Week 9: Neuromuscular Adaptations to Exercise and Training Flashcards Preview

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Flashcards in Week 9: Neuromuscular Adaptations to Exercise and Training Deck (19)
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1
Q

What are some of the physiological adaptations to resistance training?

A

Muscle fibres: Increase in number, size, and strength and become more specific

Capillary density: Doesn’t change in both bodybuilders or powerlifters.

Mitochondria volume and density both decrease

Twitch contraction time: decreases

Enzymes: creatine phosphokinase increase

Glycolytic enzymes: PFK increases and LDH is unchanged

Aerobic metabolism enzymes: increases in CHO and unknown for triglyceride

Basal metabolism increases

Intramuscular fuel store: increases in ATP, PCr, Glycogen, and unknown for triglyceride

VO2 max decreases with circuits and heavy resistance.

Connective tissue ligament and tendon strength increases and no change in collagen content observed.

Body composition: Decrease
%fat and increase in free fat mass

Bone: Increase in mineral content and density but no change in CSA

2
Q

How does age affect muscle hypertrophy response?

A

There are less muscle hypertrophy response seen in elders and children. They rely more on the neural and other adaptations.

3
Q

How does age affect muscle hypertrophy response?

A

There are less muscle hypertrophy response seen in elders and children. They rely more on the neural and other adaptations.

4
Q

What is the relationship of hypertrophy in time? What would be observed in the first few training session regarding neural and muscular factors?

A

Hypertrophy benefits aren’t apparent for the first few training sessions but the adaptations are already seeing progress.

5
Q

What is said according to the size principle of MU recruitment?

A

MU’s recruited according to their threshold of activation.

Possible that some high threshold MU’s cant be recruited in an unfamiliar task but training may result in increased activation hence increased MU recruitment and force

6
Q

What is said according to the size principle of MU recruitment?

A

MU’s recruited according to their threshold of activation.

Possible that some high threshold MU’s cant be recruited in an unfamiliar task but training may result in increased activation hence increased MU recruitment and force

7
Q

What may be beneficial about increased neural firing frequency for the muscle?

A

Higher threshold MU’s could be recruited more generating greater force

8
Q

What are other neural factors that can contribute to muscle strength?

A
  • Increased efficiency of MU recruitment - preferential recruitment of larger fast-twitch fibres.
  • Increased efficiency of agonist activation - preferential recruitment of some muscles within a muscle group over others
  • decreased co-activation of antagonists (Need more research over this) - Strength athletes generally show decreased agonist-antagonist co-activation.
  • Decreased neural inhibition - Possible strength training may increase the ability to oppose autogenic inhibition (eg. GTO)
  • Changes in NMJ activity - increase SA at synapse or increase dispersion of synapses leading to enhanced E-C coupling.
9
Q

What is the definition of hypertrophy?

A

Increase in cell size. Not the muscle fibres that increases but the myofibril size and quantity increase

10
Q

What are the possible mechanisms for hypertrophy?

A

Increased myofibrils, increased actin and myosin filaments, Increased Sarcoplasm, Increased connective tissue.

11
Q

What may be the mechanism behind increases of myofibril numbers?

A

Thought to undergo longitudinal splitting into 2 or more daughter myofibrils. Increased sarcomere number in series. But length ususally changes during sport.

12
Q

What is the difference of paracrine and endocrine signaling and how does exercise stimulate muscle growth in response to both endocrine or paracrine.

A

Endocrine: hormones traveling through the blood stream

Paracrine: Hormones traveling locally

When someone injures one leg and is immobilise but is able to train with the other leg, the trained leg would most likely experience muscle hypertrophy. If the endocrine hormones are the only ones working this wouldnt make sense as the untrained legs would also retrieve benefits. Therefore its explained that it must be both endocrine and paracrine signaling that elads to this result

13
Q

What are the mechanisms of cell remodeling? Is it possible to convert fiber-types to another?

A

Mechanical stress may stimulate various extracellular signaling molecules, which may then stimulate previously dormant satellite cells to proliferate and differentiate.

Fusion of the new nuclei and incorporation into existing fibres probably enables formation of additional myofibrils.

Depending on training, type 2a muscle cells could develop anaerobic properties and vice versa

14
Q

What is hyperplasia? What are the current evidence behind it?

A

Hyperplasia is when there is an increas in the number of muscle cell/fibres.
When hyperplasia is observed in animals, ther seems to be no hypertrophy response.
There is evidence in animals however, there is not much evidence in humans.

15
Q

What are the causes to an improved power output following highly specific training?

A

Neural adaptations: Generally thought to be due to rapid recruitment of MU’s and increased firing frequency (net result = increased RFD: Rate of force development)

Improved intramuscular coordination: relationship between excitatory and inhibitory mechanism for one muscle for a specific movement.

Improved intermuscular coordintation: ability of all muscles involved in a movement (agonist, synergists and antagonists) to cooperate wholly with respect of an aim of movement

16
Q

Increase in MU firing frequency may increase force up to a certain frequency, however, what happens when that frequency is reached?

A

Force may not further increase however it may produce a faster RFD (how fast the force development reaches 100%)

17
Q

What are the 4 principles of training?

A

Specificity, Overload (intensity, frequency, duration), reversibility, and individual differences (most important)

18
Q

Explain Progressive resistance exercise

A

Progressively increase training resistance as the program progresses (overload).

There are no one-size-fits-all model for strength training but general points that may be important are:
* High volume/moderate intensity for hypertrophy. (How close we go to close to failure.

  • Low volume/high intensity for strength
  • Low volume/moderate/high intensity (speed) for power
  • Once a week with 1 RM can increase strength from 1-6 weeks (mostly for untrained)
  • Multi-set sessions best for increasing strength but single-set sessions can be of health and fitness benefits
19
Q

What are some practical recommendations for initiating resistance program?

A
  • Avoid maximal lifting initially
  • Use more reps with less resistance
  • After a week or two reduce rep no.
  • Progressively add weight as reach target no. of reps
  • Progress from larger to smaller muscle groups
  • Allow sufficient recovery