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LAM 1 > Exercise Physiology > Flashcards

Exercise Physiology Flashcards

1
Q

Exercise requires what 2 things?

A
  • Energy supply for the muscles

- Oxygen delivery to this tissues

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2
Q

Thoroughbreds typically race what distance range?

At what speed?

A
  • Distance: 800-5000 meters

- 64 km/hr, 40 mph

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3
Q

Quarter horses typically race at what distance?

At what speed?

A
  • Distance:
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4
Q

What is the maximum oxygen consumption level seen with fit racehorses?
How much greater is this compared to cattle?

A
  • 160 ml/kg/min

- 2.6 times that of cattle

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5
Q

How does HR, CO and SV compare between a fit racehorse and cattle?

A
  • HR similar to cattle

- CO and SV greater in horses

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6
Q

Are muscle mass and lung field generally larger in a horse or cattle?

A

Horse

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7
Q

How much larger are the lungs of a horse compared to cattle?

Surface area?

A
  • Lungs 2X size of cattle

- 1.6 times greater surface area

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8
Q

The heart mass of a horse is typically what percentage of their body weight?

A

0.9-1% of body weight

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9
Q

Muscle mass in horses is what percentage of body weight?

A

50% of body weight

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10
Q

Do horses have a higher or lower concentration of intramuscular glycogen compared to other species?
What is the amount?

A
  • Higher concentration

- 140 mmol/kg of muscle

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11
Q

How much greater is the ratio of mitochondria per unit of muscle weight in horses compared to cattle?

A

2 times greater in horses

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12
Q

The combination of what 2 factors make horses good at aerobic exercise?

A
  • Higher concentration of intramuscular glycogen

- Larger number of mitochondria per unit of muscle weight

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13
Q

What are 2 different storage forms from which energy can be utilized?

A
  • Intramuscular glycogen and triglycerides

- Extra-muscular stores such as adipose tissue and liver glycogen

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14
Q

What are 3 forms of readily usable energy?

A
  • ATP
  • Phosphocreatine Pathway
  • ADP-myokinase
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15
Q

Which energy pathway can create a tremendous amount of ATP in a fraction of a second?

A

Phosphocreatine pathway

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16
Q

Which energy pathway is only utilized during the initial seconds of exercise?

A

Phosphocreatine pathway

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17
Q

Which energy pathway allows other pathways to come up to speed?

A

Phosphocreatine pathway

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18
Q

With the anaerobic pathway, how much ATP is produced?

How quickly?

A
  • Small amount of ATP

- Very rapid production of energy

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19
Q

With the anaerobic pathway, what is produced from pyruvate?

Where does this take place?

A
  • Lactic acid

- In cytoplasm

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20
Q

With the aerobic pathway, what is produced from pyruvate?

Where does this take place?

A
  • Acetyl CoA

- In mitochondria

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21
Q

What does the aerobic pathway depend on?

A

Depends on continuous O2 supply.

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22
Q

Which pathway generates more ATP, aerobic or anaerobic?

A

Aerobic

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23
Q

What is an example of an aerobic pathway?

A

Beta oxidation of free fatty acids

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24
Q

Beta oxidation of free fatty acids produces how much more ATP?

A

3x more

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25
Q

Which aerobic pathway requires more oxygen?

Is the rate of energy production with this pathway fast or slow?

A
  • Beta oxidation of free fatty acids

- Rate of energy production slow

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26
Q

Is low intensity exercise largely aerobic or anaerobic?

A

Largely aerobic

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27
Q

At what point with low intensity exercise will the energy source move to fat as a substrate?

A

At 20-30% glycogen depletion

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28
Q

Free fatty acid oxidation is highest at what percentage VO2 max?

A

40-60%

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29
Q

What happens as intensity of exercise increases?

A

Additional work above this engenders oxidation of carbohydrates.

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30
Q

If intensity is increased but still within limits of the aerobic pathway, what happens?

A

Glucose from circulation is used and glycogen from intramuscular stores are mobilized.

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31
Q

With an increase in intensity come an increase in what?

A

Increase in oxygen demand and delivery.

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32
Q

What happens with a further increase in intensity?

What does this lead to?

A
  • ATP needs are not met by oxygen delivery

- Anaerobic pathway

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33
Q

What are 5 factors that the proportion of energy derived from each storage form are dependent on?

A
  • Speed
  • Feed
  • fitness
  • Muscle fiber composition
  • Age of the horse
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34
Q

At 30% exercise intensity (VO2 max), what percentage of energy expenditure comes from glucose?
Fat?
Glycogen?

A
  • 10%
  • 60%
  • 30%
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35
Q

At 60% intensity (VO2 max), what percentage of energy expenditure comes from glucose?
Fat?
Glycogen?

A
  • 10%
  • 35%
  • 55%
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36
Q

How are muscle fiber types differentiated?

A

Differentiated by myosin heavy chain isoforms.

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37
Q

What are the 3 pure forms (contain a single isoform) of muscle fibers seen in horses?

A
  • Type I
  • Type IIA
  • Type IIX
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38
Q

What are the 2 hybrid forms of muscle fibers seen in horses?

A
  • Type I and IIA

- Type IIAX

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39
Q

What type of fibers are slow twitch oxidative fibers?

A

Type I fibers

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40
Q

How quickly do Type I fibers hydrolyze ATP?

A

Hydrolyze ATP slowly

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41
Q

Which type of fibers have a high number of capillaries and a high oxidative capacity?

A

Type I fibers

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42
Q

Do Type 1 fibers fatigue quickly or slowly?

A

Fatigue slowly

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43
Q

What type of movement are Type I fibers responsible for?

A

Slow repetitive movement

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44
Q

What do Type I fibers sustain?

What are they poor at?

A
  • Sustain isometric force

- Poor at power generation

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45
Q

Do Type I fibers form small or large bundles?

A

Small bundles

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46
Q

What type of fibers are fast twitch?

A

Type II fibers

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47
Q

What type of fibers show fast cross-bridging cycles?

A

Type II fibers

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48
Q

Do Type II fibers generate force slowly or rapidly?

A

Generate force rapidly

49
Q

What type of fibers are fast oxidative glycolytic (FOG) fibers?

A

Type IIA fibers

50
Q

What type of fibers have large numbers of capillaries and mitochondria?

A

Type IIA fibers

51
Q

Which type of fibers utilize glycolytic and oxidative mechanisms?

A

Type IIA fibers

52
Q

How long can Type IIA fibers sustain high power?

A

For prolonged periods

53
Q

What type of fibers are fast glycolytic fibers (FG)?

A

Type IIX fibers

54
Q

How much faster are Type IIX fibers compared to Type IIA fibers?

A

3x faster than Type IIA fibers

55
Q

Do Type IIX fibers form small or large bundles?

A

Large bundles

56
Q

What are Type IIX fibers adapted for?

A

Adapted for high power output with limited duration.

57
Q

Do Type IIX fibers have a high or low number of capillaries?

A

Low number of capillaries

58
Q

Type IIAX fibers are intermediate between what other 2 fiber types?

A
  • Type IIA fibers

- Type IIX fibers

59
Q

The forelimb is mainly composed of what type of muscle fibers?

A

Type I fibers

60
Q

Since the hindlimbs are the main source of propulsion, they have a high proportion of what muscle type?

A

Type II fibers

61
Q

Posture maintenance is controlled by what type of fibers?

A

Type I fibers

62
Q

In what order are muscle fibers recruited?

A
  • Type I fibers
  • Type IIA fibers
  • Type IIAX fibers
  • Type IIX fibers
63
Q

Type IIX fibers are only recruited when?

A

Recruited near maximal intensity (sprinting and jumping) and during extremely prolonged submaximal exercise.

64
Q

What are 4 factors on which the relative contribution of each pathway depends on?

A
  • Nature, intensity and duration of activity
  • Muscle fiber type composition
  • Available O2
  • Substrate composition
65
Q

Splenic contractions can cause hematocrits to rise to what percentage?

A

60-70%

66
Q

Splenic contraction can increase oxygen delivery in what 2 ways?

A
  • Increase hemoglobin

- Increase oxygen carrying capacity of the blood

67
Q

The cardiac output in a resting horse is what?

This can increase to what?

A
  • 25 L/min

- 300 L/min

68
Q

What is normal heart rate in a horse?

It can increase to a maximum of what?

A
  • 25-45 bpm

- 220-250 bpm

69
Q

Can heart rate in a horse increase rapidly or slowly?

A

Increases rapidly

70
Q

What are 3 factors that can affect stroke volume?

A
  • Myocardial contractility
  • Venous return
  • Blood volume
71
Q

What are 3 factors that can affect venous return?

A
  • Vasoconstriction
  • Muscle contraction
  • Changes in air pressure within the thorax
72
Q

Splenocontraction can contribute up to how much increased volume?

A

12 L

73
Q

What portion of cardiac output is limited in a horse?

A

Stroke volume

74
Q

An increased heart rate leads to a decreased what?

A

Decreased ventricular filling time (preload)

75
Q

How much of an increase in stroke volume is seen with submaximal exercise?
Is there any further increase with increase in exercise?

A
  • 20-50% increase

- No further increase

76
Q

Which system is the limiting factor for maximal exercise?

A

Respiratory system

77
Q

Ventilation is what rate at rest?

At exercise?

A
  • 80 L/min

- 1800 L/min

78
Q

What are 4 ways to increase tidal volume?

A
  • Increasing diaphragm contractions
  • Increasing pleural pressure changes
  • Increasing flow
  • Limit to muscular activity (energy needed to increase ventilation uses more oxygen then it delivers)
79
Q

What is a normal pleural pressure at rest?

During exercise?

A
  • 5 mmHg

- (-40 mmHg)

80
Q

What is respiration coupled with at the canter and gallop?

At what ratio?

A
  • Respiration is coupled with stride frequency

- Ratio of 1:1

81
Q

What acts as a pump when the horse is cantering/galloping?

A

Visceral contents

82
Q

When the forelegs move forward, what happens to the rib cage?

A

Rib cage is pulled forward and outward.

83
Q

When bearing weight, what happens to the rib cage?

A

Rib cage absorbs forces and is compressed.

84
Q

What can improve O2 extraction?

A

High a-v O2 gradient

85
Q

What does a high a-v O2 gradient favor?

A

Favors diffusion down concentration gradient.

86
Q

What does a right shift of O2 dissociation curve favor?

A

“Off loading”

87
Q

The ability of the horse’s muscle mass to consume oxygen far exceeds what?

A

The ability of the heart and lungs to provide oxygenated blood.

88
Q

Conditions resulting in what positively impact performance?

A

Improved cardiac output

89
Q

What is the highest percentage stroke volume can be increased by?

A

20-50%

90
Q

An extremely high heart rate can lead to what?

A

Reduced ventricular filling time.

91
Q

Hypoxemia ensues at what percentage VO2 max?

What is this due to?

A
  • 65%

- Due to diffusion limitation

92
Q

Diffusion limitations are due to what?

A

Passage of RBCs too quickly past capillaries so not fully saturated with O2.

93
Q

Respiration rate is limited to what ratio?

What max rate?

A
  • 1:1 stride to RR ratio

- Max rate: 130/min

94
Q

What are 2 limitations to ventilation?

A
  • Work of breathing very high

- Use of more O2 than it delivers

95
Q

Resistance to flow is seen more in what part of the respiratory tract?

A

Upper airway

96
Q

What are 2 limitations concerning oxygen delivery to the tissues in the respiratory system?

A
  • Resistance to flow in the upper airways

- Diffusion impairment

97
Q

What are 3 forms of compensation for reduced oxygen delivery to the tissues?

A
  • Increased oxygen carrying capacity
  • Increased heart rate
  • Increased oxygen removal at muscles
98
Q

What are 3 reasons endurance horses may become fatigued?

A
  • Glycogen depletion
  • Switching from Type I to Type II fibers
  • Can’t produce enough energy for the level of exercise
99
Q

What are 4 factors to fatigue seen with high intensity exercise?

A
  • Switching to Type IIX fibers
  • Increasing anaerobic production
  • Increasing lactate levels
  • Acidosis
100
Q

What are 2 effects of acidosis due to muscle fatigue?

A
  • Impairs glycolysis and oxidative phosphorylation, leads to decrease ATP
  • Uptake of calcium in sarcoplasmic reticulum
101
Q

Fatigue in aerobic metabolism leading to glycogen depletion occurs in what type of fibers first?
Then what type?

A
  • Occurs first in Type I

- Then IIA then IIX

102
Q

Fatigue in anaerobic metabolism is correlated with which fibers?

A

Type II fibers

103
Q

What are 5 ways in which training improves oxygen delivery?

A
  • Increase in heart mass
  • Increase in SV
  • Increase in PV
  • Increase in total RBC volume
  • Increased capillary supply to the muscles leads to increased transit time and more oxygen unloaded
104
Q

What are 2 ways blood gets redistributed?

A
  • Vasodilation to muscles and skin

- Vasoconstriction to splanchnic region and non-working muscles

105
Q

What are 5 metabolites produced by working muscles?

A
  • K+
  • H+
  • Lactate
  • CO2
  • Heat
106
Q

Redistribution of blood during exercise leads to an increase in what?

A

Increased delivery to working muscles.

107
Q

Training can lead to what 4 muscle changes?

A
  • More type IIA fibers
  • Volume of mitochondria
  • Oxidative enzymes
  • Increase in glycogen stores
108
Q

What are 2 main complaints leading to exercise evaluation?

A
  • Poor performance

- Exercise intolerance

109
Q

A demonstration of clinical problems when exercising is known as what?

A

Exercise intolerance

110
Q

What are 2 aspects to a fitness assessment?

A
  • Evaluate fitness

- Potential assessment

111
Q

What are 3 possible causes of dynamic obstructions of the airways?

A
  • DDSP
  • Dynamic pharyngeal collapse
  • Laryngeal hemiplegia
112
Q

The incorporation of what tool has lead to a decrease in the need for treadmills?

A

Newer endoscopes

113
Q

What are 2 things standard exercise tests help to assess?

A
  • Incremental exercise test

- Run to fatigue test

114
Q

When assessing athletic ability what are 2 measurements taken for heart rate?

A
  • Speed at maximum heart rate

- Speed at which heart rate of 200 is achieved

115
Q

What 2 measurements are made for lactate?

A
  • Speed at which lactate reaches 4 mmol/L

- Maximum lactate levels achieved

116
Q

What are 2 ways to evaluate the heart for performance potential?

A
  • Heart score

- Echocardiographic evaluation of hear size

117
Q

What are 3 other ways to evaluate performance potential?

A
  • Muscle biopsy
  • Inter-mandibular width
  • Treadmill testing
118
Q

Does performance rely on one characteristic or many?

A

Many

119
Q

What are 7 factors of exhaustive horse syndrome?

A
  • Protracted submaximal exercise
  • Hot weather
  • Loss of sweat (electrolytes and fluid)
  • Dehydration
  • Electrolyte disturbances
  • Hyperthermia
  • Energy depletion

LAM 1 (8 decks)

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