Resistance/strength training

Question 1

Muscular strength

Answer 1

max force that a muscle group can generate
1 rep max

Question 2

Muscular endurance

Answer 2

ability to make repeated contractions against submax load

Question 3

Strength training

Answer 3

high-resistance (6-10 reps till fatigue) = strength increase
low-resistance (35-40 reps till fatigue) = increase endurance

Question 4

Ageing

Answer 4

loss of muscle mass (sarcopenia)
atrophy type 2 fibres
reduced number of both type 1 and 2 fibres (loss of motor neurons)
resistance training promotes hypertrophy/strength gains in older ind but lower than young

Question 5

Neural adaptations

Answer 5

early
strength gains during first 8 weeks of training due to nervous system
muscular strength increase first 2 weeks without increase in muscle fibre size
cross education - training of one limb results in increases strength in untrained limb

Question 6

Early gains

Answer 6

Increased neural drive (measured via EMG)

Increased number of motor units recruited

Increased firing rate of motor units

Increased motor unit synchronization

Improved neural transmission across neuromuscular junction

Increased size of NMJ and vesicles containingACh

Question 7

Hyperplasia

Answer 7

increased number of fibres

Question 8

Hypertrophy

Answer 8

increased cross-sectional area of muscle fibres
type II > type I
dominant factor in resistance training-induced increases in muscle mass
due to increased muscle proteins

Question 9

Muscle adaptations resistance training

Answer 9

increased muscle fibre specific tension in type I
increased calcium sensitivity = greater number crossbridges bound to actin
enables more actin-myosin cross-bridge formation = more force per motor unit

Question 10

Resistance training protein synthesis

Answer 10

increase protein synthesis and breakdown
muscle growth = protein synthesis > breakdown
slow rate - exceed for 3+ weeks for sig fibre growth

Question 11

Time course resistance training protein synthesis

Answer 11

increase 50-150% with 1-4h post exercise
elevated 30 to 48h depending on training status
muscle hypertrophy faster in untrained

Question 12

Factors contribute to muscle protein synthesis increase

Answer 12

mRNA increases = protein synthesis at ribosome
ribosome increase in number and elevate muscle proteins synthesis capacity
activation of protein kinase (mTOR) accelerate protein synthesis

Question 13

Signaling molecules stimulate mTOR activation

Answer 13

Phosphatidic acid (PA)
Ras homolog enriched in brain (Rheb)

Muscle contractions activate asarcolemmalmechanoreceptor stimulating synthesis of PA.

Contraction-induced activation ofsarcolemmalmechanoreceptors also activatesextracellular signal-regulated kinase (Erk)
-activeErkinhibits TSC2, which is an inhibitor ofRheb.

Hence, resistance training activates mTOR by synthesizing PA andremoving the TSC2 inhibition ofRheb

Question 14

Time course molecular response resistance training

Answer 14

seconds = increase Rheb and PA
minutes = increase mTOR activation
hours = increase protein synthesis

Question 15

Resistance training-induced hypertrophy

Answer 15

insulin-like growth factor-1 (IGF-1)
growth hormone
= linked to mTOR activation

single bout exercise = small increase in circulating levels

Question 16

Satellite cells

Answer 16

stem cells located between sarcolemma and basal lamina

resistance training = activate satellite cells to divide
fuse with adjacent muscle fibres to increase myonuclei
parallel increase - no. myonuclei : size muscle fibre

addition new myonuclei to fibres = required to support increase protein synthesis
increase myofibrillar proteins
myofibre CSA

Question 17

Genetic influence on hypertrophy

Answer 17

80% ind differbce due to genetic variation

47 diff genes major contributor to muscle mass
hypertrophy-linked genes linked to mTOR pathway - activated via resistance training
high vs low responders - ability to activate specific ‘protein synthesis’ genes in skeletal muscle

Question 18

Non-responder

Answer 18

low genetic potential for hypertrophy

Question 19

Moderate-responder

Answer 19

moderate genetic potential for hypertrophy

Question 20

High-responder

Answer 20

high genetic potential for hypertrophy

Question 21

Detraining strength training

Answer 21

muscle atrophy (20-30% in 20-30 days)
loss of strength
rate slower than endurance training
recovery rapid (6 weeks) - muscle memory - myonucleui in trained fibre not lost

Question 22

Muscle protein balance

Answer 22

conservation muscle mass dependent on balance protein synthesis and rates protein degradation

inactive muscle - decrease protein synthesis
increase protein degradation

active muscle - increase protein synthesis
decrease protein degradation

Question 23

Key mechanism muscle atrophy

Answer 23

increased radical production in muscle fibres (oxidative stress)
decreased protein synthesis
increased protein breakdown

Question 24

strength vs endurance training

Answer 24

strength training increase muscle fibre
together = impairs strength gains

neural factors - impaired motor unit recruitment
overtraining
depressed protein synthesis - endurance training cell signaling interfere with protein synthesis via inhibition of mTOR by activation of AMPK