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Exercise Physiology > Aerobic Energy Systems > Flashcards

Aerobic Energy Systems Flashcards

1
Q

What is the function of Hexokinase?

A
  • Slow Glycolysis

- converts glucose to glucose-6-phosphate in the cell so it can be stored as glycogen

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2
Q

What is the function of Insulin?

A
  • Allows transport of glucose into the cells
  • decreased activity during exercise
  • stimulates glucose uptake into the tissues and glycogen storage
  • stimulates fat cells to form fats from fatty acids and glycerol
  • inhibits the liver/kidneys from making glucose from intermediate compounds of metabolic pathways
  • stores nutrients right after a meal by reducing the concentration of glucose, fatty acids, and AA in the blood strew,
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3
Q

What is the function of phosphorylase?

A
  • Fast and Slow Glycolysis

- assists with breakdown of glycogen

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4
Q

What is the function of Epinephrine?

A
  • Increases Heart Rate
  • Stimulates Phosphorylase, Hormone Sensitive Lipase
  • activates glut 4
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5
Q

What is the function of FAD?

A

-hydrogen carrier from the Krebs cycle to the ETC

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6
Q

What is the function of Isocitrate Dehydrogenase? (IDH)

A

-rate controlling enzyme of the Krebs Cycle

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7
Q

What is the function of Phosphofructokinase?

A
  • enzyms that assists glycolysis
  • stimulated by increased cell concentration of ADP and AMP
  • inhibited by ATP and decreased pH
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8
Q

What is the function of PDH?

A

-transforms Pyruvate to Acetyl CoA by removing carbon so it can be used in the Krebs Cycle

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9
Q

What is the function of Lactate dehydrogenase muscle form?

A
  • Fast Glycolysis - anaerobic

- recycles NAD in fast glycolysis and converts pyruvate to lactate

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10
Q

What is the function of lactate dehydrogenase heart form?

A
  • aerobic - slow glycolysis

- converts lactate to pyruvate

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11
Q

What is the function of NAD?

A

-carries electrons and hyrdrogens to the Krebs cycle/ETC

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12
Q

What is the function of ATP synthase?

A

ADP and Pi are joined together by ATP synthase to create ATP in the ETC

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13
Q

What is the function of succinate dehydrogenase? (SDH)

A
  • Aerobic enzyme used during the Krebs Cycle

- removes hydrogen from succinate

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14
Q

What is the function of Cytochrome oxidase?

A

-accepts electrons from cytochrome c to be converted to water in the ETC

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15
Q

What is the function of norepinephrine?

A

-increases blood pressure and heart rate when the body is put under stress

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16
Q

What is the function of hormone sensitive lipase?

A

-breaks down fasts for utilization as fuel

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17
Q

What is the function of cytochrome c?

A

-transports one electron at a time in the ETC

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18
Q

What is the function of NADH Dehydrogenase?

A

-Removes H from NADHH and movie it to the inter membrane space of the ETC

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19
Q

What is the function of Ubiquinone?

A

-electron carrier in the electron transport chain

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20
Q

What is the function of Acetyl CoA

A

delivers carbons to the krebs cycle from glycolysis

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21
Q

What is the function of oxaloacetate

A

combines with acetyl CoA to create a 6 carbon chain to be used in the krebs cycle to create energy

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22
Q

What precautions should a diabetic take before exercising? Explain why these precautions are necessary.

A
  • During exercise insulin decreases so glucose enters the cell through glut4 activation by calcium
  • glut4 is activated by muscle contraction (Calcium and epinephrine)
  • This increases glucose uptake into the cell which decreases blood glucose levels
  • Could result in hypoglycemia
  • Diabetics should check blood glucose levels before exercise and make sure insulin levels are not high prior to exercise
  • high insulin and exercise = crash
  • low blood glucose and exercise = crash
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23
Q

Explain why refueling after hard or long workouts should be started within 30 minutes to 2 hours after the workout

A
  • After exercise insulin is low, Glut4 remains active, and glycogen synthase activity increases due to low muscle glycogen levels
  • Eating a 4:1 CHO:PR meal will restore muscle glycogen levels the most efficiently
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24
Q

How is energy production via aerobic pathways limited by VO2?

A
  • ability of the heart and blood vessels to transport oxygen to the active muscle tissues
  • Cardiac output and redistribution of blood flow to active tissues (CO=SV x HR hence a person with a larger SV will have an advantage)
  • Ability of muscle cell to take up and use oxygen (mitochondrial enzyme development)
  • all are trainable to some degree
  • Heart disease and respiratory disease have a negative impact on VO2
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25
Q

What is the function of Glycolysis?

A

Fast: provide ATP rapidly via partial breakdown of glucose and glycogen

  • use when ATP resynthesis via O2 system is inadequate to meet the rate of ATP demand
  • to extend ATP resynthesis beyond the ATP PCr system

Slow: provides substrates/reactant for the Krebs Cycle and ETC while providing a small amount of energy

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26
Q

What is the function of the Krebs Cycle?

A 
-produces NADH and FADH for use in the electron transport chain while releasing some ATP
For every glucose:
-2 ATP
-10 NADH
-2 FADH
27
Q

What is the function of the electron transport chain?

A

-the create of ATP via hydrogen/electron gradient

28
Q

What is the function of Beta Oxidation?

A

-to cleave 2 carbon from free fatty acid and continues until you are left with 2 pairs

29
Q

How many ATPs are produced from each NADH+H in the ETC?

A

-cost of each= appx 0.5 ATP

3 ATPs from NADHH - 0.5 = 2.5ATPs

30
Q

How many ATPs are produced from each FADHH in the ETC?

A

-cost=appx 0/5 ATP

2 ATPs from FADHH - 0.5 = 1.5 ATPs

31
Q

What is the function of H in the electron transport chain?

A

increases gradient in the inter membrane space which allows for the flow of electrons

32
Q

What is the function of electrons in the ETC

A

transfer of electrons provide energy for H pumping by creating a gradient

33
Q

What is the function of oxygen in the ETC?

A

Final electron receptor forming H2O`

34
Q

Define Oxidative Phosphorylation

A
  • The process of producing energy via the ETC

- Oxidation process producing ATP

35
Q

After free fatty acids are broken down to Acetyl-CoA in beta-oxidation, what happens to the Acetyl-CoA

A

it enters the Krebs cycle

36
Q

Which is more effective for the clearance of lactate, active recovery or passive recovery? Why?

A
  • Active Recovery
  • It allows blood to keep moving to clear lactate
  • Clearance mechanisms
  • Lactate Shuttle: Muscle cell to muscle cell in same muscle, lactate consumed in mitochondria
  • Muscle cell to blood: from muscle to heart, liver, or other muscles, heart consumes lactate
37
Q

Given similar lactate thresholds, why do athletes with high VO2 max values perform better in endurance events than those with low values?

A
  • lactate is expressed as a percentage of VO2 max

- the person with a higher VO2 max will be able to exercise at higher steady state than the person with a lower VO2 max

38
Q

Given similar VO2 max values, why do individuals with higher lactate thresholds perform better in endurance activities than those with lower values?

A
  • lactate thresholds are expressed as a percentage of VO2max

- those with higher lactate threshold are able to exercise longer before fatigue

39
Q

What factors determine lactate threshold?

A
  • mitochondrial mass/capillary density
  • LDH
  • muscle fiber makeup

-can train factors to shift lactate threshold to the right

40
Q

Explain 2 reasons why lactate begins to rise rapidly at lactate threshold?

A
  • ATP demand is greater than what can be made
  • recruit more type II muscle fibers
  • lactate production exceeds clearance
41
Q

What are the two primary determinants of VO2max? Explain how training enhances the function of each.

A
  • Cardiac output: SV increases, HR decreases, CO increases which allows body to work less to transport oxygen throughout body
  • A-VO2 Difference: Mitochondrial Function: the greater the difference the more oxygen you are able to take up
42
Q

During the initial stage of aerobic exercise, before reaching steady state, we contract and oxygen deficit.

Where do we gain the energy needed to sustain exercise during this period?

A

energy for exercise is met by the smooth blending and overlap of the body’s three energy systems

43
Q

During the initial stage of aerobic exercise, before reaching steady state, we contract an oxygen deficit.

Explain oxygen deficit. What are the implications for performance?

A
  • oxygen needs that are met anaerobically instead of aerobically
  • training to decrease the time of the O2 deficit will increase cardiac output, increase mitochondrial mass, increase oxygen transport, increase VO2 max, and increase capillary density
44
Q

Explain how lactate threshold training may be beneficial for people recovering from a myocardial infarction, cancer, or even a sedentary person

A
  • if able to work more aerobically, more oxygen will be in the blood and the heart will work less
  • increases function capacity to do daily work/activities
45
Q

Margaret and Nicole are endurance athletes of the same age and training background. Maggie weighs 58 kg and her VO2max is 3.2 L/min. She can sustain exercise at about 82% of her VO2max. Nicole weighs 59 kg and her VO2 max is 3.2 L/min. She can sustain exercise at about 65% of her VO2 max.

Based on the info provided, would you expect Maggie or Nicole to perform better in an endurance event lasting 45 min or longer?

A
  • they have the same VO2max so a difference in endurance activity would be determined by lactate threshold
  • Maggie has a lactate threshold of 82% of her VO2max and Nicole has a lactate threshold of 65% of her VO2max.
  • Maggie can run at a faster speed than Nicole and remain at steady state
  • Maggie is likely to perform better in an endurance event lasting over 45 min or longer
46
Q

Explain the effect of intensity of exercise on fuel selection utilization.

A
  • High intensity short term: PCr to produce ATP fast
  • Muscle glycogen used during longer intensity activities both aerobically and anaerobically
  • fatty acids used during longer intensity to produce a lot of ATP
  • Fuel sources are recruited based on the rate of need of ATP
47
Q

Explain why several days of high (70%) carbohydrate may be beneficial for an endurance activity

A
  • muscle and liver glycogen depletion during exercise

- Can double muscle glycogen stores by carboloading which will increase endurance

48
Q

Explain mobilization of fatty acids

A
  • Mobilization from fat cells
  • have to break acid chains off of glycerol (hormone driven)
  • epinephrine and norepinephrine decrease insulin which activate hormone sensitive lipase (HSL breaks off first fatty acid)
  • Diglyceride Lipase, Monoglyceride lipase act on 2nd and 3rd Fas
  • FAs bind to PR carrier albumin to be transported to muscle
49
Q

Explain uptake of fatty acids

A
  • uptake into muscles in concentration dependent
  • FFAs released from albumin in cytosol
  • once in cell must be activated by Acetyl CoA using 2 ATPs each
50
Q

Explain translocation of Fatty Acids

A
  • Translocation into mitochondria
  • FFAs diffuse into mitochondria using CPT1 and CPT2 (carnatine translocase)
  • Aerobic training increases mitochondrial mass and CPT therefore increases FFA oxidation
51
Q

Explain Beta Oxidation of fatty acids

A
  • Beta Oxidation: breakdown of FFA to Acetyl CoA, NADH, FADH
  • Purpose: to cleave 2 carbon units off of FFA chain to be converted to Acetyl CoA
  • For every time through bOx you get 1 NADH and 1 FADH for the ETC
52
Q

Explain oxidation of fatty acids

A

-Oxidation of AcetylCoA in Krebs and ETC

53
Q

The body has ample fat stores, so what is the importance of adequate carbohydrate stores for endurance performance? Why can’t the endurance athlete just depend on fat metabolism?

A
  • Fat burning does not occur until at least 45 minutes of moderate intense exercise
  • Carbohydrate (Muscle Glycogen stores) must be used until this point
  • the use of fat burning for fuel must be trained
54
Q

What is the effect of exercise on post-exercise metabolic rate (EPOC) and why is an elevated metabolic rate beneficial?

A
  • EPOC: Excess Post Exercise Oxygen Consumption
  • EPOC increased with increased intensity and duration
  • Increased caloric cost of exercise—weight loss or control
  • Exercise 5xs a week for 40-60 min for weight loss —200-300 min of exercise per week is optimal
55
Q

Under what conditions is protein metabolism (breakdown) increased?

A

when CHO stores are low

56
Q

Discuss protein needs for endurance trained people

A
  • For endurance athletes activities lasting longer than 90mins, small amount of PR is used as fuel
  • Replace AAs used for energy and repair post exercise
  • 1.2-1.4 g/kg BW/day
57
Q

Discuss protein needs for power trained people

A
  • Strength athletes need more to repair muscle and increase mass
  • 1.4-1.8 g/kg BW/day
58
Q

What is meant when we say that aerobic metabolism is glycogen sparing (especially fat burning)?

A
  • same amount of fuel used differently

- more aerobic/fat burning spares the glycogen to be used later

59
Q

From a performance perspective, why are low carbohydrate diets a poor idea?

A
  • carbohydrates provide muscles with glycogen stores that provide fuel for activity
  • low carbohydrates would result in low glycogen stores and a reduced time to fatigue
60
Q

What are the probable causes of fatigue during endurance activities lasting 14-30 min and lasting 90 min to 3 hours?

A

14-30: decreased pH inhibits hemoglobin
90-3h: muscle glycogen depletion: decreased oxaloacetate slows krebs cycle
-liver glycogen depletion: source of glucose for blood, decrease causes CNS fatigue
-Dehydration: increased blood viscosity, decreased oxygen transport, increased body temperature

61
Q

What physiological adaptations occur as a result of training for fat metabolism?

A
  • increased sensitivity of hormone sensitive lipase
  • greater number (mass) of mitochondria
  • Increased CPT1 and CPT2
  • Increased Beta Oxidation enzymes
62
Q

What physiological adaptations occur as a result of training for lactate threshold?

A
  • LDH converts lactate to pyruvate to go into the Krebs cycle
  • increased mitochondrial mass
  • increased capillary density
  • increased Krebs/ETC enzymes
  • increased A-VO2 difference
63
Q

What physiological adaptations occur as a result of training for VO2 max?

A
  • possible increase in cardiac output based on increased stroke volume
  • increased mitochondrial mass
  • increased capillary density
  • increased myoglobin
  • increase in Krebs and ETC enzymes
  • Improved A-VO2 difference
64
Q

What type of exercise is most beneficial for weight loss? Exercise at a low HR for 45min to ensure a greater percentage of fat burning, resistance training to increase muscle because it increases metabolic rate, or high intensity exercise?

A
  • EX at low HR is not effective unless done for a very long time (moderate intensity more effective 70-75%)
  • Resistance: muscle is always metabolically active and increase muscle mass also increases amount of food intake

Exercise Physiology (2 decks)

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