fatigue

Question 1

fatigue

Answer 1

less than anticipated response for a given stimulus
- no one cause of fatigue

Question 2

catastrophe theory

Answer 2

failure of one enzyme, system, cell, tissue, organ, or system places an undue burden on related systems such that several may begin to fail simultaneously

Question 3

what is the reasoning behind the catastrophe theory

Answer 3

• since multiple organs and organ systems are integrated hard to tell when and which one fails
• body and functions have genetic components from past lifestyles

Question 4

central fatigue

Answer 4

• fatigue within the nervous system, nervous discharge, not enough glucose (physiological signals –> psychological inhibition)
• painful afferent inputs from muscles + joints might affect continuing exercise
• increase in [H+] –> change in pH –> feel pain –> central fatigue

Question 5

what kind of movements contribute to central fatigue

Answer 5

compound movements

Question 6

possible theories behind the central fatigue theory

Answer 6

• hypoglycemia
• dehydration
• NE, dopamine, serotonin levels in the brain

Question 7

hypoglycemia theory to central fatigue

Answer 7

prolonged moderate to high intensity endurance exercise causes liver glycogen depletion

Question 8

dehydration theory to central fatigue

Answer 8

compromises mental functions like processing cognition, memory

Question 9

NE, dopamine, and seratonin levels in the brain

Answer 9

these hormones help to control mood and sleep
- catecholamines like NE and dopamine are synthesized from tyrosine and seratoning from tryptophan
- prolonged exercise increases tyrosine and tryptophan in the brain
- increases synthesis of NE, dopamine, seratonin + excessive cortisol = sense of drowsiness

Question 10

tyrosine

Answer 10

• the main amino acid that makes you sleepy
• takes a while to clear

Question 11

tryptophan

Answer 11

amino acid that also affects sleepyness

Question 12

peripheral fatigue

Answer 12

muscles begin to fail

Question 13

what contribues to peripheral fatigue

Answer 13

• general skeletal muscle relaxation
• membrane properties
• metabolite depletion
• metabolite accumulation

Question 14

how does muscle relaxation affect peripheral fatigue

Answer 14

• fatigue and muscle relaxation
• force frequency relationship
• force-pCa2+ relationshipwhat

Question 15

what is the fatigue and msucle relaxation correlation in regards to peripheral fatigue

Answer 15

• relaxation is slowed with fatigue (increases the half relaxation time)
• can lead to greater summation at a given frequency of activation
• also reduced force generating capacity

Question 16

what is true peripheral fatigue

Answer 16

reduced performance
- can also be a result of leaky SR

Question 17

force frequency relationship in regard to peripheral fatigue

Answer 17

• low frequency fatigue = depressed force @ lower frequencies of activation (maximal force isn’t affected)
• high frequency fatigue = depresses forced at higher frequencies and normal at low

Question 18

which is mor common low frequency fatigue or high frequency fatigue and why

Answer 18

low frequency fatigue bc its more physioligcally possible

Question 19

force pCa2+ relationship in regards to peripheral fatigue

Answer 19

• fatigue muscle has decreased Ca2+ sensitivity due to damaged troponin + tropomyosin
• Ca2+ elicits lesser force than in fresh muscle

Question 20

membrane properties in relation to peripheral fatigue

Answer 20

• hard working muscles have large extracellular [K+] = lots of AP generated by muscle fiber unable to rapidly restore [K+] gradient across sarcolemma
• changes RMP = harder excitability

Question 21

what metabolites are depleted in relation to peripheral fatigue

Answer 21

depletion in phosphagens, glycogen, and blood glucosew

Question 22

how does depletion of phosphagens affect peripheral fatigue

Answer 22

• ATP is high energy intermediate that supports muscle contraction + other things
• the immediate source of ATP dephosphorylation is CP
• during fatiguing exercise muscle CP levels decline (first rapid then slow)
• tension development and point of fatigue in isometric exercises coincide in CP depletion while ATP remain relatively maintained

Question 23

why is CP related to fatigue

Answer 23

• ATP is compartmentalized: decrease in one area doesn’t mean decrease in all areas
• ATP is extremely important so to protect itself muscle cells down regulate functions

Question 24

glycogen and metabolism depletion

Answer 24

• depletion seen to be correlated during prolonged submaximal exercise
• uniform glycogen depletion during moderate load cycling at moderate pedal rate in different muscle fibers
• low load cycling @ rapid rate = depletion in slow twitch fibers
• high load cycling @ lower pedal rate = glycogen depletion from fast twitch muscles

Question 25

blood glucose depletion and peripheral fatigue

Answer 25

- if glyvogen foes down during exercise blood glucose rises above pre exercise levels (stimulated by ANS) - limited by the ability of the liver to maintain high rates of glucose release limited by glycogen stores, heptaic glygenolytic and glucogenic enzymes

Question 26

metabolic accumulation and peripharl fatigue

Answer 26

- lactic acid - calcium ions - mitochondrial couploing efficiency - ryanodine receptor fatigue

Question 27

lactic acid accumlation and peripheral fatigue

Answer 27

- lactic acid accumulation seem during short term high intensity exercise - buildup occurs bc production is greater than removal - lactic acid dissociates a proton @ physiological pH = decrease in pH = increase in intramuscular bicarb stores to address increase in H+

Question 28

how does lower pH affect function within the muscle

Answer 28

- inhibits PFK and slows glycolysis - can stimulate pain receptors - affect the frequency + duration of Ca2+ channels being open - H+ can displace Ca2+ from troponin interfering with contraction - can inhibit myosin ATPase = decrease in power output

Question 29

calcium ion accumulation and peripheral fatigue

Answer 29

- Ca2+ loss from SR during excitation-contraction coupling taken up by mitochondria = interfering with mitochondria function - SR ability to release Ca2+ is slowed = reduced intracellular signal for contraction - causes a decrease in sensitity to Ca2+ for actin + myosin = decrease force production - reuptake is also slowed due to depressed SERCA

Question 30

is Ca2+ in the mitochondria bad

Answer 30

- in large amounts yes, but in small amounts may be good - helps to stimulate dehydrogenase in TCA cycle - but Ca2+ excretion uses ATP so O2 is consumed which affects mitochondrial energy potential fo phosphorylation ADP

Question 31

how is the ryanodine receptor affected during Ca2+ accumulation

Answer 31

- decreases force generation related to ryanodine receptors release of Ca2+ - lactate ion interferes = decrease in Ca2+ release