Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Principles of Physiology > Exercise Physiology > Flashcards

Exercise Physiology Flashcards

1
Q

Quantifying performance in terms of power

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Muscle fiber types

A

Slow twitch, fast twitch a and b

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Slow-twitch muscle fibers

A
  • Fatigue-resistant, for endurance (e.g. keeping your head elevated)
  • Least powerful
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Fast-twitch a fibers

A
  • Intermediate power
  • Fast fatigue-resistant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Fast twitch b fibers

A
  • Most powerful (e.g. for sprints)
  • Fast fatigable
  • Twice as powerful as slow-twitch
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Table showing classification of muscle fiber types

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Force is equivalent to ___

A

Number of cross-bridges per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Diameter of muscle fibers

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which fibers have the largest diameter and why?

A
  • Fast twitch a
  • It’s packing more things into one fiber (more cross-bridges and more mitochondria for aerobic fibers)
  • Taking up space is a resource
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Fast twitch b fibers are large but ___

A

Don’t have much oxidative capacity (mitochondrial and capillary densities are low, more space for actin and myosin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Slow twitch fibers have a very ___ glycolytic capacity

A
  • Low
  • It only produces ATP at a certain level, so it can’t have too many cross-bridges
  • If it has too many cross-bridges, it would use up ATP too quickly
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Glycogen stores in fast-twitch fibers

A
  • Very high
  • Because glycolysis is featured
  • A lot of ATP is produced
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why does it not make sense to store so much glycogen in slow-twitch fibers?

A
  • The rate at which you can go through glycolysis and feed mitochondria is limited by the sluggishness of the aerobic pathways of the mitochondria
  • So no reason to have a lot of glycolytic enzymes, would just cause a buildup of pyruvate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Stained muscle fibers

A
  • Every cell has myosin, but only slow-twitch are dark because of the pH in the lab
  • Fast twitch a are the largest
  • The same muscle has a mixture of fiber types
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Distribution of fiber types (within the same individual)

A
  • Great variability between individuals
  • Mostly determined genetically
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Energy systems (source of ATP for cross-bridge formation)

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the three energy systems that act as sources of ATP for cross-bridge formation?

A
  • Phosphogen system
  • Glycolytic system
  • Oxidative (aerobic)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Phosphogen system

A

10 seconds
- Stored ATP- 3 secs
- Phosphocreatine - 7 secs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Glycolytic system

A

1-2 minutes, primarily described fast twitch b muscle fibers
- Glycolysis
- Inefficient (not getting a lot of ATP) but fast
- Buildup of lactic acid- must be buffered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which type of muscle fiber is the glycolytic system associated with and why?

A
  • Fast twitch b
  • They have a lot of glycolytic enzymes in the cytosol
  • A lot of carbohydrates to feed into glycolysis
  • Not a lot of mitochondria to get in the way or capillaries to take up space
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Downside of aerobic pathway for energy

A
  • Stored ATP (phosphogen system) and glycolysis (glycolytic) enable more cross-bridge formation per minute than aerobic
  • If you want to maintain cross-bridges using aerobic pathways, a smaller number will be able to be maintained
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Capacity of energy systems vs. exercise duration

A
  • Stored energy/phosphocreatine on green line gone quickly (but readily available)
  • Glycolysis starts off low and when it turns on (takes a little time) but then spikes, stays there for minutes, then depletes
  • For long-term aerobic pathways, it takes minutes for them to get up to full capacity, but can be maintained for hours/days
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How do cells know to increase glycolytic pathway activity?

A
  • All happens within the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Fiber type recruitment order

A

As the requirement for more power from muscle contraction increases the recruitment order is as follows:
- Slow-twitch (aerobic): FIRST
- Fast-twitch a (aerobic/anaerobic): SECOND
- Fast-twitch b (anaerobic): LAST

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Anaerobic threshold (the old story)

A

As exercise intensity increases:
- Oxygen levels are insufficient to support aerobic pathways
- Pyruvate, the product of glycolysis, accumulates in cytosol
- At a higher cytosolic concentration of pyruvate the anaerobic enzyme pyruvate dehydrogenase now acts on substrate to increase anaerobic metabolism
- Lactate accumulates as “waste product” and enters blood
- Buffering of lactate by HCO3- results in increased VCO2
- VE increases disproportionately to VO2 due to ↓pH and ↑VCO2

  • Many subsequent studies do not support this hypothesis.
  • Lactate is not just a “waste product” but a resource that is shuttled between cells to be used as fuel, be converted into glucose (in liver) and serve as a signaling molecule (autocrine, paracrine, endocrine)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Comprehensive flowchart of metabolism

A
  • Glycogen or glucose is used in glycolysis to create pyruvate and a little bit of ATP
  • Pyruvate enters the Krebs cycle, producing more ATP (slow)

Sources of energy for aerobic pathways:
- Glucose and glycogen
- Free fatty acids (fat is the primary fuel source of the body)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Can fatty acids be used in the glycolytic pathway?

A

No, they are purely aerobic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Burning of what nutrient yields the slowest ATP production rate?

A
  • Burning fat aerobically
  • Burning fatty acids to produce ATP is a slower burn than using glycolysis as a source -> oxidative phosphorylation
29
Q

How can you pick up your ATP rate of delivery but still stay aerobic?

A
  • Use glycose and glycogen, fed through the aerobic pathways (a bit faster than fat metabolism)
  • Slow-twitch muscle fibers will use fat as their primary fuel source when they’re not using a lot of energy. If they need to produce more power, they will shift to burning glucose/glycogen
30
Q

What pathway do fast-twitch fibers lean more heavily upon than slow-twitch?

A
  • Glycoslysis to produce ATP quickly
  • Instead of pushing all the pyruvate down aerobic pathways, it goes down anaerobic pathways, producing lactic acid
31
Q

End-product inhibition with lactate

A
  • It slows down the enzyme that starts the pathway of pyruvate - acetyl CoA (end-product inhibition)
  • This limits ATP production
32
Q

How do carbohydrates being burned during exercise affect fat storage after?

A

Using carbohydrates during exercise results in less fat being stored after because glucose can be very easily formed into fat in fat cells (less glucose there to be converted into fat)

33
Q

Phosphocreatine and ATP

A
  • When ATP levels drop (as a result of contraction), phosphocreatine produces more ATP to replenish it
  • ATP inhibits the breakdown of phosphocreatine
34
Q

How does ATP affect aerobic pathways?

A
  • When cross-bridges consume ATP, ATP levels drop
  • ATP inhibits glycolytic enzymes in the glycolysis pathway
  • If you disinhibit those enzymes (with decreased ATP levels), glycolytic pathways pick up (this takes a few seconds)
35
Q

How would the flow-chart look different depending on the type of muscle fiber?

A
  • If the muscle were slow-twitch, there would be a big emphasis on oxidative phosphorylation and less on glycolysis
  • If it were fast-twitch b, glycolysis would be emphasized and oxidative phosphorylation would be a smaller box
36
Q

Anaerobic threshold

A
  • The x-axis shows oxygen consumption going up (proportion to power of muscles)
  • As your VO2 goes up, there is an impact on blood lactate, arterial PCO2, and ventilation
  • CO2 goes down as a respiratory compensation for metabolic acidosis (makes
    pH more acidic)
    -CO2 from anaerobic pathways and from buffering lactate
37
Q

Problems with anoxia triggering lactate increase in blood

A
  • PO2 does not drop to 2 mmHg which is theoretical limit at which aerobic pathways experience oxygen deficit
  • Lactate is used to shuttle important molecules into and out of muscle cells
  • Lactate is removed from the blood and “consumed” by other cells
  • Trained athletes demonstrate a transient increase in lactate at their AT that diminishes over time

*N.B. at very intense levels of exercise, above AT, anoxia still plays a role
*N.B. Lactate Threshold is still an important measure for athletic training

38
Q

Graph showing what happens to lactate when you exercise

A

Lactate levels go up within the first ~20 minutes, then as you continue, it comes back down (body adapts, maybe liver metabolizes it more quickly)

39
Q

Percentage of CHO and Fat vs. Exercise Intensity

A
  • You start with slow-twitch, and as the intensity of exercise increases, you recruit fast-twitch fibers
  • The graph demonstrates the percentatge of calories derived from burning fat and carbohydrates
  • The Y-axis is the PERCENTAGE of energy derived from fat vs. carbohydrates
  • Overall, as intensity of exercise increases, the total total number of calories being burned goes up, but the % derived from fat drops and the % derived from carbs goes up (you still burn fats0

Why? (figure shows)
- Slow-twitch fibers switch from fat to carbs to generate more power
- Recruitment of fast-twitch fibers which use glycolysis exclusively

40
Q

Glycogen depletion graph

A
  • Shows how quickly you use up glycogen stores when the intensity of exercise increases
  • At 31% of VOmax, you can go 180 mins and you’ve only depleted glycogen by ~50%
  • If you’re above your VOmax, you’ll deplete your muscles of glycogen within minutes
41
Q

Respiratory changes with increased exercise intensity

A
  • You might extract more oxygen from the air you’re breathing in
  • You’re certainly moving more air in and out of your lungs
  • Minute ventilation goes up (consuming more oxygen)
42
Q

What is VO max?

A
  • Level of exercise where you’re consuming the maximum level of oxygen
  • However, this is not 100% of your power output
43
Q

Why is VOmax not maximum power output?

A
  • At VOmax, you might still have some fast-twitch b muscle fibers in reserve
  • You can generate more power than your VOmax power
44
Q

Graph showing glycogen restoration with diet

A
  • If you’re exercising at your VOmax for an extended period of time, consuming glucose is helpful (carboloading)
  • The graph shows recovery of glycogen with different types of diet
  • A person who only eats fat and protein has not replenished their glycogen even after 5 days
  • Some people can lean on metabolizing fats more than carbs but it takes time to get to this point
45
Q

Oxygen and myoglobin

A
  • Myoglobin only binds one oxygen molecule (hemoglobin binds 4)
  • Has a higher binding affinity for oxygen than hemoglobin does
  • So when the partial pressure of oxygen drops from 100 to 40 mmHg, oxygen unbinds from hemoglobin (75% saturated)
  • But at a PO2 of 40, it’s a bit lower that inside the muscle cell, and myoglobin is saturated with oxygen
  • However, when the muscle becomes active, ATP levels drop, aerobic enzymes feeding glycolysis are disinhibited, more pyruvate goes through the Krebs cycle and electron transport chain
  • Oxygen levels drop as it is consumed at a fast rate
  • The first thing to respond is myoglobin
  • As the PO2 drops below 40 mmHg as metabolism increases, the first thing that happens is that oxygen can be released from myoglobin to keep the aerobic pathways fed with oxygen
  • It might take the cardiovascular and respiratory systems time to catch up and deliver oxygen
  • In this way, myoglobin is a buffer
46
Q

Fuel- glucose

A
  • From blood (liver makes it from glycogen
  • Stored in muscle (glycogen)
  • Fast delivery rate
47
Q

Fuel- fat

A
  • Very abundant energy source
  • Slow delivery rate
48
Q

Fuel- protein

A
  • Abundant but not ideal source
  • Slow delivery rate
49
Q

Graph of O2 consumption as a function of exercise time at a given level of effort

A

16:00

50
Q

EPOC (excess post-exercise oxygen consumption)

A
  • Increase in oxygen cosumption per minute that extends after an exercise
  • The more intense and the longer the duration of the exercise, the larger the EPOC
  • There are two phases: rapid component (mostly restocking component) and prolonged component (lasts 12 hours)
51
Q

EPOC rapid component

A
  • Restock Hb and myoglobin with O2
  • Restore ATP and phosophocreatine
  • Increased body temp
  • Lactate removal
52
Q

EPOC prolonged component (less is known)

A
  • Shift from carb to fat metabolism?
  • Increased protein synthesis?
  • Micro-damage and inflammation in muscle that stimulate synthesis of new parts of muscle
53
Q

What causes fatigue?

A
  • Energy depletion
  • Buildup of metabolic byproducts
  • Nervous system
54
Q

Energy depletion (cause of fatigue)

A
  • Phosphocreatine (short, hard efforts)
  • Glycogen depletion (longer efforts)
55
Q

Buildup of metabolic byproducts (cause of fatigue)

A
  • Lactic acid (current research does not support this as having a direct effect on weakening muscle contraction)
  • Electrolyte changes (intracellular or extracellular):
    -Increase in extracellular K+?
    -Depolarization of Vm of muscle cells
    -Less release of Ca++ from sarcoplasmic reticulum
56
Q

Nervous system (cause of fatigue)

A
  • Physiological (sensory neuron activity in muscle depolarizes motor neurons in spinal cord)
  • Psychological (discomfort does not discourage)
57
Q

What changes does endurance training lead to?

A
  • Increased vascularization - more capillaries
  • Increased myoglobin
  • More mitochondria
  • More oxidative enzymes
  • Improved fat metabolism
58
Q

Anaerobic training (increase anaerobic threshold and increase anaerobic capacity)

A
  • More glycolytic enzymes
  • More glycogen stored
  • Increased capacity to utilize lactate:
    -Less release from active muscle at a given power
    -More uptake by other cells - lactate shuttling (e.g. some muscle metabolizes lactate; liver makes glucose from lactate)
  • Psychological training: deal with pain
59
Q

Graph showing time in weeks vs. control

A

28:00

60
Q

What causes muscle cramps?

A
  • Overuse, muscle strain, holding the same position (prolonged contraction)
  • K+, Mg++, or Ca++ deficiency
  • Dehydration
  • Symptoms of underlying conditions (nerve compression, inadequate blood supply)
  • There are many theories but in most cases, the cause of muscle cramps is unknown
61
Q

Recent theory about muscle cramps

A
  • A recent theory implicates sensory nerve endings in muscle that are excited when muscle is fatigued or overused, resulting in a spinal cord reflex that activates motor neurons going to the same muscle
  • In experimental animals, blocking the sensory axons coming out of a muscle or motor axons going into a muscle decreases cramping significantly
62
Q

Diameter of muscle fibers

A

ST: small
FTa: largest
FTb: large

63
Q

Mitochondrial density in muscle fibers

A

ST: high
FTa: high
FTb: low

64
Q

Capillary density in muscle fibers

A

ST: High
FTa: Medium
FTb: Low

65
Q

Myoglobin content in muscle fibers

A

ST: High
FTa: Medium
FTb: Low

66
Q

Metabolic aspects?

A
67
Q

At low levels of exercise, most ATP is generated from metabolizing fats. At high levels of exercise, most ATP is generated from metabolizing carbohydrates. List and briefly explain two reasons why there is an overall shift from burning fats to burning carbs when exercise level goes from low to high.

A

1) Higher level of exercise requires a higher delivery rate of ATP. Aerobic pathways shift from fat to carbohydrate metabolism when a greater rate of ATP delivery is required.
2) Higher level of exercise requires recruitment of more fast-twitch muscle fibers that metabolize carbohydrates more than fat.

68
Q

In a muscle cell, a drop in the concentration of ATP will cause a (3 changes)

A
  • decrease in glycogen synthesis
  • increase in the production of CO2
  • increase in the breakdown of phosphocreatine

A Principles of Physiology (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions