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KNSS 202: Exercise Physiology > Midterm Review > Flashcards

Midterm Review Flashcards

1
Q

Name the steps of muscle fibre contraction: excitation-contraction coupling.

A
  1. Action potential (AP) starts in brain
  2. AP arrives at axon terminal, releases acetylcholine (ACh)
  3. ACh crosses synapse, binds to ACh receptors on plasmalemma
  4. AP travels down plasmalemma, T-tubules
  5. Triggers Ca2+ release from sarcoplasmic reticulum (SR)
  6. Ca2+ enables actin-myosin contraction
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2
Q

How do muscles create movement?

A

process of actin-myosin contraction

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3
Q

Describe what happens during relaxed state.

A
  • No actin-myosin interaction at binding site

- Myofilaments overlap a little

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4
Q

Describe what happens during contracted state.

A
  • Myosin head pulls actin toward sarcomere center (power stroke)
  • Filaments slide past each other
  • Sarcomeres, myofibrils, muscle fiber all shorten
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5
Q

Describe what happens after power stroke ends.

A
  • Myosin detaches from active site
  • Myosin head rotates back to original position
  • Myosin attaches to another active site farther down
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6
Q

The muscle filament process continues until:

A
  • Z-disk reaches myosin filaments or

- AP stops, Ca2+ gets pumped back into SR

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7
Q

What energy is used for muscle contraction?

A

adenosine triphosphate (ATP)

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8
Q

What does ATP bind to for muscle contraction?

A
  • binds to myosin head
  • ATPase on myosin head
  • ATP –> ADP + Pi + energy
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9
Q

What happens when AP ends?

A

electrical stimulation of SR stops

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10
Q

What is pumped back into SR for muscle relaxation? What happens with it? What is required?

A
  • Ca 2+
  • stored until next AP arrives
  • requires ATP
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11
Q

What happens without Ca2+ for muscle relaxation?

A
  • troponin and tropomyosin return to resting conformation
  • Covers myosin-binding site
  • Prevents actin-myosin cross-bridging
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12
Q

Approx. 50% of fibres in an average muscle are what type?

A

type 1

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13
Q

Type 1 muscle fibres hit peak tension in how long?

A

110 ms (slow twitch)

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14
Q

Type 2 muscle fibres hit peak tension in how long?

A

50 ms (fast twitch)

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15
Q

Type 2 muscle fibres make up what percent of fibres in an average muscle each?

A

appox. 25%

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16
Q

What varies between type 1 and type 2 muscle fibres?

A

speed of myosin ATPase

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17
Q

Fast myosin ATPase =

A

fast contraction cycling

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18
Q

Slower myosin ATPase =

A

slower contraction cycling

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19
Q

What happens during a muscle biopsy?

A
  • Small (10-100 g) piece of muscle removed

- Frozen, sliced, examined under microscope

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20
Q

What is gel electrophoresis?

A
  • Type I versus II fibers have different types of myosin

- Separates different types of myosin by size

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21
Q

How do type 1 and type 2 fibres vary in terms of SR?

A
  • Type II fibers have a more highly developed SR

- Faster Ca2+ release, 3 to 5 times faster Vo

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22
Q

How do type 1 and type 2 fibres vary in terms of motor units?

A
  • Type I motor unit: smaller neuron, <300 fibers

- Type II motor unit: larger neuron, >300 fibers

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23
Q

What are the 2 types of muscle contraction?

A
  • static (isometric) contraction

- dynamic contraction

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24
Q

Describe static (isometric) contraction.

A
  • Muscle produces force but does not change length
  • Joint angle does not change
  • Myosin cross-bridges form and recycle, no sliding
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25
Q

Describe dynamic contraction.

A
  • Muscle produces force and changes length

- Joint movement produced

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26
Q

Describe motor unit recruitment for type 1 and type 2 motor units.

A
  • type 1 motor units = less force
  • type 2 motor units = more force
  • fewer small fibres versus more large fibres
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27
Q

What are the 3 different frequency of stimulation (rate coding)?

A
  • twitch
  • summation
  • tetanus
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28
Q

What is the length-tension relationship?

A
  • Optimal sarcomere length = optimal overlap

- Too short or too stretched = little or no force develops

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29
Q

What is the speed-force relationship?

A
  • Concentric: maximal force development decreases at higher speeds
  • Eccentric: maximal force development increases at higher speeds
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30
Q

Define substrates.

A
  • Fuel sources from which we make energy (adenosine triphosphate [ATP])
  • Carbohydrate, fat, protein
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31
Q

Define bioenergetics.

A
  • Process of converting substrates into energy

- Performed at cellular level

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32
Q

Define metabolism.

A

chemical reactions in the body

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33
Q

How can we calculate energy release?

A

can be calculated from heat produced

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34
Q

1 calorie (cal) =

A

heat energy required to raise 1 g of water from 14.5 °C to 15.5 °C

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35
Q

1000 cal =

A

1 kcal = 1 Calorie (dietary)

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36
Q

What are substrates?

A
  • fuel for exercise
  • carbohydrate, fat, protein
  • carbon, hydrogen, oxygen, nitrogen
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37
Q

Energy from chemical bonds in food stored in what?

A

high energy compound ATP

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38
Q

Resting: ___% carbohydrate, ___% fat

A

50% carbohydrate, 50% fat

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39
Q

Exercise (short):

A

more carbohydrate

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40
Q

Exercise (long):

A

carbohydrate, fat

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41
Q

All carbohydrate converted to:

A

glucose

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42
Q

What happens with carbohydrate that have been converted to glucose?

A
  • 4.1 kcal/g; ~2,500 kcal stored in body
  • Primary ATP substrate for muscles, brain
  • Extra glucose stored as glycogen in liver, muscles
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43
Q

When is glycogen converted back to glucose?

A

when needed to make more ATP

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44
Q

Describe glycogen stores.

A
  • limited (2500 kcal)

- must rely on dietary carbohydrate to replenish

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45
Q

What is the energy substrate during starvation?

A

protein

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46
Q

What happens with protein used as energy?

A
  • 4.1 kcal/g

- Must be converted into glucose (gluconeogenesis)

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47
Q

Protein can also be converted into what? What is this used for?

A
  • FFAS (lipogenesis)
  • For energy storage
  • For cellular energy substrate
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48
Q

Energy is released at a controlled rate based on what?

A
  • availability of primary substrate

- enzyme activity in metabolic pathway

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49
Q

What is the mass action effect?

A
  • Substrate availability affects metabolic rate
  • More available substrate = higher pathway activity
  • Excess of given substrate = cells rely on that energy substrate more than others
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50
Q

Name 4 characteristics of enzymes.

A
  • Do not start chemical reactions or set ATP yield
  • Do facilitate breakdown (catabolism) of substrates
  • Lower the activation energy for a chemical reaction
  • End with suffix -ase
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51
Q

ATP is broken down by:

A

ATPase

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52
Q

Enzymes determine ____ yield.

A

ATP yield

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53
Q

Each step in a biochemical pathway requires specific ______.

A

enzyme(s)

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54
Q

More enzyme activity =

A

more product

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55
Q

What is rate-limiting enzyme?

A
  • Can create bottleneck at an early step
  • Activity influenced by negative feedback
  • Slows overall reaction, prevents runaway reaction
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56
Q

Why must the body constantly synthesize new ATP?

A

ATP storage is limited

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57
Q

What are the 3 ATP synthesis pathways?

A
  • ATP-PCr system (anaerobic metabolism)
  • Glycolytic system (anaerobic metabolism)
  • Oxidative system (aerobic metabolism)
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58
Q

What type of system is the ATP-PCr system?

A
  • anaerobic

- substrate level metabolism

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59
Q

What is the duration of the ATP-PCr system?

A

3 to 15s

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60
Q

What pathway is used to reassemble ATP because ATP stores are very limited?

A

ATP-PCr system

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61
Q

How does phosphocreatine (PCr): ATP recycling work?

A
  • PCr + creatine kinase –> Cr + Pi + energy
  • PCr energy cannot be used for cellular work
  • PCr energy can be used to reassemble ATP
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62
Q

The ATP-PCr system replenishes what?

A

ATP stores during rest

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63
Q

The ATP-PCr system recycles ATP during _____ until _____.

A

recycles ATP during exercise until used up (~3-15 s maximal exercise)

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64
Q

What type of system is the glycolytic system?

A

anaerobic

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65
Q

What is the duration of the glycolytic system?

A
  • 15s to 2 min.

- need another pathway for longer durations

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66
Q

The glycolytic system is the breakdown of ______.

A

glucose via glycolysis

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67
Q

How does the glycolytic system use glucose or glycogen as its substrate?

A
  • Must convert to glucose-6-phosphate

- Costs 1 ATP for glucose, 0 ATP for glycogen

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68
Q

The glycolytic system pathway starts with ____, ends with _____.

A

starts with glucose-6-phosphate, ends with pyruvic acid\

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69
Q

The glycolytic system has how many enzymatic reactions total?

A

10-12

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70
Q

Where does the glycolytic system occur?

A

all steps occur in cytoplasm

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71
Q

What is the ATP yield for glycolytic system?

A
  • 2 ATP for glucose

- 3 ATP for glycogen

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72
Q

What are the pros of the glycolytic system?

A
  • Allows muscles to contract when O2 limited

- Permits shorter-term, higher-intensity exercise than oxidative metabolism can sustain

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73
Q

What are the cons of the glycolytic system?

A
  • Low ATP yield, inefficient use of substrate
  • Lack of O2 converts pyruvic acid to lactic acid
  • Lactic acid impairs glycolysis, muscle contraction
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74
Q

What is Phosphofructokinase (PFK)?

A
  • rate limiting enzyme
  • dec. ATP (inc. ADP) –> inc. PFK activity
  • inc. ATP –> dec. PFK activity
  • also regulated by products of Krebs cycle
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75
Q

Glycolysis will give you ~ ___ min maximal exercise.

A

~2 minutes

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76
Q

What type of system is the oxidative system?

A

aerobic

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77
Q

What is the ATP yield of the oxidative system?

A
  • depends on substrate
  • 32 to 33 ATP/1 glucose
  • 100+ ATP/1 FFA
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78
Q

What is the duration of the oxidative system?

A

steady supply for hours

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79
Q

Which is the most complex of the 3 bioenergetic systems?

A

oxidative system

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80
Q

Where does the oxidative system occur?

A

in the mitochondria, not cytoplasm

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81
Q

What are the 3 stages of oxidation of carbohydrate?

A
  • Stage 1: Glycolysis
  • Stage 2: Krebs cycle
  • Stage 3: Electron transport chain
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82
Q

Which systems interact for all activities?

A
  • all 3 systems
  • no one system contributes 100%
  • one system often dominates for a given task
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83
Q

Type 1 fibres have _____ oxidative capacity. Why?

A
  • greater
  • more mitochondria
  • high oxidative enzyme concentrations
  • type II better for glycolytic energy production
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84
Q

Describe how endurance training effects fibre type composition.

A
  • enhances oxidative capacity of type II fibres
  • develops more (and larger) mitochondria
  • more oxidative enzymes per mitochondrion
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85
Q

As intensity goes up, so does …

A

ATP demand

86
Q

What happens in response to increased intensity?

A
  • Rate of oxidative ATP production increases
  • O2 intake at lungs increases
  • O2 delivery by heart, vessels increases
87
Q

O2 storage is limited, meaning:

A

use it or lose it

88
Q

What is a accurate estimate of O2 use in muscle?

A

O2 levels entering and leaving the lungs

89
Q

The sensory division transmits information from ______ to _____.

A

periphery to brain

90
Q

What are the 5 major families of sensory receptors?

A
  • Mechanoreceptors: physical forces
  • Thermoreceptors: temperature
  • Nociceptors: pain
  • Photoreceptors: light
  • Chemoreceptors: chemical stimuli
91
Q

Name 3 special families of sensory receptors.

A
  • joint kinesthetic receptors
  • muscle spindles
  • golgi tendon organs
92
Q

Joint kinesthetic receptors are sensitive to:

A

joint angles, rate of angle change

93
Q

Joint kinesthetic receptors sense:

A

joint position, movement

94
Q

Muscle spindles are sensitive to:

A

muscle length, rate of length change

95
Q

Muscle spindles sense:

A

muscle stretch

96
Q

Golgi tendon organs are sensitive to:

A

tension in tendon

97
Q

Golgi tendon organs sense:

A

strength of contraction

98
Q

The motor division transmits information from _____ to _____.

A

brain to periphery

99
Q

What are the 2 divisions of the motor division?

A
  • autonomic: regulates visceral activity

- somatic: stimulates skeletal muscle activity

100
Q

The autonomic nervous system controls:

A

involuntary internal functions

101
Q

Name some exercise-related autonomic regulation.

A
  • HR, BP

- lung function

102
Q

What are the 2 complementary divisions of the autonomic nervous system.

A
  • sympathetic nervous system

- parasympathetic nervous system

103
Q

Describe the sympathetic division of the autonomic nervous system.

A
  • fight or flight

- prepares body for exercise

104
Q

Sympathetic stimulation results in:

A
  • increased HR, BP
  • increased blood flow to muscles
  • increased airway diameter (bronchodilation)
  • increased metabolic rate, glucose levels, FFA levels
  • increased mental activity
105
Q

Describe the parasympathetic division of the autonomic nervous system.

A
  • rest and digest
  • active at rest
  • opposes sympathetic effects
106
Q

Parasympathetic stimulation results in:

A
  • increased digestion, urination
  • conservation of energy
  • decreased heart rate
  • decreased diameter of vessels and airways
107
Q

A _____ ______ carries AP to muscle.

A

motor neuron

108
Q

AP spreads to _____ ______ of motor unit.

A

muscle fibres

109
Q

Fine motor control means _____ fibres per motor unit.

A

fewer

110
Q

Gross motor control means _____ fibres per motor unit.

A

more

111
Q

Describe the homogeneity of motor units.

A
  • Fiber types not mixed within a given motor unit
  • Either type I fibers or type II fibers
  • Motor neuron may actually determine fiber type
112
Q

Nervous system = ______ communication.

A

electrical

113
Q

Endocrine system = ______ communication.

A

chemical

114
Q

The endocrine system is _____ responding and _____ lasting than the nervous system.

A
  • slower responding

- longer lasting

115
Q

The endocrine system maintains homeostasis via ______.

A

hormones

116
Q

What are hormones?

A
  • chemicals that control and regulate cell/organ activity

- act on target cells

117
Q

The endocrine system constantly monitors ____ ____.

A

internal environment

118
Q

The endocrine system coordinates…

A

integration of physiological systems during rest and exercise

119
Q

The endocrine system maintains ______ during exercise.

A

homeostasis

120
Q

How does the endocrine system maintain homeostasis during exercise?

A
  • controls substrate metabolism

- regulates fluid, electrolyte balance

121
Q

______ is appetite control centre of brain.

A

hypothalamus

122
Q

Satiety centre is in _____ _____.

A

ventromedial nucleus

123
Q

Hunger centre is in _____ _____.

A

lateral hypothalamus

124
Q

___ _____ releases hormones that affect hunger signals.

A

GI tract

125
Q

What is cholecyctokinin (CCK)?

A
  • stimulated when stomach is full

- decreases appetite

126
Q

What is glucagon-like peptide (GLP-1)?

A
  • released in small intestine

- decreases appetite

127
Q

What is peptide YY (PYY)?

A
  • released in small intestine

- decreases appetite

128
Q

What is ghrelin?

A

increases appetite

129
Q

Adipose is an _____ organ.

A

endocrine

130
Q

Leptin is released from where? What does it do?

A
  • released from adipose stores

- reduces hunger

131
Q

Leptin and ghrelin act in _______ ways.

A

opposing

132
Q

Obese people have higher ____. Why doesn’t this work properly?

A
  • leptin

- resistant to effects

133
Q

*_____ affects hunger and satiety hormones.

A

exercise

134
Q

*Acute, vigorous exercise increases ____ and ___, doing what to hunger?

A
  • PYY and GLP-1

- reducing hunger

135
Q

*How does exercise training affect ghrelin?

A

does not affect it except in energy deficit

136
Q

Looking at substrate metabolism efficiency, 40% of substrate energy –>

A

ATP

137
Q

Looking at substrate metabolism efficiency, 60% of substrate energy –>

A

heat

138
Q

Heat production increases with _____ production.

A

energy

139
Q

How can energy expenditure be measured with direct calorimetry?

A
  • Can be measured in a calorimeter
  • Water flows through walls
  • Body temperature increases water temperature
140
Q

What are the pros of measuring energy expenditure with direct calorimetry?

A
  • Accurate over time

- Good for resting metabolic measurements

141
Q

What are the cons of measuring energy expenditure with direct calorimetry?

A
  • Expensive, slow
  • Exercise equipment adds extra heat
  • Sweat creates errors in measurements
  • Not practical or accurate for exercise
142
Q

How can energy expenditure be measured indirectly?

A
  • estimate total body energy expenditure based on O2 used, CO2 produced
  • measures respiratory gas concentrations
  • only accurate for steady-state oxidative metabolism
143
Q

Older methods of measuring energy expenditure indirectly are ______ but ____.

A

accurate but slow

144
Q

New methods of measuring energy expenditure indirectly are ______ but ____.

A

faster but expensive

145
Q

What is VO2?

A
  • volume of O2 consumed per minute
  • rate of O2 consumption
  • volume of inspired O2 [minus] volume of inspired CO2
146
Q

What is VCO2?

A
  • volume of CO2 produced per minute
  • rate of CO2 production
  • volume of expired CO2 [minus] volume of inspired CO2
147
Q

What are 3 ways of measuring energy expenditure?

A
  • directly
  • indirectly
  • respiratory exchange ratio
148
Q

O2 usage during metabolism depends on…

A

type of fuel being oxidized

149
Q

More carbon atoms in molecule =

A

more O2 needed

150
Q

Glucose (C6H12O6) < ______

A

palmitic acid (C16H32O2)

151
Q

What is the respiratory exchange ratio (RER)?

A
  • Ratio between rates of CO2 production, O2 usage

- RER = VCO2 / VO2

152
Q

RER for 1 molecule glucose =

A

1.0

153
Q

Work out why RER for 1 molecule glucose is 1.0.

A
  • 6 O2 + C6H12O6–> 6 CO2 + 6 H2O + 32 ATP

- RER = VCO2 / VO2 = 6 CO2/6 O2 = 1.0

154
Q

RER for 1 molecule palmitic acid =

A

0.70

155
Q

Work out why RER for 1 molecule palmitic acid is 0.70.

A
  • 23 O2 + C16H32O2 –> 16 CO2 + 16 H2O + 129 ATP

- RER = VCO2 / VO2 = 16 CO2/23 O2 = 0.70

156
Q

The RER predicts:

A
  • substrate use

- kilocalories/O2 efficiency

157
Q

Name 4 indirect calorimetry limitations.

A
  • CO2 production may not = CO2 exhalation
  • RER inaccurate for protein oxidation
  • RER near 1.0 may be inaccurate when lactate buildup ( ) CO2 exhalation
  • Gluconeogenesis produces RER <0.70
158
Q

What is metabolic rate?

A

rate of energy use by body

159
Q

Based on whole-body O2 consumption and corresponding caloric equivalent, what is RER at rest?

A

~0.80

160
Q

Based on whole-body O2 consumption and corresponding caloric equivalent, what is VO2 at rest?

A

~0.3 L/min

161
Q

Based on whole-body O2 consumption and corresponding caloric equivalent, what is metabolic rate at rest?

A

~2000 kcal/day

162
Q

What is basal metabolic rate (BMR)?

A

rate of energy expenditure at rest

163
Q

When is BMR taken?

A
  • In supine position
  • Thermoneutral environment
  • After 8 h sleep and 12 h fasting
164
Q

Minimum energy requirement for living is related to…

A

fat-free mass (kcal x kg FFM^-1 x min^-1)

165
Q

Name 5 factors that affect BMR.

A
  • body SA
  • age
  • stress
  • hormones
  • body temperature
166
Q

What is resting metabolic rate (RMR)?

A
  • Similar to BMR (within 5-10% of BMR) but easier
  • Doesn’t require stringent standardized conditions
  • 1,200 to 2,400 kcal/day
167
Q

Total daily metabolic activity includes…

A

normal daily activities

168
Q

What is the normal range for total daily metabolic activity?

A

1800 to 3000 kcal/day

169
Q

What is the total daily metabolic activity range for competitive athletes?

A

up to 10,000 kcal/day

170
Q

Metabolic rate increases with _____ _____.

A

exercise intensity

171
Q

Slow component of O2 uptake kinetics during submaximal aerobic exercise means:

A
  • At high power outputs, VO2 continues to increase

- More type II (less efficient) fiber recruitment

172
Q

What is VO2 drift?

A
  • Upward drift observed even at low power outputs

- Possibly due to ventilatory, hormone changes?

173
Q

What is VO2 max?

A
  • maximal O2 uptake
  • Point at which O2 consumption doesn’t increase with further increase in intensity
  • Best single measurement of aerobic fitness
  • Not best predictor of endurance performance
174
Q

When does VO2 max plateau?

A

after 8 to 12 weeks of training

175
Q

What allows athletes to compete at higher percentage of VO2 max?

A

more training

176
Q

VO2 max is expressed in:

A
  • L/min
  • easy standard units
  • suitable for non-weight-bearing activities
177
Q

What is the VO2 max for untrained young men?

A

44-50 L/min

178
Q

What is the VO2 max for untrained young women?

A

38-42 L/min

179
Q

Why is there a sex difference in VO2 max?

A

women’s lower FFM and hemoglobin

180
Q

Can any activity be 100% aerobic or anaerobic?

A

no

181
Q

Estimates of anaerobic effort involve:

A
  • excess postexercise O2 consumption

- lactate threshold

182
Q

What is postexercise O2 consumption?

A
  • O2 demand > O2 consumed in early exercise

- O2 consumed > O2 demand in early recovery

183
Q

If O2 demand > O2 consumed in early exercise, what happens?

A
  • Body incurs O2 deficit
  • O2 required − O2 consumed
  • Occurs when anaerobic pathways used for ATP production
184
Q

If O2 consumed > O2 demand in early recovery, what happens?

A
  • Excess postexercise O2 consumption (EPOC)

- Replenishes ATP/PCr stores, converts lactate to glycogen, replenishes hemo/myoglobin, clears CO2

185
Q

What is lactate threshold?

A

point at which blood lactate accumulation increases markedly

186
Q

When lactate threshold is reached, lactate production rate > ____ _____ ____.

A

lactate clearance rate

187
Q

Lactate threshold is an interaction of _____ and _____ systems.

A

aerobic and anaerobic

188
Q

Lactate threshold is a good indicator of …

A

potential for endurance exercise

189
Q

Lactate threshold is usually expressed as:

A

percentage of VO2 max

190
Q

Higher lactate threshold =

A

better endurance performance

191
Q

For 2 athletes with the same VO2 max, higher lactate threshold predicts…

A

better performance

192
Q

Why is anaerobic capacity hard to measure?

A

no clear, VO2 max like method for measuring anaerobic capacity

193
Q

Name 3 imperfect but accepted methods for measuring anaerobic capacity?

A
  • maximal accumulated O2 deficit
  • wingate anaerobic test
  • critical power test
194
Q

What are the 2 definitions of fatigue?

A
  • Decrements in muscular performance with continued effort, accompanied by sensations of tiredness
  • Inability to maintain required power output to continue muscular work at given intensity
195
Q

Fatigue is reversible by ____.

A

rest

196
Q

Fatigue can be caused by:

A
  • metabolic by-products

- muscle soreness

197
Q

How does heat alter metabolic rate?

A
  • increased rate of carbohydrate utilization
  • hastens glycogen depletion
  • high muscle temperature may impair muscle function
198
Q

At what temperature is time to exhaustion longest?

A

11 degrees celsius

199
Q

At what temperature is time to exhaustion shortest?

A

31 degrees celsius

200
Q

Muscle ______ prolongs exercise.

A

precooling

201
Q

Where does muscle soreness come from?

A

exhaustive or high-intensity exercise, especially the first time performing a new exercise

202
Q

When is muscle soreness felt?

A
  • can be felt anytime
  • acute soreness during and immediately after exercise
  • delayed-onset soreness one to two days later
203
Q

What is DOMS?

A

delayed-onset muscle soreness

204
Q

When is DOMS felt?

A

1-2 days after exercise bout

205
Q

What does DOMS feel like?

A

ranges from stiffness to severe, restrictive pain

206
Q

What is a major cause of DOMS? What is it not caused by? Give an example.

A
  • caused by eccentric contractions
  • ex. level run pain < downhill run pain
  • not caused by blood lactate concentrations
207
Q

Describe the sequence of events in DOMS.

A
  1. high tension in muscle = structural damage to muscle, cell membrane
  2. membrane damage disturbs Ca 2+ homeostasis in injured fibre
  3. after a few hours, circulating neutrophils
  4. products of macrophage activity, intracellular contents accumulate
  5. fluids and electrolytes shift into the area, creating edema
208
Q

What happens when membrane damage disturbs Ca 2+ homeostasis in injured fibre?

A
  • inhibits cellular respiration

- activates enzymes that degrade z-discs

209
Q

What happens when intracellular contents accumulate?

A
  • histamine, kinins, K+

- stimulate pain in free nerve endings

210
Q

DOMS = ______ muscle force generation

A

decreased

211
Q

DOMS results in loss of strength because of 3 factors:

A
  • physical disruption of muscle
  • failure in excitation-contraction coupling (appears to be most important)
  • loss of contractile protein
212
Q

Name 3 strategies to reduce DOMS.

A
  • Minimize eccentric work early in training
  • Start with low intensity and gradually increase
  • Start with high-intensity, exhaustive training (soreness bad at first, much less later on)

KNSS 202: Exercise Physiology (4 decks)

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