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Exercise Physiology > Final Study Questions > Flashcards

Final Study Questions Flashcards

1
Q

Write the ATPase Equation -

A

ATP —> ADP + Pi + Energy + Heat

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2
Q

What is a rate- limiting enzyme and why does every metabolic pathway have rate-limiting enzymes? What stimulates a rate- limiting enzyme? -

A

The enzyme that catalyze the reaction of the rate limiting step. The activity of the rate limiting enzyme is regulated, in part, by modulators within the cell such as the concentrations of ATP, ADP, and Pi

  • They are usually found near the beginning of a series of reactions which is also known as a metabolic pathway
  • Many of the modulators operate on a negative feedback system
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3
Q

How many calories are released from the breakdown of ATP -

A

7.3 kcal in the lab

12 kcal in normal cell, pH, and temp.

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4
Q

Does skeletal muscle store small or large amounts of ATP? Explain why -

A

Small amounts (2-4g/kg muscle)

  • too much can’t be stored in the cell because it’s such a big molecule compared to the substrates (not enough room in the cell), instead it’s resynthesized
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5
Q

Name the different metabolic pathways that resynthesize ATP -

A
  1. Anaerobic Glycolysis
  2. Aerobic Glycolysis
  3. Beta Oxidation of Fats
  4. ATP-CrP system
  5. Protein Metabolism
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6
Q

What energy substrate is used by each of the metabolic pathways

a) ATP -CrP System
b) Anaerobic Glycolysis
c) Aerobic Glycolysis
d) Beta Oxidation of Fats -

A

a) creatine phosphate
b) glucose
c) glucose
d) triglycerides (stored in adipose tissue)

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7
Q

Which metabolic pathways are aerobic? Which are anaerobic? -

A

Aerobic: aerobic glycolysis, beta oxidation of fats

Anaerobic: anaerobic glycolysis, ATP-CrP

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8
Q

Why is it necessary to resynthesize ATP in every cell? -

A
  • ATP is unable to cross the cell membrane

- It can’t be transported into a cell from blood or another cell

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9
Q

Explain the physiological benefits for having so many metabolic pathways designed to resynthesize ATP -

A
  • Differing rates and amounts from each pathway

- Depending on the demand for either large amounts of ATP or rapid ATP, the body will use different pathways

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10
Q

Explain the functional benefits for having so many metabolic pathways designed to resynthesize ATP -

A
  • Allows us to engage in physical activity of a wide range of intensities and durations
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11
Q

Know the enzyme in the ATP-Pc system -

A

Creatine Kinase

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12
Q

What is the creatine kinase reaction -

A

ADP + CP -> ATP + C

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13
Q

What is meant by identifying the 2 reactions in the ATP-Pc system as coupled? -

A

The energy released from one reaction is used in the second reaction to synthesize ATP

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14
Q

If the ATP-PC system was the only metabolic pathway available, how long would it be able to meet the needs of maximal intensity exercise? -

A

15 seconds

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15
Q

Is creatine supplementation always effective? -

A

No.

- Some people respond to the supplementation while others don’t

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16
Q

For what type of training would creatine supplementation be effective? -

A

Short Duration, High Intensity

  • Weight Lifting or Sprinting
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17
Q

What is the loading and maintenance dose of creatine (as suggested on the package)? -

A

Loading phase: 5 days- 20 g/day

Maintenance phase: however long you want to take it, 2-3 g/day

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18
Q

What dose of creatine is recommended by the scientific literature? -

A

Loading: .3 g/kg/day
Maintenance: .03 g/kg/day

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19
Q

Name the Catabolic Metabolic Pathways -

A
  1. Glycogenolysis/Lipolysis
  2. Anaerobic/Aerobic Glycolysis
  3. Beta Oxidation
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20
Q

Name the Anabolic Metabolic Pathways -

A
  1. Glycogenesis
  2. Gluconeogenesis
  3. Lipogenesis
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21
Q

What is the chemical formula for glucose? -

A

C6H12O6

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22
Q

How does glucose enter the skeletal muscle cell? -

A

Through Glu4 Transporter

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23
Q

After glucose enters the skeletal muscle cell and is phosphorylated, what 2 things can happen to it? -

A
  1. Undergo Glycolysis: Breakdown to pyruvate

2. Undergo Glycogenesis: Stored as glycogen

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24
Q

Where is glycogen stored in the body? -

A

Liver and skeletal muscle

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25
Q

What is different about glycogen stored in the liver vs. glycogen stored in skeletal muscle? -

A
  • In the liver it can undergo glycogenolysis and be transported from the liver to maintain blood glucose levels, but in the skeletal muscle it can’t
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26
Q

What is the preferred energy substrate? Explain why -

A

CHO

  • Glycogen is stored in the skeletal muscle cell and is readily available source of energy
  • Glucose and glycogen can be metabolized either aerobic/ anaerobically
  • Aerobic metabolism of CHO produces more ATP per O2 consumed than fat metabolism
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27
Q

The duration of submaximal aerobic exercise that can be sustained without fatiguing is dependent, in part, on what factor? -

A

Lactate Threshold

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28
Q

What is the purpose of liver glycogenolysis? -

A

The liver contains the enzyme required to convert G6P to Glucose

  • This allows the liver glycogen to be used in maintaining blood glucose levels
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29
Q

What metabolic processes are used to help maintain blood glucose levels during exercise? -

A
  • Liver Glycogenolysis

- Lipolysis

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30
Q

What else can be done to help maintain blood glucose levels during exercise? -

A

Eating and Drinking

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31
Q

Where is fat that is used to fuel skeletal muscle metabolism stored in the body? -

A
  • In the adipose tissue (this is the most plentiful source)
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32
Q

What is lipolysis, and where does it occur? -

A

Breakdown of triglycerides to glycerol and 3 fatty acids

  • The liver (adipose tissue)
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33
Q

What is beta oxidation and where does it occur? -

A

Breakdown of Fatty Acids into two carbon units

- The Mitochondria

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34
Q

How does lipolysis contribute to maintaining blood glucose levels? -

A

The glycerol molecule is transported through the blood into the liver where it undergoes gluconeogenesis (formation of glucose in the liver)

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35
Q

Name 4 ways which blood glucose levels can be maintained: -

A
  1. Liver Glycogenolysis
  2. Liver Gluconeogenesis of Lactate
  3. Liver Lipolysis (Glycerol -> Glucose)
  4. Liver Amino Acids
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36
Q

What is the first thing that happens to glucose after it enters the muscle cell? Where does the phosphate come from? -

A

1st thing: It’s immediately phosphorylated to G6P (a loss of one ATP)
- The phosphate comes from an ATP

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37
Q

Explain why glycogen stored in the muscle cell cannot be used to maintain blood glucose levels -

A
  • because it’s stored in the muscles and not from the liver
  • Liver glycogenolysis maintains blood glucose within a normal range
  • In the muscle cell, glycogenolysis is incomplete in that G6P is not completely converted to glucose
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38
Q

How many total ATP are resynthesized from glucose in anaerobic glycolysis? -

A

2

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39
Q

How many net ATP are resynthesized from glycogen in anaerobic glycolysis? -

A

3

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40
Q

Explain substrate level phosphorylation -

A

The phosphates needed to resynthesize ATP from ADP come directly from the substrate, or intermediate in the metabolic pathway
- All 4 ATP are formed by this

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41
Q

What is the rate-limiting enzyme of anaerobic glycolysis? -

A

Phosphofructokinase (PFK)

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42
Q

What is the metabolic end product of anaerbobic glycolysis? -

A

lactate

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43
Q

What is the enzyme that is involved in the reduction of pyruvate to lactate? -

A

Lactate dehydrogenase (LDH)

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44
Q

Explain why there are two pyruvates (and two lactates) that result from glycolysis of one glucose -

A

Pyruvate is reduced to lactate as it accepts the two hydrogens carried by NAD+. The NADH + H+ is oxidized to NAD+ because it loses the two hydrogens and accompanying electrons

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45
Q

Describe the difference between the production and accumulation of lactate -

A

The accumulation of lactate occurs when the production of lactate exceeds the disposal of lactate

  • can occur due to an increase in production, decrease in removal, or both
  • Lactate Production increases during exercise because of
  1. limitations in the delivery of O2 to and the utilization of O2 in the mitochondria that increase rate of anaerobic glycolysis within muscle fibers that are already recruited, and
  2. Increase recruitment of type II motor units (that are highly glycolytic)
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46
Q

When is lactate produced? -

A

It is an inevitable product of anaerobic glycolysis

- It is ALWAYS being produced but increases as the intensity of exercise increases

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47
Q

If anaerobic glycolysis was the only metabolic pathway available, how long would it be able to meet the needs of maximal intensity exercise? -

A

About 1-3 minutes

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48
Q

How (and where) is lactate ‘removed’? -

A
  1. Oxidized to Pyruvate and used in KREBS (intracellucar)
  2. Shuttled to other skeletal muscle cells and there oxidized to Pyruvate
  3. Transported in the blood and consumed by the heart. Also oxidized to Pyruvate here
  4. Carried by blood to the liver to undergo Gluconeogenesis
  5. Small amounts excreted through skin and urine
  6. Some remains in blood to maintain normal lactate level and pH
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49
Q

How does lactate result in fatigue? -

A

When lactate is produced, so are hydrogen ions. When more hydrogen ions are present than the buffer capacity, the pH of the skeletal muscle will decrease and low pH interferes with optimal contractile processes
- The theory that lactate per se directly causes fatigue hasn’t been well accepted

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50
Q

What are the physiological benefits of anaerobic glycolysis and the production of lactate? -

A

Physiological Benefits:

  • A large # of activities can be performed above and beyond those that could be sustained by the ATP-PC system alone
  • The final step allows more pyruvate to be reduced to lactate during high-intensity exercise. This allows ATP to be resynthesized anaerobically at high rate rather than relying solely on aerobic metabolism to meet the metabolic demand of the exercise

Lactate production:

  • lactate produced in one muscle cell can be an energy substrate in another cell
  • Due to its contribution to the Bohr Effect. The increase in H+ and the decrease in pH helps reduce the affinity of O2 for Hb
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51
Q

What are the three factors that differentiate aerobic performance between individuals? -

A
  1. VO2 Max
  2. Performance VO2
  3. Economy of Movement
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52
Q

What is the name of the phenomenon that occurs when there is an increase rate of lactate accumulation? -

A

Lactate Threshold

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53
Q

Functionally, what is the LT or MLSS trying to predict? -

A

Changes in lactate concentration due to training (or detraining)

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54
Q

How is performance VO2 calculated? -

A

The product of VO2 max and the % VO2max at which the LT, CP, or MLSS occur

VO2max (ml/kg/min) * %VO2 max at LT, CP, or MLSS = Performance VO2 (ml/kg/min)

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55
Q

Explain why the LT and MLSS are measures of ‘aerobic’ performance.

A
  • They are used to develop an effective training program designed to improve aerobic performance
  • Provide a physiological basis for determining a race pace for endurance events
  • and can be used to monitor the effects of training
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56
Q

What are the 4 stages of aerobic glycolysis? -

A
  1. Glycolysis
  2. Decarboxylation of Pyruvate
  3. KREBS Cycle
  4. Electron Transport System
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57
Q

What is the enzyme that is involved in the decarboxylation of pyruvate? -

A

Pyruvate Dehydrogenase (PDH)

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58
Q

In which stages of aerobic glycolysis does substrate level phosphorylation occur? -

A 
Stage 1 (cytoplasm)
Stage 3 (Krebs Cycle)
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59
Q

Where in the cell does oxidative phosphorylation occur?

A

Only in the mitochondria, specifically in the ETS

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60
Q

Which stage is characterized by oxidative phosphorylation? -

A

Stage 4 (ETS)

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61
Q

How many net ATP are resynthesized from aerobic glycolysis? -

A

36

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62
Q

What is the role of NAD and FAD? -

A

Transport hydrogens and electrons to the ETS (stage 4). This is a chain of reactions in the mitochondria that passes electrons through a sequence of reactions. In the final step, O2 accepts the hydrogens and electrons

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63
Q

In the aerobic glycolysis of glucose, how many ATP come from substrate-level phosphorylation? How many ATP come from oxidative phosphorylation? -

A

Substrate-level phosphorylation: 4

Oxidative phosphorylation: 32

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64
Q

What is one likely limiting factor to the rate of ATP resynthesis in aerobic glycolysis

  • What most likely contributes to this limiting factor (delivery and utilization of O2) -
A

The delivery and utilization of oxygen

  • One likely limiting factor: Oxidative phosphorylation occurs only in the ETS of the mitochondria
  • What contributes: The mount of ATP formed is dependent on how many hydrogens are dropped off in the ETS
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65
Q

If aerobic glycolysis was the only metabolic pathways available, how long would it be able to meet the needs of submaximal intensity aerobic exercise -

A

Several hours, depending on intensity and availability of substrates

66
Q

Which is a more efficient user of CHO, aerobic or anaerobic glycolysis? -

A

Aerobic: 38%

Anaerobic: 2%

67
Q

What is beta oxidation? -

A

A series of reactions that results in the cleavage of 2-carbon units from the long carbon chain (i.e. the breaking of 2-carbon units off of a long even # carbon chain FA)

68
Q

Where does beta oxidation take place? -

A

In the mitochondria

69
Q

How do the carbon structures from a fat enter the metabolic pathway? -

A

Through Lipolysis, by carnitine transferase

70
Q

Where do the carbon structures from a fat enter the metabolic pathway? -

A

In the mitochondrial matrix (mitochondria)

71
Q

How many net ATP are derived from a 16-C FA? -

A 
16-C FA
16/ 2 = 8 Acetyl CoA
7: # of breaks
7 x 5 = 35
8 x 12 = 96
35 + 96 = 131-2 = 129
Net ATP: 129 ATP
72
Q

What happens to the glycerol that is formed during lipolysis? -

A

Most of the glycerol goes to the liver where it’s converted to glucose (gluconeogenesis) to be used by CNS or active skeletal muscle during exercise

73
Q

How many ATP are resynthesized from substrate-level phosphorylation from a 16-C FA? -

A

1 ATP

74
Q

Which is a more efficient use of oxygen, carbohydrates or fats? -

A

Carbohydrates

75
Q

Name two sources of carbohydrate available to the muscle during exercise: -

A

Triglycerides and Glycogen

76
Q

Name the 2 sources of fat available to the muscle during exercise: -

A

Fatty Acids and Glucose

77
Q

With respect to metabolism, what is the role of the hormonal responses to exercise? -

A

They are responsible for controlling the availability of energy substrates

78
Q

What is the fastest modulator to stimulate rate-limiting enzymes? -

A

Changes in the concentrations of ATP, ADP, Pi, and the ATP/ADP ratio are the 1st and most rapid mechanisms for activating enzymes in the metabolic pathway

79
Q

Why does exercise have an insulin-like effect? -

A

Exercise, like insulin, causes an increase in glucose uptake by skeletal muscle

  • Membrane becomes more permeable to glucose
80
Q

Insulin -

A

Actions:
increase permeability of cell to glucose (except liver, kidney, and brain), thereby increasing glucose uptake by cells, inhibits lipolysis (-HSL) and increase lipogenesis, increase amino acid uptake, increase glycogenesis, inhibits glycogenolysis, inhibits gluconeogenesis

Exercise response: decreases, inhibited by NE

81
Q

Know the metabolic responses to each of the following hormones and how the hormones respond to exercise(increase or decrease):
NE -

A

Actions:
Activates metabolic enzymes to increase glycogenolysis, increase gluconeogenesis, increase lipolysis (+HSL), increase release of glucagon, inhibits release of insulin
Exercise response: increases

82
Q

Know the metabolic responses to each of the following hormones and how the hormones respond to exercise(increase or decrease):
Glucagon -

A

Actions:
Increase liver glycogenolysis, increase gluconeogenesis, increase lipolysis
Exercise response: Increase

83
Q

Know the metabolic responses to each of the following hormones and how the hormones respond to exercise(increase or decrease):
Cortisol -

A

Actions:
Increase lipolysis, increase gluconeogenesis, increase glycogenolysis, increase protein catabolism, reduces glucose uptake
Exercise response: increase

84
Q

How does growth hormone help regulate blood glucose levels? -

A
  • the stimulation of gluconeogenesis in the liver by GH provides long-term control of blood glucose
  • stimulates lipolysis, thereby increase the availability of FA as energy substrate
  • retards the entry of blood glucose into cell, thereby sparing blood glucose and increase the rate of FA utilization
  • increase the uptake of AA
  • maintaining blood glucose levels is important in sparing of carbohydrate sources during prolonged periods of aerobic exercise
85
Q

How does cortisol help regulate blood glucose levels? -

A
  • Stimulates lipolysis in adipose tissue and glycogenolysis and gluconeogenesis on liver which increase the availability of FA and blood glucose
  • increase the breakdown of proteins to amino acids by inhibiting the synthesis of protein. Amino Acids -> glucose in liver
  • retards entry of glucose into cell, forcing the cell to use more FA as energy substrate. Spares blood glucose and increase the rate of utilization
86
Q

Name 4 ways that blood glucose levels can be maintained during exercise: -

A
  • Liver Glycogenolysis
  • The Gluconeogenesis of lactate, glycerol, and amino acids in the liver
  • The reduced enrty of glucose into the cell caused by the increase in GH and Cortisol
  • The consumption of carbohydrate drinks
87
Q

Define predominant energy system -

A

The one metabolic pathway that most closely matches the total energy needs of the body

88
Q

Discuss the principles that form the basis of the concept of the predominant energy system: -

A
  • All energy systems (metabolic pathway), both aerobic and anaerobic, contribute to the total energy needs of the body at any given time
  • The sum of the contributions of all the energy systems is equal to the total energy needs of the exercise
  • Conceptually, at any given time, there is one predominant energy system that provides the majority of the required ATP at the appropriate rate. The balance of the total energy demand that is not met by the predominant energy system is met by the other energy systems.
89
Q

Rank the Metabolic Pathways according to rate and amount -

A

Rate (High to Low): ATP-PC, Anaerobic Glycolysis, Aerobic Glycolysis, Beta Oxidation

Amount (High to Low): Beta Oxidation, Aerobic Glycolysis, Anaerobic Glycolysis, ATP-PC

90
Q

What is given up in order to increase the rate of ATP resynthesis? -

A

The amount of ATP produced

91
Q

Why is CHO the preferred energy substrate -

A
  1. More O2 efficient
  2. More readily available (glycogen and blood glucose enter cell easier than fat)
  3. Can be utilized Aerobic/Anaerobically
92
Q

What factors determine the predominant energy system during exercise? -

A
  1. Intensity of exercise (most important)
  2. Duration of exercise
  3. Training status of individual
  4. Availability of substrates
93
Q

What are the limitations of each of the metabolic pathways that might contribute to fatigue? -

A
  • ATP-PC system: Amount of CrP in cell
  • Anaerobic Glycolysis: Lactate accumulation
  • Aerobic Glycolysis: Availability of CHO
  • Beta Oxidation of Fats: Availability of CHO (Not availability of Fat)
94
Q

What are the 5 factors that typically contribute to exercise-induced fatigue? -

A
  1. Depletion of CrP
  2. Accumulation of Lactate
  3. Hypoglycemia
  4. Depletion of Muscle Glycogen
  5. Dehydration
95
Q

Given an example of a particular exercise and be able to name the predominant energy system and the likely cause(s) of fatigue of that exercise -

A

Exercise: 1 RM Bench Press
Predominant Energy System: ATP-PC
Causes of Fatigue: Depletion of CrP

96
Q

Draw the energy expenditure graph and describe the resting metabolic rate, oxygen deficit period, steady-state period, and the total energy expenditure. -

A

Look in notebook for picture

  • Resting Metabolic Rate (REE): A steady-state condition that is equivalent to 1 MET
  • Oxygen Deficit Period: When needs of the body can’t be met by aerobic metabolism occurs at onset of exercises, occurs when intensity of exercise increases, its a relative deficit (relative to the amount of O2 that would be consumed if O2 demands were being met aerobically)
  • Steady State VO2: Period of time (at rest or during exercise) during which energy demands are constant and aerobic energy systems meet most of the energy demands of the body
  • Total Energy Expenditure (TEE): The sum of contributions of all of the metabolic pathways
97
Q

What is the average value for resting energy expenditure? -

A

3.5 ml/kg/min = 1 MET

98
Q

If Susan (70 kg) has a resting energy expenditure of 1 MET, how many calories does she expend while watching a 2 hour movie? What is her VO2 in mL/kg/min? What is her VO2 in L/min? -

A

1 MET x 1.05 kcal/kg/hr x 70 kg x 2 hr = 147 kcal

VO2 = 1 MET = 3.5 ml/kg/min

VO2 = 3.5 ml/kg/min x 70 kg/1000 = .245 L/min

99
Q

Why does it take about 3 min to reach a steady-state after exercise starts? -

A
  • It’s the time that takes for VO2 o increase from resting value to a steady-state
  • There are a lot of things that need to happen: increase sympathetic, increase muscle units, etc.
  • Other physiological systems must respond to the onset of exercise
100
Q

What are the 2 time periods in which a steady-state exists? -

A
  • at rest

- After the period of O2 deficit/ during low-moderate intensity exercise

101
Q

Under what circumstances does an O2 deficit occur? -

A

When there is relatively insufficient supply of oxygen to the cell due to the lag in the cardiovascular responses to the onset of exercise or when intensity of exercise increases

102
Q

Describe how the energy needs of the body are met during the oxygen deficit period: -

A
  • Aerobic pathways are becoming the predominant energy system. However, there is a large contribution from anaerobic pathways to make up the difference during this period
103
Q

Describe how the energy needs of the body are met during steady state: -

A

There is a small gap between the aerobic line of the graph and the total, meaning that some of the energy expenditure is still from anaerobic pathways, though the amount is very small

104
Q

What is the R, RQ, or RER? -

A

It’s an indicator of the contribution of energy substrates during steady state

  • RQ = Respiratory Quotient = The name of the ratio VCO2/VO2
  • RER: Resting energy expenditure/ ratio: VCO2/VO2
105
Q

How is RER calculated? -

A

RER (Respiratory Exchange Ratio) = VCO2/VO2

- Measured at the mouth using a metabolic chart in lab

106
Q

What information can be determined if the RER is known? -

A

% of energy expended from fats and CHO, and the caloric equivalent (kcal/ LO2)

107
Q

What 3 assumptions are made if the RER table is used to calculate energy expenditure? -

A
  1. Contribution of Protein is negligible
  2. Your in steady-state
  3. Anaerobic contribution is negligible
108
Q

What is the caloric equivalent? -

A

The energy expended from each liter oxygen that is consumed (kcal/LO2)

109
Q

Explain how intensity of exercise affects RER: -

A

As intensity of exercise increases, there is an increase in the utilization of CHO and a decrease in the utilization of fats

110
Q

Explain how intensity of exercise affects the caloric equivalent -

A
  • The caloric equivalent increases
  • CHO are more O2 efficient. Since this is the case, the greater the intensity, the more CHO is utilized and the caloric equivalent increases
111
Q

Explain how intensity of exercise affects the contribution of CHO and Fats: -

A

Less fats are used and more carbs are used as exercise increases

112
Q

Why does the caloric equivalent increase as the intensity of exercise increases? -

A
  • The energy expended to oxygen consumed ratio is higher
  • This is because the harder you exercise, the more O2 you are consuming, hence the more kcal expended because more liters of O2 are bing consumed
113
Q

It is common knowledge that as the intensity of exercise increases, the amount of energy expended increases. Explain why. -

A
  • Energy Expenditure increases because VO2 and Caloric Equivalent increases
  • Rate of ATP Synthesis
  • Hormonal response to exercise (this is the reason there are less fats being used. Decreased Hormones, Decrease Lypolysis-breakdown of fats)
  • There is an increase in the efficiency of carbs, which is an increase in kcal (energy expenditure)
114
Q

be able to calculate energy expenditure (kcal/min) given VO2 and RER or METS, or just VO2 -

A

Ex. 30 min, 80 kg, VO2: 30 ml/kg/min, RER: 0.90 (caloric equivalent: 4.924)
-Method 1:
30 ml/kg/min x 80 kg / 1000 ml/L = 2.4 L/min
2.4 L/min x 4.924 kcal/L = 11.8 kcal/min
11.8 kcal/min x 30 min = 354 kcal
CHO = 66% x 354 = 233 kcal
FAT = 34% x 354 = 120 kcal

  • Method 2:
    RER: unknown (caloric equivalent = 5 kcal/L)
    2.4 L/min x 5 kcal/L = 12 kcal/min
    12 kcal/min x 30 min = 360 kcal for 30 min
  • Method 3:
    1 MET = 3.5 ml/kg/min, 1.05 kcal/kg/hr
    30 (ml/kg/min) / 3.5 ml/kg/min = 8.57 MET
    8.57 METs x 1.05 kcal/kg/hr x 80 kg = 720 kcal/hr
    720 kcal/hr x 0.5 hr = 360 kcal
115
Q

Explain the crossover concept and understand its relationship to the RER table -

A
  • As intensity increases, usage of CHO increases, and fats decrease
  • Usage of CHO and FAT are inversely related. This gives the X on the graph and shows the crossover of the predominant energy substrate from FAT to CHO as RER increases
116
Q

Based on the RER table and the crossover concept, what is the recommended exercise program to lose weight (body fat) -

A

Low intensity and long duration

117
Q

Provide a rationale for low-intensity and long-duration exercise to lose body weight (fat) -

A
  • at low intensity a greater % of energy expended will come from fat. However, long duration is necessary so that significant amount of energy will be expended
  • provides greatest % of total calories from fat, prolonged durations necessary for increase TEE
118
Q

What are the disadvantages of the low-intensity, long-duration concept to lose to lose body weight (body fat)? -

A
  • there may not be a significant fitness benefit since the low intensity isn’t meeting the minimum guideline of moderate intensity.
  • TEE and TEE from fats is low, since load of light, little overload and physical fitness improvements
119
Q

Based on the MFO, what is the recommended exercise program to lose weight (body fat)? -

A
  • right at the cross over point (exercise at moderate intensity)
  • moderate intensity above the crossover but below the LT (because lactate hinders lipolysis)
120
Q

What are the 3 benefits of doing moderate-intensity, moderate-duration aerobic exercise (instead of low-intensity, long-duration exercise)? -

A
  • VO2, Caloric Equivalent, TEE higher (if close to MFO total contribution of fats will be higher provides overload)
  • increases fitness benefit, less time, still expending a good % of energy from fat
121
Q

How does intensity of exercise influence the use of muscle glycogen? -

A
  • The higher the intensity the higher % of energy expanded from glycogen
  • Type 2 recruitment
  • A readily available source of energy for high intensity exercises EPI increases as muscle glycogen utilization as the intensity of exercise increases (PI stimulates phosphorylase A which breaks down glycogen in the EPI-Cyclic AMP)
122
Q

In what situations would carbohydrate-loading be appropriate prior to an event? -

A
  • When the event is going to be higher intensity than the cross over point
  • “It’s the most appropriate and successful before continuous competitive endurance events lasting 90 min. or longer”
  • Not appropriate prior to normal training day, games or most sporting events (pregame meals can usually handle it)
123
Q

Explain how duration of exercise affects the use of different energy substrates -

A

Increased duration causes increase use of plasma free FA and blood glucose, but decrease use of muscle triglycerides and muscle glycogen

124
Q

Review what hormonal responses result in an increased availability of plasma fatty acids as the duration of exercise increases. -

A
  • Increase lipolysis in adipose tissue NE GH glucagon and cortisol
  • NE and EPI stimulated glycogenolysis in liver and muscles and lipolysis
  • Glucagon: stimulates lipolysis
  • Insulin decreases thus increases lipolysis glycogenolysis and gluconeogenesis
  • Growth Hormone: lipolysis in adipose tissue and retards blood glucose entry
125
Q

Review how blood glucose levels are maintained as the duration of exercise increases and the use of blood glucose increases -

A
  • Liver glycolysis and gluconeogenesis and carbohydrate consumption can support rate of blood glucose utilization
  • Hormonal repsonses cause the blood glucose to be maintained by glycogenolysis and gluconeogenesis. Skeletal muscle membranes are more permeable to glucose causing blood glucose to be used more
126
Q

Describe generally what occurs during the time period called EPOC -

A

EPOC (Excessive post exercise O2 consumption): The time after exercise when the energy expenditure is still elevated and the physiological systems return to resting steady state

127
Q

Describe what occurs during the fast phase and the slow phase of EPOC: -

A

Phase 1:
Fast phase (2-3 min)
O2 levels of myoglobin is restored
CrP is resynthesized

Phase 2:
Slow phase (30 min.- several hours)
clears out lactate
body temperature regulation
removes hormones
128
Q

What is the rationale for why we promote an active cooldown following exercise? -

A

To help maintain blood flow that can…

  1. Help regulate temp.
  2. Remove metabolic byproducts
  3. Replenishes energy substrates
129
Q

Describe the various effects of dehydration on performance -

A
  • 2% of body weight affects aerobic performance
  • decrease blood volume -> decrease SV -> decrease Q and MAP -> decrease O2
  • increase body temp.
  • 3-4% impairs anaerobic performance (inhibits perfusion of blood into skeletal muscle)
  • increase lactate levels
  • increase muscle temperature
  • Degrades muscle glycogen
  • decrease cognitive function
  • iincrease RPE (Rate of Percieved Exertion)
  • decrease motivation to exercise
  • decrease time to exhaustion
  • comprise physiological function and negatively affect performance
130
Q

Know the dietary recommendations for CHP (carbohydrates), FAT, and PRO consumption for American adults -

A

CHO: 50-60% of Total kcal (45-65%)
FATS: Less than 30% (20-35%)
PRO: 10-20% or .8 g/kg (10-35%)

131
Q

Describe the 4 dietary things that can be done before exercise that can improve training performance -

A
  1. Consuming a high carbohydrate diet
  2. Carbohydrate loading
  3. Pregame meal
  4. Fluid and carbohydrate consumption between pregame and exercise bout
132
Q

How much CHO should an athlete consume in a high-CHO diet? why is a high-CHO diet necessary? -

A
  • 500g is needed
  • 60-70% total caloric intake
  • helps prevent protein catabolism
  • helps prevent release of stress hormones, cortisol and catecholamines
  • immune system compromises
  • high-CHO diet necessary to prevent insuffiecient replenishment of muscle and liver glycogen during enduranceevent, when blood glucose and muscle glycogen are significant soucres of energy
133
Q

Explain the kind of athletes that may need additional protein in their diet -

A
  • Athletes who are trying to build or repair tissue by exercise training
  • Moderately trained endurance athletes can increase 1-1.2
  • Heavy resistance training 1.6
134
Q

How are the protein needs of an individual determined? -

A
  • by doing a nitrogen balance study
  • a nitrogen balance study living in a whole room calorimeter and the nitrogen intake and content of wastes are measured under well controlled conditions
135
Q

During a nitrogen balance study, where is the nitrogen excreted from the body coming from? -

A

urine, feces, and sweat

136
Q

Know the differences between nitrogen balance, negative nitogen balance and positive nitrogen balance -

A

Nitrogen balance: nitrogen in = nitrogen out

Negative nitrogen balance: nitrogen in < nitrogen out

Positive nitrogen balance: nitrogen in > nitrogen out

137
Q

What are the protein consumption recommendations for athletes in training? -

A

1.2 g/kg/day during the 1st few weeks

138
Q

Describe the pregame meal. what is the purpose of the pregame meal? -

A
  • 4 hours prior to exercise. Should be high carbs (3-5 g/kg) and only have enough protein and fats to minimize hunger urges
  • helps to assure muscle and liver glycogen stores are filled to capacity but not to give gastric distress during exercise
139
Q

In what muscle does CHO-loading increased stored glycogen? Explain why both are necessary -

A

if exercise isn’t included then it will result in weight gains because the glycogen will not be used

140
Q

How does CHO-loading improve aerobic performance? -

A
  • It’s like filling a tank of gas, greater stores of muscle glycogen increase endurance time
  • increase the duration of race pace and delays onset of fatigue. Allows racer to maintain optimal race pace for longer period of time
141
Q

Does CHO loading increase race pace? Explain your answer -

A

No b/c the lactate threshold isn’t affected by the amount of glycogen in the muscle

142
Q

Describe the 3 methods of CHO-loading -

A

Classic:
7 days total
hard to tolerate depletion and low -> high carb diets
3 days low carbs and strenuous exercise (intentional depletion of muscle glycogen)
3 days 90% of caloric intake regular exercise
last day is day of the race
training tapered -> CHO intake increases

Modified Classic:
7 days training volume tapered 5 days
6th day rest, 7th competition (time frame can be adjusted)
3 days 50% carbohydrates of caloric intake
3 days 70% carbohydrates of caloric intake
easier to adhere to

One-day method:
consume 10g of carbohydrates per kg of bodyweight day before exercise
has same effect as classic methods

143
Q

When should a person consider CHO-loading? -

A
  • Continuous competitive endurance events lasting longer than 90 minutes
  • Not for regular training, games or most sporting events that last longer than 90 minutes
  • When they are going to exercise regularly, train, or compete in endurance events
144
Q

Why is it not necessary for a person to CHO-load prior to every training session that lasts longer than 90 minutes? -

A
  • b/c if you follow the following practices it’s usually sifficient to meet nutritional needs of training program:
  • Consume a high carbohydrate diet sufficient in calories
  • Good pre-game meal 3-4 hours prior
  • consume carbs during exercise
  • and intensity of training is not as intense as competition, hydration is usually more available
145
Q

What are the hydration guidelines during the several hours preceeding exercise? -

A
  • 5-7 ml/kg of BW 4 hours before exercise. If urine is still dark 2 hours later an additional 3-5 ml can be taken in
146
Q

What is a personal hydration plan? -

A

b/c everyone is different and intensity and duration of exercises are different as well, there is a difference b/t sweet compositions and rates b/t individuals thus a plan needs to be created to replenish lost fluids during exercise

  • replenishes lost water due to sweat to maintain body weight within- 2% of pre exercise body weight
  • Provides adequate amounts of CHO to maintain blood glucose and as an exogenous source of carbs to the exercising muscle replenishes lost electrolytes
147
Q

Write the equation used to calulate the volume of fluid that should be consumed during exercise -

A

Sweat Rate = Pre exercise (kg) - post exercise (kg) + fluid intake (L)

148
Q

How does duration of exercise change the recommendations for CHO consumption during exercise? -

A
  • Exercise < 60 min < 30 g/hour CHO
  • Exercise > 60 min > 30 g/hour CHO
  • Exercise > 2 hours > 60 g/hour CHO
  • Exercise > 2.5 hours > 90 g/hour CHO
  • Drink should be 4-8% CHO
149
Q

A food label of a sports drink indicates that one serving (240 ml) has 14 grams of CHO. What is the CHO concentration of this sports drinks? -

A

240 ml = 1 dl / 100 ml = 2.4 dL

14 g / 2.4 dL = 5.83%

150
Q

John wants to consume 60 g of CHO per hour during his bike rides. If his sports drink has 15 grams of CHO per serving (240 ml), what is the volume of sports drink that he needs to consume per hour? -

A

15g x 4 = 60g

240ml x 4 = 960 mL/hr

151
Q

Karen determines from her training logs that the volume of fluid that she should be consuming during exercise is 1.25 L/hr. If she consumes a 6% sports drink, how many grams of CHO will she be consuming per hour? -

A

6% = 6g/dL

  1. 25 L / .1 = 12.5 dL
  2. 5 dL x 6 = 75g CHO/hr
152
Q

When is it appropriate to consume CHO during exercise? -

A

early in exercise and continue every 10-20 min. throughout exercise session

153
Q

When is it necessary to consume CHO during exercise?

A

Exercise more than 60 min.

154
Q

Bill’s exercise program includes a 45-60 min. jog, 4 days per week. His training journal indicates that his typical pre-exercise body mass is 78.5 kg. He doesn’t drink fluids while jogging b/c he doesn’t like to carry water bottles. Would you recommend that he consume fluids during his typical exercise sessions? explain. -

A

loss of 2% or greater body weight during exercise leads to dehydration

155
Q

Describe the fluid consumption guidlines for different durations of exercise -

A

16-24 fl oz per pound lost during exercise

156
Q

How does a carbohydrate mouth wash help in maintaining performance? -

A

CNS response, receptors in the oral cavity provide afferent signals to the higher brain centers to modify output/motivation

157
Q

When would you recommend a CHO mouthwash during exercises? -

A

High intensity exercise durations of less than 60 min.

158
Q

John weighs himself after a 60 minute jog and finds that he lost 2 pounds even though he drank 1 Liter of water during his jog. How much fluid should he drink now that he is done exercising? -

A
  1. 12 lb = 1 kg
  2. 12 x 2 = 4.24 kg lost
  3. 24 kg + 1.0 L = 5.25 L/hr
159
Q

Describe the after-exercise CHO consumption recommendations when replenishment of muscle glycogen is important -

A

within 1st 30 min consume 1- 1.5 g CHO per kg BW

repeat every 2 hrs for 4-6 hrs

160
Q

What type of beverage can be consumed following exercise? -

A
  • Fluid replacement drinks (4-8% carb-electrolyte mix) should contain sucrose, glucose and glucose polymers
  • also contain potassium, sodium, and chloride
  • carb replacement drinks 4-8% carb mix. also carb protein ratio of 3-4:1
161
Q

What are the differences b/t a sports drink consumed during exercise and a recovery drink consumed following exercise? -

A
  • sports drinks w/ higher carbs (> 4-8%) can replace muscle glycogen and contain protein.
  • 3-4:1 carb-protein ratio stimulates glycogenesis in muscle
  • Recovery drinks usually have more proteins and carbs than recommended
162
Q

Why is chocolate milk promoted as a recovery drink? -

A
  • 90% water for rehydration
  • Vitamin and Minerals
  • Whey and Casein Proteins
  • 3-4:1 CHO to ratio protein
  • enhances glycogen stores, absorption and retention of water, repair of muscle tissue

Exercise Physiology (2 decks)

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