Chapter 13

Question 1

Plasticity?

Answer 1

muscle fibers adapt to the habitual level of demand placed on them

Question 2

Adaptation is a process of ________.

Answer 2

Remodeling

-form new mitochondria, more enzymes, more capillaries, more proteins

Question 3

Remodeling occurs as long as ______.

Answer 3

training stimulus occurs

Question 4

What makes the remodeling process more efficient?

Answer 4

when there is optimal nutrition and rest

Question 5

T/F

All fiber types undergo some training adaptation.

Answer 5

True

Question 6

Hypertrophy?

Answer 6

the CSA of muscle will enlarge due to an enlargement of the individual muscle fibers

Question 7

What causes hypertrophy?

Answer 7

chronic exercise training, caused mainly by resistance training but is also affected by aerobic exercise

Question 8

Myogenesis?

Answer 8

development of muscle tissue occurs during embyronic development, postnatal muscle growth, and as a mature adult

Question 9

What cells play an important role in the growth of adult skeletal muscle resulting from physical training?

Answer 9

Myogenic precursor cells (satellite cells)

Question 10

What activates satellite cells?

Answer 10

activated in response to muscle damage from injury, stretching, exercise

Question 11

How do satellite cells repair muscle damage?

Answer 11

they donate their nuclei to the fibers, which helps them regenerate fiber, growth of CSA, not length

Question 12

What fiber type has a greater number of satellite cells? why?

Answer 12

• ST
• b/c of their greater number of capillaries
• ST fibers have a broad range of activities, needed more for repair

Question 13

How does the immune system respond the exercise?

Answer 13

Macrophages are attracted to the injured fiber, phagocytosis of debris, inflammation for repair and waste product removal

Question 14

How does hormonal response contribute to hypertrophy?

Answer 14

• cortisol is released from adrenal cortex, stimulates the breakdown of proteins, increases the availability of amino acids for other functions
• growth hormone stimulates IGF which promotes satellite cell activation
• testosterone increases protein synthesis

Question 15

The hypertrophy of skeletal muscle following exercise induced overload is a result of the combined effects of what?

Answer 15

immune, hormone, growth factor, satellite cells

Question 16

What increases does hypertrophy cause?

Answer 16

• size of fibers
• number of myofibrils
• amount of actin, myosin
• cytoplasm
• capacity to exert force

Question 17

Hyperplasia?

Answer 17

increase in CSA due to an increased number of fibers

Question 18

What causes hyperplasia?

Answer 18

activated satellite cells fuse together forming new fibers instead of fusing with existing fibers (hypertrophy)

Question 19

What is the accepted mechanism in humans for increase in muscle mass?

Answer 19

hypertrophy

Question 20

Atrophy?

Answer 20

• decrease in CSA of fiber without a decrease in number of fibers
• reduced protein synthesis, increased protein breakdown
• it is reversible

Question 21

What causes atrophy?

Answer 21

• inactivity
• aging
• immobilization due to injury
• chronic disease
• space flight

Question 22

Why do males increase muscle mass at puberty? why do females increase body fat at puberty?

Answer 22

• testosterone

- estrogen

Question 23

What causes the gender gap to narrow?

Answer 23

• when you look at strength in relative terms, not absolute

- differences in strength is due to differences in muscle mass, not function of fibers

Question 24

What happens to fiber type with aging?

Answer 24

reduce type II, increase type I due to loss of high threshold motor neurons

Question 25

Muscle power declines ______ than muscle strength with advancing age.

Answer 25

earlier

Question 26

As humans age, there is an ______ in connective tissue in skeletal muscle and a ______ in muscle fibers.

Answer 26

increase | decrease

Question 27

What can reduce sarcopenia?

Answer 27

regular exercise to develop strength

Question 28

What are three neural adaptations to training?

Answer 28

1. motor unit recruitment- increased 2. motor unit synchronization- coordinated firing 3. rate coding- increase frequency

Question 29

Strength training is associated with what muscle adaptation?

Answer 29

- hypertrophy | - increased muscle mass

Question 30

Aerobic training is associated with what muscle adaptation? what others?

Answer 30

- mitochondrial biogenesis- increased mitochondrial number and mass - oxidative enzyme capacity - angiogenesis- increase capillaries - increase in myoglobin

Question 31

Can muscle fibers change type?

Answer 31

fibers lie on a continuum so they are able to transform from one type to another

Question 32

What is the general adaptation in fiber type as a result of training?

Answer 32

- decrease in hybrid types and an increase in pure types | - sedentary = hybrid types

Question 33

Which type will adapt the least?why?

Answer 33

IIx | b/c they are least abundant and least recruited

Question 34

Aerobic exercise results in increases of what fiber types?

Answer 34

- type I and decrease in hybrid types | - fast to slow adaptation

Question 35

What improvements will be seen with aerobic training?

Answer 35

- max amount of oxygen that can be utilized (VO2 max) | - increase in lactate threshold and performance

Question 36

Interval training?

Answer 36

- repeated bouts of high intensity exercise for brief periods - usually aerobic - no visible hypertrophy

Question 37

What is the benefit of interval training?

Answer 37

time efficient strategy to induce training adaptations normally associated with endurance training

Question 38

Initial increases in muscular strength and endurance during the 1st eight weeks of resistance training is due to what?

Answer 38

neural adaptations

Question 39

When does hypertrophy occur after starting resistance training?

Answer 39

first 4-8 weeks

Question 40

What is needed for maximal muscle fiber recruitment, hypertrophy, and strength gains when doing resistance training?

Answer 40

progressive overload

Question 41

There is a _____ correlation between muscle strength and CSA.

Answer 41

strong

Question 42

What causes increased muscle strength without increasing CSA?

Answer 42

neural factors

Question 43

Resistance training results in increases of what fiber types?

Answer 43

- increase in IIa - reduction in hybrid IIa/IIx types - slow to fast adaptation

Question 44

What is the progression in strength adaptation throughout the training process?

Answer 44

- 1st week- neural adaptations - up to 4th week- increase in Desmin - after 4th week- increase CSA - after 8th week- increase myosin heavy chain expression

Question 45

What results from detraining, physical inactivity?

Answer 45

- atrophy - reduction of adaptations gained - decrease in capillaries - decrease in mitochondria number and size in as little as one to two weeks

Question 46

What causes increase in type IIx fibers?

Answer 46

- removal of exercise stimulus | - bed rest

Question 47

Why do type IIx fibers increase when inactive?

Answer 47

it is the default fiber type b/c preserving its functional characteristics following periods of detraining maintains a functional reserve and an ability to respond to fight or flight situations