Chapter 3: Bioenergetics of Exercise and Training Flashcards

1
Q

Bioenergetics

A
  • The flow of energy in a biological system

- Primarily concerned with converting macros into usable forms of energy (ATP)

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2
Q

Energy

A

The capacity to do work

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3
Q

Catabolism

A
  • The breakdown of large molecules into smaller molecules

- Associated with the release of energy

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4
Q

Anabolism

A
  • The synthesis of larger molecules from smaller molecules

- Can be accomplished using the energy released from catabolism

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5
Q

Exergonic Reactions

A

Energy-releasing reactions that are generally catabolic

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6
Q

Endergonic Reactions

A

Require energy and include anabolic processes

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7
Q

Metabolism

A

The total of all catabolic/exergonic and anabolic/endergonic reactions in a biological system

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8
Q

Adenosine Triphosphate (ATP)

A
  • Composed of adenosine and three phosphates

- Potential energy in bond drives all biological work

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9
Q

Hydrolysis

A
  • The breakdown of one molecules of ATP to yield energy

- Requires one molecule of water

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10
Q

ATPase

A

Enzyme that catalyzes the hydrolysis of ATP

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11
Q

Myosin ATPase

A

The enzyme that catalyses ATP hydrolysis for crossbridge cycling

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12
Q

Calcium ATPase

A

Hydrolyzes ATP when pumping calcium into the sarcoplasmic reticulum

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13
Q

Sodium-Potassium ATPase

A

Hydrolyzes ATP to maintain the sarcolemmal concentration gradient after depolarization

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14
Q

ATP Hydrolysis

A

ATP + H2O –> ADP + Pi + H+ + Energy

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15
Q

ADP

A
  • Adenosine diphosphate

- Result of ATP hydrolysis

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16
Q

Pi

A

Inorganic Phosphate

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17
Q

AMP

A
  • Adenosine Monophosphate

- Result of ADP hydrolysis

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18
Q

3 Basic Energy Systems

A
  • Phosphagen System
  • Glycolysis
  • Oxidative System
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19
Q

Anaerobic Processes

A
  • Does not require the presence of oxygen
  • Phosphagen system
  • Glycolytic systems
  • Occur in the sarcoplasm of the muscle cell
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20
Q

Aerobic Processes

A
  • Requires the presence of oxygen
  • Krebs cycle
  • Oxidative system
  • Occur in the mitochondria of the muscle cell
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21
Q

Which macronutrient can be metabolized anaerobically?

A

Carbs

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22
Q

Phosphagen System

A
  • Drives short-term, high-intensity activities
  • Highly active at the start of activity, regardless of intensity
  • Relies on hydrolysis of ATP and breakdown of creatine phosphate/phosphocreatine
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23
Q

Creatine Kinase

A
  • Enzyme that catalyzes synthesis of ATP from CP/PCr and ADP

- ADP + CP ATP + Creatine

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24
Q

How much ATP does the body store at any given time?

A

80-100 g (not much)

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25
Q

Can ATP be completely depleted?

A

No, too important to cellular function

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26
Q

Adenylate Kinase Reaction

A
  • AKA myokinase reaction
  • 2 ADP ATP + AMP
  • Used to rapidly replenish ATP
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27
Q

Relationship between adenylate kinase reaction and glycolysis

A

This reaction acts as a stimulant for glycolysis

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28
Q

What acts as a control for the reactions of the phosphagen system?

A

Law of mass action (mass action effect)

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29
Q

Law of Mass Action (Mass Action Effect)

A
  • Concentration of reactants or products (or both) in solution will drive the direction of the reactions
  • If there’s an enzyme involved, enzyme concentration is also a major regulatory factor
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30
Q

Glycolysis

A
  • Breakdown of glucose (carbs)

- Occurs in the cytosol of the cell

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31
Q

What is the end result of glycolysis?

A

Pyruvate

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32
Q

Pyruvate may proceed in which directions?

A
  1. Can be converted to lactate in the sarcoplasm (fast/anaerobic)
  2. Can be shuttled into the mitochondria (slow/aerobic)
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33
Q

Why is glycolysis limited in duration when pyruvate is converted into lactate?

A

H+ production and the subsequent decrease in pH

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34
Q

How is the direction for pyruvate determined?

A

The energy demands of the cell

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35
Q

What enzyme catalyzes the formation of lactate from pyruvate?

A

Lactate dehydrogenase

36
Q

Does lactic acid form as the result of anaerobic glycolysis?

A

NO

37
Q

Does lactate cause fatigue?

A

NO

38
Q

What causes fatigue?

A
  • Proton (H+) accumulation

- H+ interferes with muscle’s excitation/contraction coupling (possibly inhibiting the binding of calcium)

39
Q

Metabolic Acidosis

A
  • Exercise-induced decrease in pH

- May be partially responsible for peripheral fatigue occurring during exercise

40
Q

Cori Cycle

A

Process by which lactate is delivered to the liver, where it is converted into glucose

41
Q

Net Reaction of Glycolysis –> Lactate

A

Glucose + 2Pi + 2ADP –> 2 Lactate + 2ATP + H2O

42
Q

Net Reaction of Glycolysis –> Pyruvate

A

Glucose + 2 Pi + 2 ADP + 2 NAD+ –> 2 Pyruvate + 2 ATP + 2 NADH + 2 H2O

43
Q

2 Primary Mechanisms for ATP Resynthesis

A
  • Substrate-level phosphorylation

- Oxidative phosphorylation

44
Q

Substrate-level Phosphorylation

A

Refers to the direct resynthesis of ATP during a single reaction

45
Q

Oxidative Phosphorylation

A

Refers to the resynthesis of ATP in the electron transport chain

46
Q

Phosphofructokinase (PFK)

A
  • The enzyme that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-biphosphate
  • Rate-limiting step
47
Q

Glycogenolysis

A

The process of breaking down muscle glycogen

48
Q

Glycogen Phosphorylase

A

The enzyme that catalyzes the breaking down of muscle glycogen

49
Q

What factors stimulate glycolysis?

A
  • High concentration of ADP, Pi, and ammonia

- Slight decrease in pH and AMP

50
Q

What factors inhibit glycolysis?

A

Markedly lower pH, ATP, CP, citrate, and free fatty acids

51
Q

3 enzymes which are critical for regulating glycolysis

A
  • Hexokinase
  • PFK
  • Pyrivate kinase
52
Q

Allosteric Regulation

A

Occurs when the end product of a reaction or series of reactions feeds back to regulate the turnover rate of key enzymes in the metabolic pathways

53
Q

Allosteric Inhibition

A

When an end product binds to the regulatory enzyme and decreases its turnover rate and slows product formation

54
Q

Allosteric Activation

A

When an activator binds with the enzyme and increases its turnover rate

55
Q

Hexokinase

A
  • Catalyzes the phosphorylation of glucose to glucose-6-phosphate
  • Allosterically inhibited by concentration of glucose-6-phosphate in the sarcoplasm
56
Q

Lactate Threshold

A
  • An abrupt increase above the baseline concentration of blood lactate
  • Represents a significant dependence on anaerobic mechanics for energy production
  • Corresponds well with the ventilatory threshold
  • Often used as a marker of the anaerobic threshold
57
Q

When does LT occur in untrained individuals?

A

At ~50-60% of VO2max

58
Q

When does LT occur in aerobically trained individuals?

A

At ~70-80% of VO2max

59
Q

Onset of Blood Lactate Accumulation (OBLA)

A
  • An increase in the rate of lactate accumulation at higher relative exercise intensities
  • 4 mmol/L
60
Q

What substrates does the aerobic system use for energy?

A

Carbs and fats (not proteins)

61
Q

Beta Oxidation

A
  • A series of reactions in which free fatty acids are broken down
  • Results in the formation of acetyl-CoA and H+
  • Acetyl-CoA enters Krebs cycle and H+ is carried by NADH and FADH2 to the ETC
62
Q

Contribution of protein to metabolism

A
  • Negligible during short exercise

- 3-18% of energy demands during prolonged activity

63
Q

Branched-chain Amino Acids

A
  • The major amino acids that are oxidized in skeletal muscle
  • Leucine, isoleucine, and valine
  • Alanine, aspartate, and glutamate may also be used
64
Q

Rate-limiting step for Kreb cycle

A

Conversion of isocitrate to alpha-ketoglutarate (catalyzed by isocitrate dehydrogenase)

65
Q

Energy System for Activities 0-6 seconds

A

Intensity of Event: Extremely high

Primary Energy System Used: Phosphagen

66
Q

Energy System for Activities 6-30 seconds

A

Intensity of Event: Very high

Primary Energy System Used: Phosphagen and fast glycolysis

67
Q

Energy System for Activities 30 s to 2 min

A

Intensity of Event: High

Primary Energy System Used: Fast glycolysis

68
Q

Energy System for Activities 2-3 min

A

Intensity of Event: Moderate

Primary Energy System Used: Fast glycolysis and oxidative system

69
Q

Energy System for Activities >3 min

A

Intensity of Event: Low

Primary Energy System Used: Oxidative system

70
Q

Glycogen stores in the body

A
  • 300-400 g in muscle

- 70-100 g in the liver

71
Q

Bioenergetic Limiting Factors

A
  • ATP and CP
  • Muscle glycogen
  • Liver glycogen
  • Fat stores
  • Lower pH
72
Q

ATP and CP are limiting factors for activities such as?

A

High intensity, short duration exercises like the 100 m run or Olympic weightlifting

73
Q

Muscle glycogen is a limiting factor for activities such as?

A
  • Marathon or triathalon

- Weightlifting

74
Q

Liver glycogen is a limiting factor for activities such as?

A

Low intensity, long duration exercises like a marathon or triathalon

75
Q

Fat stores is a limiting factor for activities such as?

A

Not much, the activity it has the most impact on is a marathon

76
Q

Lower pH is a limiting factor for activities such as?

A

Longer duration, high intensity activities like a 400 m run or Olympic weightlifting

77
Q

Oxygen Deficit

A
  • The aerobic system responds slowly to exercise, so anaerobic systems fuel exercise initially
  • The anaerobic contribution to the total energy cost of exercise
78
Q

Oxygen Debt

A
  • After exercise, oxygen uptake remains above preexercise levels for a time according to the length and intensity of the exercise
  • AKA Recovery O2 or Excess Postexercise Oxygen Consumption (EPOC)
79
Q

Interval Training

A

A method that emphasizes bioenergetic adaptations for a more efficient energy transfer within the metabolic pathways by using predetermined intervals of exercise and work periods

80
Q

Work-to-Rest Ratios

A

Predetermined intervals of exercise and rest periods

81
Q

High-Intensity Interval Training (HIIT)

A

Involves brief repeated bouts of high-intensity exercise with intermittent recovery periods

82
Q

Variables of HIIT

A
  • Intensity of the active portion of each duty cycle
  • Duration of the active portion of each duty cycle
  • Intensity of the recovery portion of each duty cycle
  • Duration of the recovery portion of each duty cycle
  • Number of duty cycles performed in each set
  • Number of sets
  • Recovery intensity between sets
  • Mode of exercise for HIIT
83
Q

Interval training profile for 90-100% of max power

A
  • Primary System Stressed: Phosphagen
  • Typical Exercise Time: 5-10 s
  • Range of Work-to-Rest Period Ratios: 1:12 to 1:20
84
Q

Interval training profile for 75-90% of max power

A
  • Primary System Stressed: Fast glycolysis
  • Typical Exercise Time: 15-30 s
  • Range of Work-to-Rest Period Ratios: 1:3 to 1:5
85
Q

Interval training profile for 30-75% of max power

A
  • Primary System Stressed: Fast glycolysis and oxidative
  • Typical Exercise Time: 1-3 min
  • Range of Work-to-Rest Period Ratios: 1:3 to 1:5
86
Q

Interval training profile for 20-30% of max power

A
  • Primary System Stressed: Oxidative
  • Typical Exercise Time: >3 min
  • Range of Work-to-Rest Period Ratios: 1:1 to 1:3
87
Q

Combination Training

A
  • AKA cross-training
  • A style of training where aerobic endurance training is added to the training of anaerobic athletes
  • Thought to improve recovery, since it is thought recovery relies on aerobic mechanisms