fast that there is not enough time for full saturation of O2

Question 37

What is the normal PaO2 in equine?

Answer 37

80-110 mmHg

Question 38

What is the relationship between footfall and RR when a horse is at canter and gallop?

Answer 38

coupled in a 1:1 ratio- limiting RR to maximum of 130/min

Question 39

What is the resistance to flow in the respiratory system?

Answer 39

Upper airway

Question 40

If there is shortened diastole-how does that affect the heart?

Answer 40

Majority of perfusion to coronary vessels occurs during diastole. So if you shorten diastole-then you will decrease cardiac perfusion leading to arrhythmias

Question 41

What is a major CVS adaptation to increased athletic performance?

Answer 41

heart mass increased

Question 42

What is the likely muscle fiber conversion?

Answer 42

IIX --> IIAX --> IIA --> I&IIA --> I

Question 43

The exercise capacity of a horse is limited by what?

Answer 43

O2 delivery and diffusion of O2 to the muscles