Week 9 - Physiology of Resistance Training

Question 1

Define maximal strength

Answer 1

Maximal force that a muscle group can generate. E.g 1 rep max

Question 2

Define muscular endurance

Answer 2

Ability to make repeated contractions against submaximal load

Question 3

What is high resistance strength training

Answer 3

Results in strength increase approx 6 to 10 reps till fatigue

Question 4

What is low-resistance training

Answer 4

Results in increases in endurance approx 35 to 40 reps to fatigue

Question 5

Whats the effects of ageing on both muscle mass and strength

Answer 5

loss of muscle mass (termed sarcopenia)
Atrophy of type two fibers
Reduced number of both type one and two fibers loss
Resistance training promotes hypertrophy/strength gains in older individuals but lower than young individuals

Question 6

What are the neural adaptations responsible for early gain in strength

Answer 6

Muscular strength increases in first two weeks of training without increase in muscle fiber size
Phenomenon of cross education training of one limb results in increases of strength in untrained limb

Question 7

What are the adaptations of muscle fibers in increasing muscle strength

Answer 7

Increased muscle fibre specific tension
Increased muscle mass

Question 8

What are the adaptations to neural steps resulting in muscular contraction

Answer 8

Increased neural drive
Increased number motor units received
Increased firing rate of motor units
Increased motor unit synchronization
Improved neural transmission across neuromuscular junction

Question 9

What are the adaptations within muscle fibres to resistance training

Answer 9

Increased muscle fibre specific tension in type 1 fibres
Training induced increases in muscle mass - hyperplasia is increased number of fibres, hypertrophy is increased cross-sectional area of muscle fibres

Question 10

How does resistance training effect muscle protein synthesis

Answer 10

A single bout of resistance exercise promotes increase in both muscle protein synthesis and breakdown
Muscle growth occurs because protein synthesis exceeds rate of breakdown

Question 11

How is the time course of increased muscle synthesis impacted by resistance training

Answer 11

Increases 50 to 150% with 1-4 hours post exercise
Elevated 30 to 48hours depending on training status

Question 12

What are the key factors leading to resistance training induced increass in muscle protein synthesis

Answer 12

mRNA increases resulting in protein synthesis at the ribosome
Ribosomes increase in number and elebvate muscle’s protein synthesis activity
Activation of protein kinase accelearates protein synthesis following a bout of resistance training

Question 13

Whats the effect of Phosphaditic acid (PA) and Ras homolog enriched in brain (rheb)on mTOR activation

Answer 13

Muscle contractions activate sarcolemmal mechanoreceptor stimulating synthesis of PA
Contraction-induced activation of sarcolemmal mechanoreceptors also acitvate extra cellular signal-regulated kinase (Erk), active erk inhibits TSC2 which inhibits rheb resulting in mTOR activation by synthesis of PA and removing the TSC2 inhibition of Rheb

Question 14

What are Other factors linked to resistance training-induced hypertrophy

Answer 14

Both insulin-like growth factor-1 (IGF-1) and growth hormone are linked to mTOR
activation and have potential to increase muscle protein synthesis.
Many individuals use over-the-counter nonsteroidal anti-inflammatory drugs (for
example, ibuprofen and acetaminophen) to combat sore muscles and arthritis.

Question 15

What are satelite cells

Answer 15

Stem cells that are located between the sarcolemma and basal lamina

Question 16

How do satelite cells impact resistance training

Answer 16

Resistance training activates satellite cells to divide and fuse with adjacent muscle fibers to increase myonuclei

Question 17

Whats the effect of myonuceli and resistance training

Answer 17

Resistance training-induced increases in
myonuclei results in a constant ratio between
number of myonuclei and size of muscle fiber
addition of new myonuclei to fibers is likely required to support increased protein synthesis in
larger muscle fibers

Question 18

How does age effect satelite cells and resistance training

Answer 18

Resistance training-induced satellite cell
activation is blunted in older individuals

Question 19

What effect do genetics have on muscle mass

Answer 19

Approximately 80% of the differences in muscle mass
between individuals is due to genetic variation
These are due to variations between people in their ability to activate protein synthesis genes in
skeletal muscle in response to resistance training

Question 20

What happens as a result of detraining in relation to strength training

Answer 20

Cessation of resistance training results in muscle atrophy
and a loss of strength.
However the rate of detraining is slower compared to resistance training

Question 21

How quickly can strength loss gains be regained after detraining

Answer 21

Recovery of dynamic strength loss can occur rapidly
(within 6 weeks) with retraining.
Argued that this is due to muscle memory as resistance training-induced increases in myonuclei in the
trained fibers that are not lost during detraining

Question 22

What is the result of prolonged muscle inactivity

Answer 22

0 to 30 days of muscle inactivity can result in 20 to 30% reduction in muscle fiber size (muscle atrophy)

Question 23

How can muscle mass be conserved

Answer 23

dependent upon balance between protein synthesis and rates of
protein degradation.

Question 24

What is the key mechanism responsible for inactivity induced muscle atrophy

Answer 24

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

Question 25

What can result in interference of muscle adaptations

Answer 25

Strength training increases muscle fiber size whereas
endurance training does not
Depends on intensity, volume, and frequency of endurance
training.

Question 26

What are potential mechanisms for concurrent exercise

Answer 26

Neural factors - impaired motor unit recruitment but there is limited evidence supporting this
Overtraining but no concrete evidence either
Depressed protein synthesis - endurance training cell signaling can interfere with protein synthesis via inhibition of mTOR by activating AMPK