Lecture 6

Question 1

What is the definition of fatigue?

Answer 1

• Decrements in muscular performance with continues effort, accompanied by sensations of tiredness
  -Inability to maintain the required power output to continue muscular work at a given intensity

Question 2

What are the 4 major causes of fatigue?

Answer 2

1. Inadequate energy delivery/metabolism
2. Accumulation of metabolic by-products
3. Failure of muscle contractile mechanism
4. Altered neural control of muscle contraction

Question 3

What is PCr used for?

Answer 3

Short-term, high-intensity effort

Question 4

What happens to glycogen reserves during fatigue?

Answer 4

They are limited and get depleted quickly with high intensity and in the first few minutes of exercise

Question 5

What happens to the fibers that are first recruited?

Answer 5

They often get depleted faster

Question 6

In what order do fibers get recruited?

Answer 6

Type 1 fibres (light/moderate intensity)
Type 2a fibres (moderate/high intensity)
Type 2x fibres (maximal intensity)

Question 7

What happens when muscle glycogen decreases?

Answer 7

Liver glycogenolysis increases

Question 8

What does muscle glycogen depletion + hypoglycemia equal?

Answer 8

Fatigue

Question 9

What happens when there is no glycogen in muscle glycogenolysis?

Answer 9

Inhibition substrate oxidation

Question 10

What are the metabolic by-products of fatigue?

Answer 10

Pi (rapid breakdown of PCr, ATP)
Heat (retained by body, core temperature increases)
Lactic acid (product of anaerobic glycolysis)

Question 11

What temperature causes exhaustion to be the longest?

Answer 11

11 degrees

Question 12

What temperature causes exhaustion to be the shortest?

Answer 12

31 degrees

Question 13

What happens when H+ accumulates?

Answer 13

It causes decrease of muscle pH

Question 14

Possible causes of failure of neural junction?

Answer 14

-Reduced ACh synthesis and release
-Altered Ach breakdown in synapse
-Increase in muscle fiber stimulus threshold
-Altered muscle resting membrane potential

Question 15

Does the central nervous system play a role in fatigue?

Answer 15

Yes, but I do not fully understand yet

Question 16

What does muscle soreness result from?

Answer 16

Exhaustive or high-intensity exercise, especially performed for the first time

Question 17

When can acute muscle soreness be felt?

Answer 17

During or immediately following strenuous or novel exercise

Question 18

What is Edema?

Answer 18

Acute muscle swelling

Question 19

What does DOMS stand for?

Answer 19

Delayed-onset muscle soreness

Question 20

What is the major cause of DOMS?

Answer 20

Eccentric contraction

Question 21

What is indicated as structural damage?

Answer 21

Muscle enzymes in the blood

Question 22

What kind of sarcomeres are anchoring points of contact for contractile proteins?

Answer 22

Z-disks

Question 23

What do macrophages do?

Answer 23

Remove cell debris

Question 24

What does high tension in muscle cause?

Answer 24

Structural damage to muscle, cell membrane

Question 25

What are the 3 factors that results from loss of strength?

Answer 25

1.Physical disruption of muscle
2.Failure in execution-contraction coupling
3. Loss of contractile protein

Question 26

What 3 stages can reduce DOMS?

Answer 26

1. Minimize eccentric work early in training
2. Start with low intensity and increase gradually
3. Start with high-intensity, exhaustive training

Question 27

What does EAMC stand for?

Answer 27

Exercise-associated muscle cramps

Question 28

What are heat cramps?

Answer 28

Often associated with large sweat electrolyte losses, especially sodium and chloride