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Exercise Physiology > Week 3: Physiology of Strength & Power Training > Flashcards

Week 3: Physiology of Strength & Power Training Flashcards

1
Q

In dynamic concentric exercises:

Muscle length….
Function….
Context…

A

Decreases
Acceleration
Muscle active, contractile force greater than resistive force

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2
Q

In dynamic eccentric exercises:

Muscle length….
Function….
Context…

A

Increases
Deceleration
Muscle active, contractile force less than resistive force

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3
Q

In static isometric exercises:

Muscle length….
Function….
Context…

A

No change
Stabilisation
Muscle active, contractile force equal to resistive force

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4
Q

Resistance types…

What is an isotonic load?

What is a isokinetic load?

What is plyometric?

What is speed?

What is PNF

A

Isotonic load: constant resistance load but contractile force required varies by joint angle and muscle length eg dumbbell curl or bench press (differences in joint angle change the amount of force required). Variable resistance load to maintain contractile force required throughout range of motion. Eccentric load focusing on contraction during muscle-lengthening phase of exercise.

Isokinetic load: Mechanically braked loading at fixed speed to target/measure specific joint velocities

Plyometric: Focus on force development after sudden eccentric loading using elastic properties of muscles/tendons

Speed: Focus on overcoming resistance as quickly as possible

Proprioceptive neuromuscular facilitation (PNF): Focus on muscular inhibition/relaxation through isometric/concentric loading followed by passive stretching.

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5
Q

What is power?

A

Power = Work/Time
= Force x Distance/Time
= Force x velocity

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6
Q

What is rate of force development? How is it calculated?

A

An index of explosive strength

Calculated as the change in force per change in time ie RFD = change in force/change in time.

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7
Q

On a force/time curve, the steepest part indicates…

A

Peak RFD

The steeper the curve, the more explosive the athlete/action.

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8
Q

True or False - In sport, rate of force development is often more desirable than maximal force production

A

True

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9
Q

Force-velocity relationship

Less time for actin-myosin cross bridge cycles results in …. contractile force

Greater forces are produced in …. and …. muscle actions

Power can be targeted or RFD close to where the ….. occurs at the intersection with ……

A

Lower contractile force

Eccentric & isometric

Optimal velocity, maximal power output

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10
Q

Neural activation

  • Muscle contractile strength depends on the …., …. and …. of neural activation
  • When a motor unit fires, …. the muscle fibres it innervates are activated
  • Neural component measured using ….. (iEMG)
  • Greater electrical activity indicates …. motor unit recruitment or ….. motor unit firing rate
A
  • Muscle contractile strength depends on the frequency, magnitude and duration of neural activation
  • When a motor unit fires, all the muscle fibres it innervates are activated
  • Neural component measured using electromyograph (iEMG)
  • Greater electrical activity indicates greater motor unit recruitment or increased motor unit firing rate
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11
Q

Motor unit coordination

*Improved MU …. : ability to activate …. number and …. motor units
* Improved MU …..: ability to activate …. motor units … and with minimal latency
* Improved MU … ….: increased …. rate of motor units (discharge rate)

All contribute to increased ….. and …..

A
  1. recruitment, greater, size
  2. synchronisation, multiple, simultaneously
  3. rate coding, firing
  4. maximal force production, rate of force development
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12
Q

Integrated EMG analysis show that eccentric loading results in around ….. greater neural activity

A

7x - develop more force using eccentric training but there are trade-offs with muscle damage and soreness which need to be considered.

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13
Q

Neural disinhibition (preventing the inhibition of muscle contraction)

With long term training we have improvements in our proprioceptive responses to muscle tension. These include:

A

Muscle spindles: improved sensitivity to muscle fibre stretch deformation, signalling for activation of motor neuron – results in better control of the degree of muscle activation required to overcome resistance.

Golgi tendon organs: Improved ability of motor cortex to override GTO reflexive inhibition of muscle tension – allows muscle to produce greater contractile force

These contribute to increased force production and greater control of contractile force.

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14
Q

Intermuscular coordination components?

These contribute to…..

A

Synergist coactivation -

Antagonist co-contraction

Cross education

These contribute to improved contraction effectiveness, joint stability, bilateral muscular strength balance and overall force production

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15
Q

What is synergist co-activation

A

improved ability to activate synergist muscles that contribute to joint stability – particularly relevant in ballistic contractions (eg plyometrics, sprinting)

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16
Q

What is antagonist co-contraction?

A

ability to coordinate or reduce activation of antagonist muscles resulting in increased force production with same MU recruitment, improved movement control

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17
Q

What is cross education?

A

Performing unilateral exercise results in increased strength in contralateral muscle, suggesting a central neural adaptation account for a lot of strength improvement.

18
Q

Significance of adaptations to strength/power training

Increased IEMG activity

A

Increased maximal force production, RFD

19
Q

Significance of adaptations to strength/power training

Increased rate of MU activation

A

Increased RFD

20
Q

Significance of adaptations to strength/power training

Increased MU synchronisation

A

Increased RFD and ability to activate high

21
Q

Significance of adaptations to strength/power training

Increased duration high threshold MU activation

A
22
Q

Significance of adaptations to strength/power training

Increased stretch reflex sensitivity facilitating contraction

A

Increased RFD by assisting elastic components

23
Q

Significance of adaptations to strength/power training

Decreased activity of golgi tendon organs

A

Decreased inhibition of maximal muscle contraction

24
Q

Significance of adaptations to strength/power training

Increased coordination of antagonist muscle groups

A

Increased maximal force production and contraction effectiveness

25
Q

Significance of adaptations to strength/power training

Increased contralateral cross training

A

Increased strength balance between left and right side of body

26
Q
  • The majority of early strength gains during a training program are the result of …. adaptations
  • Eventually, myogenic factors begin to contribute to strength development with ….. becoming evident from ~….
  • Continued overload can lead to further improvements in strength from neural and muscular adaptations, however total hypertrophy achievable is limited by …..
A

Neural

Muscle protein accretion, ~6 wks onwards

Genetic factors (myosin)

27
Q

What is myoplasticity? Is remodelling specific to imposed muscle stimuli? What happens to muscle with reduced use?

A

Muscle is a highly responsive and adaptive tissue

Remodelling is specific to imposed muscle stimuli

It down regulates

28
Q

What is hypertrophy? Transient vs chronic

A

Transient: pumping up of muscle during single exercise bout due to fluid accumulation from blood plasma in interstitial space of muscle

Chronic: increase in muscle size after long-term resistance training due to changes in fibre size

29
Q

Fibre type changes

  • Hypertrophy greater in ….. MHC IIa fibres
  • IIa fibres determine maximal force capacity
  • Fibre type hypertrophy determined by training intensity – different metabolic stress results in …..
  • Resistance training causes acute release of …. …. …. ….
A

Fast twitch
Fibre type specific hypertrophy
MHC IIx mRNA isoforms

30
Q

Metabolic signals

  • ….. …… mediates the exercise-induced skeletal muscle response to resistance (and endurance) training
  • Resistance training induces increased activity in the …… signalling cascade
    This modules …… …… ….., leading to muscle hypertrophy
  • ….., ….. …. play important roles in promoting muscle growth
  • Important to note that increased ….. during endurance training signals …. which inhibits/promotes …. activation. This results in …. muscle protein synthesis
A

Intracellular signalling

PI3-k-Akt-mTOR, muscle protein synthesis rate

Testosterone, IGF-1 and GH

AMPK, TSC 1/2, inhibits MTOR, reduced

31
Q

Protein synthesis

Feeding and resistance training can modulate MPS and MPB balance

  • MPS>MPB = anabolic state
  • MPB>MPS = catabolic state

Chronic positive net protein balance results in hypertrophy

A

anabolic state
catabolic state

Chronic positive net protein balance results in hypertrophy

32
Q

Contractile components

  • The ….. properties of muscle tissue allow it to be ….; absorbing force and enhancing force development
  • Divided into …. (SEC) and …. elastic components (PEC)
  • Relevant in stretch shortening cycle (SSC) where …. energy is stored in …., ….. (PE) converted to ….. energy (KE) and elastic recoil aids force development
  • Elastic components are …., particularly with …. and … exercise
  • SSC ….. with fatigue
A

Viscoelastic, stretched
Series, parallel
Elastic, SEC,
Potential energy, kinetic energy
Trainable - power & plyometric
Decreased

33
Q

Other structural adaptations to resistance training and their significance

Increased muscle fibre size (CSA)

A

Increased muscle contractile capacity

34
Q

Other structural adaptations to resistance training and their significance

Increased Myosin heavy chain (MHC) IIa isoforms

A

Decreased myosin cycling rate

35
Q

Other structural adaptations to resistance training and their significance

Increased pennation angle

A

Increased force production capabilities

36
Q

Other structural adaptations to resistance training and their significance

Increased type I and II fibre area

A

Increased strength, reflecting selective recruitment

37
Q

Metabolic adaptations to strength & power training

A

Enzyme activity
Metabolism
Substrate storage
Cardiovascular

38
Q

Metabolic adaptations & their significance

A

increased fat free mass (increased resting metabolic rate)

Increased PCr, PFK, myokinase content (increased anaerobic work capacity)

Increased ATPase activity (Increased dephosphorlyation rate of ATP for energy)

Increased insulin sensitvity (increased blood glucose control)

Increased intramuscular glycogen storage (increased availability for glycolysis, energy)

Decreased capillary density (increased diffusion distance, anaerobic demand)

Decreased mitochondrial density (decreased relative oxidative metabolic capacity)

39
Q

Muscle damage and soreness (metabolic)

  • Acute soreness:
  • ….. accumulation
  • Tissue ….. (swelling)
  • Delayed onset muscle soreness (DOMS)
  • Structural ….. to ….. (tendons, fascia) and ….
  • Nerve endings stimulated by potassium/histamine
  • Muscle spasm due to decreased …..
  • Onset within …. hours of exercise and can last …. days
A

H+, oedema
Microdamage, connective tissue, cell membrane
02
24hrs, several

40
Q

Potential mechanism for DOMS

A

Damage to the muscle due to high tension, particularly during eccentric, intense or prolonged exercise

Injury tends to tissue oedema and inflammation eg increased neutrophils, leukocytes, monocytes, cytokines)

Increased cell tension and strain from oedema and agents, such as prostaglandins and histamine cause pain

Additional muscle tissue breakdown and pain occur due to formation of proteases, phospholipases, and reactive oxygen species.

Cells repair themselves an form protective proteins that prevent muscle soreness during subsequent workouts.

41
Q

Preventing/Reducing DOMS

A
  • Minimise eccentric work early in training program
  • Progressively build volume and intensity
  • Warming up, cooling down, and stretching does not prevent soreness
  • Suffer early and adapt repeated bout effect
42
Q

Responses to resistance training

A
  • Adaptations to resistance training are specific to the stimulus
  • We can modify the stimulus through load, contraction type, velocity, joint angle, movement pattern
  • We can use force-velocity and force-time curves to assess current capabilities and target specific performance improvements
  • Adaptations can be neural, myogenic or metabolic
  • Early improvements in strength are neural

Exercise Physiology (12 decks)

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