Lecture 10

Question 1

Lecture 10:

When muscle size increases, what happens to strength? When size decrease?

Answer 1

Increase in muscle size (hypertrophy) = increase in muscle strength

Decrease in muscle size (atrophy) = decrease in muscle strength

Question 2

Lecture 10:

What are 2 sources of strength gains?

Answer 2

1.) increase in muscle size
2.) altered neural control levels

Question 3

Lecture 10:

How does neural control impact strength gain?

Answer 3

Strength gain cannot occur without neural adaptations (via plasticity)
- strength gain also cant occur without hypertrophy
*strength is a property of the motor system not just the muscle

Question 4

Lecture 10:

What are essential elements of strength gain?

Answer 4

Neural Control, Motor unit recruitment, stimulation frequency, & other neural factors

Question 5

Lecture 10:

How are motor units recruited normally?

Answer 5

Normally recruited Asynchronously

Question 6

Lecture 10:

How are motor units recruited when wanting strength gains?

Answer 6

Synchronous recruitment allows for strength gains as it improves the muscles ability to generate force & rate of the force development
- facilitates more forceful contractions & capability to exert forces steadily

Question 7

Lecture 10:

What is another way motor units cause strength gains? (Other than type for recruitment)

Answer 7

Greater motor unit recruitment may cause strength gains as well due to increased neural drive on max contraction, increase ferquency of neural discharge & decreased inhibitory impulses

Question 8

Lecture 10:

What is an example for Autogenic Inhibition?

Answer 8

Normal intrinsic inhibitory mechanisms like; the Golgi tendon organs that inhibit muscle contraction when tendon tension’s too high so damage is prevented

Question 9

Lecture 10:

What occurs to inhibitory impulses when training?

Answer 9

Inhibitory impulses decreased by training so muscle can generate more force

Question 10

Lecture 10:

When discussing other neural factors of Muscle strength gain, how does coactivation alter this?

Answer 10

Reducing Co-activation of agonist & antagonist muscles causes strength gain as more strength can be produced as antagonists don’t oppose agonist force as much

Question 11

Lecture 10:

Define Muscle Hypertrophy

Answer 11

Increase in muscle size

Question 12

Lecture 10:

What are the 2 types of muscle hypertrophy?

Answer 12

Transient & Chronic

Question 13

Lecture 10:

what is Transient Hypertrophy?

Answer 13

1.) Transient - occurs after exercise due to edema formation from plasma fluid build up & doesn’t last long (gone in a few hours)

Question 14

Lecture 10:

What is Chronic Hypertrophy?
- 2 types?

Answer 14

2.) Chronic - long-term structural change in the muscle & is the actual structural changes of muscles
- can be fibre hypertrophy (each fibre gets bigger) or fibre hyperplasia (more fibres added to muscle)

Question 15

Lecture 10:

What type of training allows for maximized chronic muscle hypertrophy?

Answer 15

High-velocity eccentric training as it disrupts the sarcomere Z-lines (protein remodeling)
- concentric training may limit strength gain (hypertrophy)
- caused by both high-rep/low-load and low-rep/high-load training

Question 16

Lecture 10:

What physically happens to the muscle during fibre hypertrophy?

Answer 16

There are more myofibrils, more actin & myosin filaments, more sarcoplasm, & more connective tissue
- resistance training increases protein synthesis (synthesis decreased & degradation increased when exercising & opposite after exercise)

Question 17

Lecture 10:

What 3 hormones facilitate fibre Hypertrophy?

Answer 17

• Testosterone — (natural anabolic steroid) causes large increase in muscle mass
• Growth Hormone
• Insulin-like Growth Factor 1 (IGF-1)
  *elevated levels post exercise not required for anabolism & strength gain

Question 18

Lecture 10:

What types of animal studies were done for fibre hyperplasia?
- explain

Answer 18

1.) Cats - showed intense strength training produced fibre splitting as each half grows to size of parent
2.) Chickens,mice, & rats - didn’t see muscle fibre hyperplasia & intense training only caused fibre hypertrophy.

Question 19

Lecture 10:

When discussing neural activation & hypertrophy, what occurs during short-term increase in muscle strength?

Answer 19

Short-term increase in muscle strength leads to substantial increase in 1 rep max & occurs due to increased voluntary neural activation (neural factors critical in first 8-10weeks)

Question 20

Lecture 10:

When discussing neural activation & hypertrophy, what occurs during long-term increase in muscle strength?

Answer 20

Long-term increase in muscle strength is associated with significant fibre hypertrophy & a net increase in protein synthesis (requires time) - major factor after first 10weeks

Question 21

Lecture 10:

What is muscle atrophy & what occurs to muscles during inactivity?

Answer 21

Atrophy = major change in muscle structure & functions (decrease in muscles) & caused by reduced activity
- limb immobilization & retraining studies support this

Question 22

Lecture 10:

What occurred in the Limb Immobilization studies?
- after 6hours? First week?

Answer 22

• Major changes seen after 6h —> lack of muscle use caused reduced protein synthesis & muscle atrophy initiated
• First week (3-4% strength lost/day) —> decreased muscle size (atrophy) & decreased neuromuscular activity
• type I more effected than type II but both reversibke

Question 23

Lecture 10:

What does de training lead to?

Answer 23

Retraining = decreased 1 rep max but lost strength can be regained in ~6weeks
- meeting training goal = maintenance resistance prevents retraining - maintain strength & 1rm (even with reduced training frequency)

Question 24

Lecture 10:

What are a few conditions that allow fro fibre type conversion?

Answer 24

Fibre type conversion is possible under conditions like;
- cross-innervation
- chronic low-frequency stimulation
- high-intensity treadmill or resistance training

Question 25

Lecture 10:

What is the 20-week heavy resistance training program?

Answer 25

Program that helps with fibre type alterations
- static strength & cross-sectional area increase
- percent of the IIx fibres decreased & percent of type IIa increased

Question 26

Lecture 10:

What does resistance training increase?

Answer 26

Increases protein synthesis

Question 27

Lecture 10:

When discussing resistance training & diet, how much protein should be consumed & when?

Answer 27

• consume 1.6-1.7g of protein per kg of body weight per day to increase muscle mass
• consume 20-25g protein after resistance exercise for increased muscle growth (as protein synthesis greatest after exercise)

Question 28

Lecture 10:

What is protein synthesis with resistance training controlled by?

Answer 28

Controlled by mTOR (mechanistic target of rapamycin) - integrates input from insulin, GF, & amino acids while dictating the transcription of mRNA

Question 29

Lecture 10:

What occurs in the absence of mTOR in terms of protein synthesis?

Answer 29

Absence of mTOR means no protein synthesis can occur, no matter what you eat or exercise type

Question 30

Lecture 10:

Resistance training for children and adolescents - myth vs truth?

Answer 30

Myth = resistance training is unsafe due to growth & hormonal changes
Truth = it is safe with proper safety guards - children can gain both strength & muscle mass

Question 31

Lecture 10:

What are 3 benefits of resistance training for the elderly population?

Answer 31

Helps restore age-related loss of muscle, improves quality of life and health, & helps prevent falls

Question 32

Lecture 10:

What is strength increase dependant on in elderly?

Answer 32

Increases in strength is primarily dependent on neural adaptations (no diff across sex/race)