Fatigue

Question 1

How is fatige defineid in exercise science?

Answer 1

A process involving an exercise-induced reduction in the ability to exert muscle force or power

Question 2

What are the two main categories or fatigue?

Answer 2

Central
Peripheral

Question 3

What is peripheral fatigue?

Answer 3

Fatigue from changes at or distal to the neuromuscular junction

Question 4

What is central fatigue?

Answer 4

A reduction in neural drive to the muscles, not due to muscle contractility changes

Question 5

What are key metabolic causes of peripheral fatigue?

Answer 5

Substrate depletion and accumulation of deleterious metabolites

Question 6

What activation falure can cause peripheral fatigue?

Answer 6

Impaired actin potential propagation

Question 7

What are four key outcomes of peripheral fatigue?

Answer 7

Changes in [Ca2+]
Myofibrillar function
Shortening velocity
Relaxation time

Question 8

What phosphagens are linked to short, high-intensity fatigue?

Answer 8

ATP
Phosphocreatine (PCr)

Question 9

What happens when PCr is depleted?

Answer 9

ATP regeneration is limited, leading to fatigue

Question 10

What reaction helps buffer H+ during ATP resynthesis?

Answer 10

ADP + PCr + H+ <–> ATP + Cr

Question 11

How long can glycogen support moderate exercise?

Answer 11

1.5-2 hours

Question 12

What happens when glycogen is depleted?

Answer 12

Reliance on protein breakdown and reduced performance

Question 13

How can glycogen depletion be offset?

Answer 13

Lactate suttle
Liver glucose release
Carbohydrate loading

Question 14

What role does lactate plat in fatigue?

Answer 14

It allows glycolysis to continue but H+ accumulation can cause issues

Question 15

What does H+ do in muscle?

Answer 15

Inhibits PFK
Displaces Ca2+ on troponin
Stimulation pain receptors

Question 16

What effect does inorganic phosphate (Pi) have?

Answer 16

Inhibits cross-bridge formation and reduces calcium sensitivity

Question 17

What type of fatigue dominates a 100m sprint?

Answer 17

PCr depletion

Question 18

What type of fatigue dominates repeated sprints?

Answer 18

Metabolite accumulation

Question 19

What causes fatigue in a matathon?

Answer 19

Glycogen depletion

Question 20

What causes central fatigue?

Answer 20

Changes in neurotransmitters and afferent feedback reducing motor drive

Question 21

Why might central fatigue be beneficial?

Answer 21

It’s a protective mechanism - part of a negative feedback loop

Question 22

How can you test if fatigue is central or peripheral?

Answer 22

Induce muscle contraction via external action potentials without voluntary effort

Question 23

What is the sewuence from brian to force output?

Answer 23

Brain - Spinal cord - Peripheral nerve - Muscle sarcolemma - T-tubules - Ca2+ - Actin-Myosin - Cross-bridge - Force output

Question 24

What are common causes of muscle fatigue?

Answer 24

Substrate depletion
Muscle fibre damage
Build-up of metabolic by-products

Question 25

What is DOMS and when does it occur?

Answer 25

Delayed Onset Muscle Soreness 12-72 hours post-exercise

Question 26

What determines the ratio of fast glycolytic and slow oxidative muslce fibres?

Answer 26

Genetics

Question 27

What muscle fibre type is suited for sprinting and weight lifting?

Answer 27

Fast glycolytic (FG)

Question 28

What type of muscle fibre is ideal for endurance?

Answer 28

Slow oxidative (SO)

Question 29

How does aerobic training affect muscle fibres?

Answer 29

Converts some FG to fast oxidative glycolytic - increases mitochondrial volume and oxidative enzyme levels

Question 30

What are key mitochondrial adaptation to endurance training?

Answer 30

Larger mitochondria - increased number

Question 31

What happens to glycolytic enzymes?

Answer 31

Increases in enzymes like glycogen phosphorylase, phosphofructokinase, and LDH

Question 32

Which oxidative enzymes increase with training?

Answer 32

Citrate synthase Cytochrome c oxidase

Question 33

Do these enzymes becone more efficient?

Answer 33

No - they increase in number, not efficiency

Question 34

How does endurance trianing affect fat metabolsim?

Answer 34

Increases fat oxidation at rest and during submaximal exercise

Question 35

How does it affect carbohydrate metabolsim?

Answer 35

Increases CHO oxidation during max exercise - enchances glycogen storage

Question 36

What other physiological changes occur with endurance training?

Answer 36

Improved ionic balance Better lactate/H+ regulation Neural and cardiovascular adaptations

Question 37

What vascular change improves nutrient delivery?

Answer 37

Increased capillaristion

Question 38

How does postnatal muscle growth occur?

Answer 38

Via hypertrophy - enlargment of existing fibres

Question 39

What causes muscle atrophy?

Answer 39

Disease or denervation (nerve damage)

Question 40

What happens in long-term denervation?

Answer 40

Muscle shrinks to 25% of size and becomes connective tissue (6-24 month)

Question 41

What is a benefit of muscle hypertrophy?

Answer 41

Greater strength from more corss-bridges

Question 42

What is a downisde of muscle hypertrophy?

Answer 42

Increased diffusion distance for nutrients and waste

Question 43

What causes tetnus?

Answer 43

Infection by Clostridium tetani producing the neurotoxin tetanospasmin

Question 44

How does tetanospasmin affect the body?

Answer 44

Blocks inhibitory neurotransmitter release in the spinal cord --> uncontrolled excitation --> spasms

Question 45

What is msucle is usually affected first in tetanus?

Answer 45

The jaw

Question 46

What is Duchenne Muscular Dystrophy (DMD)?

Answer 46

A fatal, X-linked disorder Affects 1 in 3,500 males Caused by mutation in dystrophin

Question 47

What does dystrophin do?

Answer 47

Links actin to the extracellular matrix, stabilises muscle cell membranse during contration

Question 48

What happens without dystrophin?

Answer 48

Muscle cells break down under contraction stress and are replaced by connective tissue

Question 49

What is Distal Arthrogryposis?

Answer 49

A congenital condition causing contractures in hands and feet

Question 50

What causes Distal Arthrogryposis?

Answer 50

Mutation in myosin, tropomyosin, troponin, or myosin-binding protein C

Question 51

What is contracture?

Answer 51

Immobility from stiffness/constriciton in connective tissue

Question 52

What structural changes occur from resistance training?

Answer 52

Increases in myofibril, mitochondrial, sarcoplasmic reticulum, and organelles

Question 53

What causes strength increases with resistance training?

Answer 53

Hypertrophy (more contractile proteins) and neural adaptations