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HES 105 > Week 5 > Flashcards

Week 5 Flashcards

1
Q

What does contraction lead to?

A

Muscle tension

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2
Q

Define muscle tension

A

The Force generated by contracting muscle

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3
Q

Define load

A

The external force exerted on the muscle

Can be influenced by:
- external load + gravity
- body weight + gravity
- another muscle

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4
Q

What happens when tension is greater than the load?

A

There will be a concentric contraction and the muscle length will shorten

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5
Q

What happens when tension is less than load?

A

There will be an eccentric contraction and muscle length will lengthen

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6
Q

What happens when tension is equal to load?

A

There will be an isovolumetric contraction and muscle length will stay the same

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7
Q

What is a dynamic contraction and what are its two subcategories?

A

A dynamic contraction is one that moves the skeleton

two subcategories:
1. Isotonic: tension stays the same throughout contraction (velocity changes)
2. Isokinetic: velocity stays the same throughout contraction (tension changes)

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8
Q

What is a static contraction?

A

A contraction where no movement occurs - isometric

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9
Q

What results from more crossbridges?

A

More tension

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10
Q

What does max tension differ between?

A
  • movements due to mechanical factors
  • muscles due to morphological factors
  • contractions due to neural factors
  • physiological contexts (nutritional status, fatigue, etc…)
  • people
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11
Q

What are 3 mechanical factors that influence muscle tension

A
  1. Contraction velocity
  2. Muscle action
  3. Joint angle
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12
Q

Draw and explain the contraction velocity graph on page 4 of muscle tension I

A
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13
Q

In terms of strength, what is strongest for muscle contractions

A

Eccentric > isometric > concentric

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14
Q

How does joint angle affect tension?

A

Joint position (aka joint angle) influences muscle length

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15
Q

What else influences the relationship between force and angle other than muscle length?

A
  • other biomechanical factors
    • type of joint/level
    • location of muscle insertion
    • length of limb segments
  • morphological factors
    • xc area, pennation angle
  • individual factors
    • age, sex, training status
  • fatigue
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16
Q

What are the strongest contractions usually?

A
  • mechanically optimal
  • morphologically optimal
  • neurally optimal
  • metabolically optimal
  • psychologically optimal
  • in a body that is not experiencing fatigue
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17
Q

What is fatigue?

A

The inability to maintain a power output or force during any type of repeated or sustained muscle contractions

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18
Q

Why is understanding mechanisms of fatigue important?

A
  • to prevent/delay it in critical situations
  • to improve fatigue resistance through training
  • to optimize recovery in critical situations
  • to improve recovery rate/process through training
19
Q

What are the peripheral factors of fatigue (mainly local effects)

A
  • phosphagen depletion
  • substrate depletion
  • metabolite accumulation/ion imbalance
20
Q

What are the central factors of fatigue (global effects)

A
  • psychological factors
  • central and peripheral neural factors
  • oxygen supply
21
Q

Describe depletion of phosphagens in terms of fatigue

A

THE PRIMARY FATIGUE MECHANISM FOR PHOSPHAGEN SYSTEM

ATP and PCr deplete during very high intensity activity
- ATP can deplete to 40% of resting values
- PCr can deplete to 15% of resting values

To recover, ATP and PCr must be replenished

For half time, this takes ~20-25 seconds and for full time this takes 3-5 minutes

22
Q

Describe the accumulation of metabolites/ion imbalance in terms of fatigue

A

PRIMARY FATIGUE MECHANISM FOR ANAEROBIC LACTIC SYSTEM

Many metabolites/ions can interfere with ATP synthesis and/or muscle contraction when their quantities are too high/too low
Ex: H+, Ca2+, Ammonia/ammonium, Na+/K+, Pi

In order to recover, the body needs to reset

For half time, recovery takes ~5-8 mins and for full time, recovery takes 12-20 mins

23
Q

Describe substrate depletion (glycogen) in terms of fatigue

A

PRIMARY FATIGUE MECHANISM FOR AEROBIC SYSTEM

  • reduces rate of glycolysis which leads to reduced pyruvate available for CAC which means reduced ATP resynthesis
    • fat is probably available but fat burns in a CHO flame - can’t make oxaloacetate without burning CHO
  • reduces ability to maintain blood glucose concentration
    • can lead to CNS impairment/loss of coordination
    • bonking or hitting the wall

In order to recover, the muscle glycogen must be replaced

For half time, recovery takes ~5-6 hours w/ proper nutrition and for full time, recovery takes 1-2 days

24
Q

Describe neural fatigue in terms of central AND peripheral

A

POSSIBLE FATIGUE MECHANISM FOR ANY/ALL SYSTEMS

Central:
- occurs in brain and spinal cord
- loss of motivation and/or concentration
- reduced motor drive
- pain intolerance

Peripheral:
- occurs at neuromuscular junction
- decreased muscle excitability

25
Q

what are 3 morphological factors that influence muscle tension?

A
  1. cross-sectional area
  2. pennation angle
  3. muscle fiber type
26
Q

what does endurance mean

A

the ability to sustain/repeat contractions

27
Q

what relationship will there always be between force/power and duration/endurance

A

there will always be an inverse relationship

28
Q

what is max tension directly proportional to

A

muscle cross-sectional area (CSA)

29
Q

at the level of the muscle fiber, what does bigger muscle fibers mean?

A
  • more myofibrils
  • more myofilaments (actin + myosin)
  • more possible cross-bridges
30
Q

at the level of the muscle, what does bigger muscles mean

A

could mean bigger muscle fibers and/or MORE muscle fibers (+ more connective tissue)
- more actin + myosin
- more possible cross-bridges

31
Q

what does physiological cross-sectional area depend on?

A

the arrangement of fibers

  • fascicles are arranged differently in different muscles
  • in pennate muscle, fascicles attach obliquely to tendon
  • direction of tension is oblique to tendon

increased pennation angle means more fibers pulling in the direction of tension which means more potential cross-bridges

  • there is a tradeoff with shortening potential / velocity
32
Q

what can muscle fiber types be categorized according to?

A

contractile properties
- slow twitch (type I)
- fast twitch (type II)

metabolic properties
- oxidative (aerobic)
- oxidative/glycolytic (both)
- glycolytic (anaerobic)

33
Q

what are fibers typed via

A
  1. muscle biopsy
  2. staining
34
Q

complete the tables on page 6 of muscle tension II

A
35
Q

complete the table on page 8 of muscle tension II

A
36
Q

can we make muscles stronger? if so how?

A

Yes we can make muscles stronger

  • strength gains related to dose of training
    • increased gains over time
    • increased gains with increased time under tension
    • increased gains with increased intensity (increased load)
  • gains of 25-100% are common
  • gains evident at:
    • whole muscle level
    • single fiber level

gains are specific to muscle groups that are trained

37
Q

can we make muscles bigger?

A

Yes we can make muscles bigger

  • muscle CAS increases 7-15% within 10-14 weeks
  • training leads to hypertrophy
38
Q

what does fiber hypertrophy include?

A
  • increased size and number of myofibrils
  • increased contractile protein (more XBs = more tension)
  • increased connective tissue
39
Q

what is hypertrophy specific to?

A

muscle fiber types that are trained

40
Q

can we increase pennation angle?

A

yes we can

adaptations are specific to muscles that are trained

41
Q

can we convert fiber types into the type we want?

A

no we cant

fiber type distribution is genetically-determined and varies from muscle to muscle (highest % SO in postural muscles)

we cant turn slow-twitch fibers into fast-twitch fibers or vice versa

we CAN make FG better at oxidative metabolism
- FOG -> FG

42
Q

complete the table on page 11 of muscle tension II

A
43
Q

complete table on page 12 of muscle tension II

A

HES 105 (16 decks)

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