Chapter 14: The Physiology of Resistance Training

Question 1

Muscular strength

Answer 1

maximal force a muscle or muscle group can generate (1-RM)

Question 2

Muscular endurance

Answer 2

ability to make repeated contractions against a submaximal load

Question 3

High-resistance training (heavy weight, low reps) results in

Answer 3

gains in strength

Question 4

Low-resistance training (lighter weight, high reps) results in

Answer 4

gains in endurance

Question 5

Strength training results in

Answer 5

increase in muscle size and strength

Question 6

Strength gain in short term training (2-8 weeks)

Answer 6

Neural adaptations are responsible for early gains in strength gains

Question 7

Strength gain in long-term training (20+ weeks)

Answer 7

Increase in muscle size (hypertrophy) and fiber specific force are most important for long-term gains in strength

Question 8

How long does it take for muscle hypertrophy to occur?

Answer 8

Muscle hypertrophy increases during months or years of training

but, high-intensity resistance training can result in hypertrophy with 10 sessions (3 weeks)

Question 9

Compare endurance and resistance training induced CNS adaptations

Answer 9

endurance training —> no carry over effect of training to contralateral side of body

resistance training —> if one arm is trained, then the untrained contralateral arm receives strength gains (phenomenon called “cross-education”)

Question 10

Cross-education

Answer 10

trained side receives gains via hypertrophy and neural adaptations

untrained side receives gains via neural adaptations

Question 11

Neural adaptations in strength training include

Answer 11

1. increased motor units recruited
2. increased firing rate of motor units
   —–increased frequency of depolarization result in increased force production
3. increased motor unit synchronization
   —-simultaneous recruitment of numerous motor units resulting in increased force production
4. improved neural transmission across neuromuscular junction

Question 12

increased muscle fiber specific tension in type 1 fibers from resistance training due to

Answer 12

increased calcium sensitivity, which increases the number of cross bridges bound to actin

Question 13

Hypertrophy

Answer 13

increase in muscle fiber cross-sectional area

size of type I and II fibers increase but size of type II fibers increase more

Question 14

Hypertrophy is due to

Answer 14

increased actin and myosin because of the addition of sarcomeres in parallel of existing sarcomeres

Question 15

Hyperplasia

Answer 15

increase in muscle fiber number

• evidence supporting hyperplasia in animal studies but no conclusive evidence this happens in humans
• even if hyperplasia does occur in humans, it’s contribution to muscle mass is likely small

Question 16

Resistance training promotes changes in muscle fiber type

Answer 16

fast-to-slow shift in fiber type

from type IIx to IIa
- 5-11% change following 20 weeks of training
- no increase in type I fibers

lesser extent than endurance training

Question 17

Resistance training improves antioxidant capacity how?

Answer 17

100% increase in key antioxidant enzymes following 12 weeks of training

Question 18

Can resistance training improve muscle oxidative capacity and increase capillary number?

Answer 18

studies show conflicting results on mitochondrial content and capillary number… because of different frequency and duration of training

Question 19

Long-term, high frequency (3d/wk), high volume (high reps) training resulted in

Answer 19

small increases in muscle oxidative capacity and capillary number

Question 20

Muscle protein synthesis increases _____ 1 to 4 hours after a single bout of resistance training in trained and untrained individuals

Answer 20

50-150%

Question 21

How long does protein synthesis remain elevated?

Answer 21

30 to 48 hours, but depends on training status

– elevated longer in untrained individuals

Question 22

Key factors that contribute to resistance training-induced increases in muscle protein synthesis

Answer 22

• mRNA increases, resulting in protein synthesis at the ribosome
• ribosomes increase in number and elevate muscle’s protein synthesis capacity
• activation of the protein kinase “mechanistic target of rapamycin” (mTOR) is the key factor accelerating protein synthesis following a bout of resistance training

Question 23

Resistance training induced fiber hypertrophy results in

Answer 23

a parallel increase in muscle fiber size and number of myonuclei

increases myofibrillar proteins and fiber cross sectional area

Question 24

Resistance training activates satellite cells to

Answer 24

divide and fuse with adjacent muscle fibers to increase myonuclei

• addition of new myonuclei fibers increases protein synthesis in larger muscle fibers-essential to achieve maximal hypertrophy

Question 25

Resistance training induced increases in myonuclei results in

Answer 25

a constant ratio between number of myonuclei and size of muscle fiber

myonuclear domain remains constant

Question 26

Resistance training-induced satellite cell activation in older individuals

Answer 26

is blunted which limits resistance training-induced muscle hypertrophy

Question 27

testosterone, insulin-like growth factor-1 and growth hormone are linked to

Answer 27

mTOR activation and can increase muscle protein synthesis

though, these can occur independent of these hormones

Question 28

a bout of resistance training increases circulating levels of

Answer 28

testosterone, IGF-1 and growth hormone

Question 29

How much of the differences in muscle mass between individuals is due to genetic variation?

Answer 29

approximately 80%

Question 30

How many different genes are major contributors to muscle mass?

Answer 30

47

Question 31

Many hypertrophy-linked genes are directly linked to

Answer 31

the mTOR pathway and are activated via resistance training

Question 32

large differences exist in the magnitude of resistance training-induced skeletal muscle hypertrophy due to

Answer 32

variations in ability to activate specific “protein synthesis genes in skeletal muscle in response to resistance training

Question 33

Low responder

Answer 33

low genetic potential for hypertrophy

Question 34

Moderate-responder

Answer 34

moderate genetic potential for hypertrophy

Question 35

High-responder

Answer 35

high genetic potential for hypertrophy

Question 36

Do anti-inflammatory drugs impact resistance-training-induced hypertrophy?

Answer 36

• Animal studies suggest that these drugs blunt resistance training-induced muscle hypertrophy
• However, recent human studies reveal that these drugs do not negatively impact strength gains in humans

Short answer, no.

Question 37

How much of a decrease in strength is there following 30 weeks of detraining?

Answer 37

there is a slow decrease in strength

31% decrease

Question 38

Small changes in fiber size during detraining

Answer 38

• Type I fiber size– 2%
• Type IIa fiber size– 10%
• Type IIx fiber size– 14%

Question 39

The slow decrease in strength with detraining is primarily due to

Answer 39

nervous system changes

Question 40

Retraining results in

Answer 40

rapid regain of strength and muscle size

– within 6 weeks after resuming training

Question 41

Muscle memory

Answer 41

the ability for a rapid recovery

– the mechanism responsible for muscle memory remains controversial

Question 42

Recent research suggests that muscle memory is due to

Answer 42

resistance training-induced increases in myonuclei in the trained fibers that are not lost during detraining

– maintaining myonuclei provides advantage in rapid protein synthesis upon retraining

Question 43

Prolonged periods of muscle inactivity or unloading (bedrest, cast, space flight) results in

after 7 days…
20 to 30 days…

Answer 43

skeletal muscle atrophy

7 days—> 7 to 10% loss of muscle mass

20-30 days —> 15 to 20% reduction in muscle fiber size

Question 44

Conservation of muscle mass is dependent upon

Answer 44

balance between protein synthesis and rates of protein degradation.

Question 45

Inactivity-induced muscle atrophy occurs due to

Answer 45

decrease in muscle protein synthesis

increase in muscle protein breakdown

Question 46

Increased _______ promotes muscle atrophy during prolonged inactivity by depressing protein synthesis and increasing degradation

Answer 46

production of free radicals

– results in oxidative stress

Question 47

Strength training increases _____ whereas endurance training does not.

Answer 47

muscle fiber size

Question 48

Many studies conclude that concurrent strength and endurance training has what effect?

Answer 48

impairs strength gains, compared to strength training alone

– the impact of concurrent training on strength gains depends on intensity, volume, and frequency of endurance training