The Physiology of Resistance/Strength Training Flashcards

1
Q

Define Muscular strength

A

Maximal force that a muscle group can generate (1-RM)

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2
Q

Define Muscular endurance

A

Ability to make repeated contractions against a submaximal load

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3
Q

Strength training - how many reps till fatigue in high-resistance and low-resistance training?

A

*High-resistance training (that is 6 to 10 reps till fatigue).
- Results in strength increases.
* Low-resistance training (that is 35 to 40 reps till fatigue).
- Results in increases in endurance

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4
Q

What does ageing result in?

A

A loss of muscle mass and strength
- loss of muscle mass (sarcopenia)
- atrophy type 2 fibres
- reduced number of both type 1 and 2 muscle fibres
- Resistance training promotes hypertrophy/strength gains in older individuals but lower than young individuals.

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5
Q

What is responsible for early gains in strength, and what is this evidenced by?

A

Neural adaptations - as evidenced by:
- muscular strength increases in first 2 weeks of training without increase in muscle fibre size
- phenomenon of “cross-education” - training of one limb results in increases of strength in UT limb

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6
Q

What adaptations within the muscle fibre occur later on…?

A
  • increased muscle fibre specific tension
  • increased muscle mass
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7
Q

What adaptations are included in the early gains related to changes in nervous system?

A
  • Increased Neural Drive (measured via EMG).
  • Increased number motor units recruited.
  • Increased firing rate of motor units.
  • Increased motor unit synchronization.
  • Improved neural transmission across neuromuscular junction.
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8
Q

What is the mechanism responsible for training-induced increase in specific tension in type 1 fibres?

A

Appears to be linked to increased calcium sensitivity - results in greater number of cross-bridges bound to actin

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9
Q

Define hyperplasia

A

Increased number of fibres

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10
Q

Define Hypertrophy

A

Increased CSA of muscle fibres
- likely dominant factor in resistance training-induced increases in muscle mass.
- due to actin and myosin
- evidence of resistance training-induced transition from type IIx to IIa (but not type II to type I)

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11
Q

Protein synthesis must exceed breakdown for ? weeks or more to achieve significant fibre growth

A

3 weeks or more

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12
Q

What are the key factors which contribute to resistance training-induced increases in MPS (signalling events)?

A
  • mRNA increases resulting in PS at ribosome
  • Ribosomes increase in number and elevate muscle’s PS capacity
  • Activation of the protein kinase mTOR is the KEY FACTOR ACCELERATING PROTEIN PS following bout of resistance training
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13
Q

What 2 signalling molecules stimulate mTOR activation?

A

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

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14
Q

Time course of molecular responses to resistance training - What are the post-exercise molecular responses ?

A

Secs - increased Rheb and PA
Mins - increased mTOR activation
Hours - increased PS

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15
Q

What other hormones are linked to mTOR activation

A

IGF-1 and GH

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16
Q

What effect does resistance training have on satellite cells?

A
  • RT activates satellite cells to divide and fuse with adjacent muscle fibres to increase myonuclei.
  • RT-induced increases in myonuclei results in a constant ratio between number of myonuclei and size of muscle fibre
  • Addition of new myonuclei to fibres is likely required to support increased PS in larger muscle fibres
17
Q

What effect does age have on RT induced satellite cell activation?

A

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

18
Q

Approx ?% of the differences in muscle mass between individuals is due to genetic variation?

A

80%

19
Q

Is the rate of strength loss faster or slower than in endurance training, following the cessation of exercise?

A

Slower

20
Q

Recovery of dynamic strength loss can occur rapidly (within ? weeks) with retraining.

A

6 weeks

21
Q

Muscle memory is the rapid recovery during retraining, after prolonged periods of inactivity. What is muscle memory due to?

A

resistance training-induced increases in myonuclei in the trained fibres that are not lost during detraining. Maintaining myonuclei provides advantage in rapid protein synthesis upon retraining

22
Q

20-30 days of muscle inactivity can results in ?% reduction in muscle fibre size.

A

20-30% reduction.
- Conservation of muscle mass is dependent upon balance between protein synthesis and rates of protein degradation

23
Q

What is the key mechanism responsible for inactivity-induced muscle atrophy?

A

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

24
Q

Studies conclude that concurrent strength & endurance training impairs strength gains compared to strength training alone. What are the potential mechanisms for this?

A

Neural factors (impaired MU recruitment)

Overtraining

Depressed PS (endurance training cell signalling can interfere with PS) - via inhibition of mTOR by AMPK activation.