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Exercise Physiology > Acute Exercise Responses > Flashcards

Acute Exercise Responses Flashcards

1
Q

What is the definition of onset of exercise?

A

the beginning or first 30 seconds

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2
Q

what two factors will dictate which fibers and how many are recruited in acute exercise?

A

intensity and mode

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3
Q

what happens to metabolism at the onset of exercise at all modes and intensitites?

A

a spike in the immediate system

  • muscular contractions ramp up glycogenolysis and glycolysis for ATP replenishment (increased glycolytic activity from immediate system)
  • O2 stored on myoglobin is used until HR and ventilation increase and establish an adequate O2 supply.
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4
Q

what happens to the cardiovascular system due to increased metabolic demands at onset of exercise?

A

PSNS inhibited
SNS releases Norepinephrine
-increases HR and SV
-vasoconstriction to shunt blood to active muscles and skin
(feed forward from hypothalamus and feedback from exercise pressor reflex)

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5
Q

What happens to the respiratory system during increased metabolic demands of exercise at onset?

A

PSNS inhibited
SNS releases EPI and NOREPI to dilate bronchioles
-vasoconstriction for blood flow to ventilatory and skeletal muscles
VE will increase initially due to an enlarge VT (tidal volume)

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6
Q

How does the intesitiy of exercise determine how VE increases?

A

low to moderate- increases are proportional to effort

high intensities- increases are disproportionately large (VE is very large)

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7
Q

Which exercise would tax each system the most at the onset of exercise?

A

?

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8
Q

During Exercise, what neuromuscular functions are dictated by intensity and mode?

A

which fibers are recruited

how many are recruited

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9
Q

During Ex. what happens if a working muscle fatigues?

A

additional fibers are recruited to maintain force output. if all of the working type are fatigued, then replacement fibers are recruited. first by the same type, then usually higher order if they are available.
If all 2x are used at fatigued, move to 2a, but intensity would decrease

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10
Q

what dictates which energy system predominates to replenish ATP utilized for muscular contraction during exercise?

A

Intensity of exercise.

all 3 are always on, but intensity says which one is dominant

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11
Q

what are the O2 demands based on intensity during ex.

A

regardless of intensity, it is unregulated to some extent.
once the O2 stored on myoglobin is used up, more is needed
-low-intesity = high O2 demand
-short-duriation or high intensity = less O2 during. (but EPOC after)

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12
Q

how is glycogen regulated during ex?

A

constantly being formed form glucose via glycogenisis to provide a steady supply of glucose or G6p for glycolysis
-extended exercise(hours): levels may be depleted that intensity is compromised. –> new glucose is created from fatty acids and AA via gluconeogenisis ( only happens at LOW intensities)

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13
Q

what happens in metabolism at higher ex. intensities to pyruvate?

A

cannot be converted to acetyl coA and shuttled to mitochondria –> concerted to lactate.

  • once passed lactate threshold, H+ accumulates within muscles
  • H+ and lactate diffuses into muscle capillaries and transported to blood
  • -goes to liver to be turned into glucose or pyruvate or oxidized to CO2 and H2O to produce ATP
  • -or goes to other muscles/tissues to be utilized as a fuel source
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14
Q

During exercise, how does the cardiovascular system maintain cardiac output (Q)

A

SNS and PSNS balance one another

-baro/chemorecrptor feedback, metabolite buildup and stress on vessel walls.

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15
Q

How does the heart itself influence the cardiovascular system during exercise?

A

myocardial O2 consumption increases because of Q increase

  • mostly because of HR increase
  • RPP- Hr*SBP
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16
Q

How is CV drift influenced during exercise?

A

-prolonged exercise- SV and MAP decrease (fluid loss from sweating) –> heart rate increase

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17
Q

How does blood shunting help get blood to tissues that are in need of O2 and nutrients during exercise?

A
  • EDRFs (nitric oxide) induce vasodilation and override SNS vasoconsriction.
  • oxide suppliments cause vasodilation but it is less localized. (all over)
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18
Q

how does aerobic exercise cause CV difference during ex?

A

VOLUME LOAD. from increase pre load
increase in Q, HR, SV, EF, and SBP
no change in DBP
-big decrease in TPR b/c of local vasodilation and no increase in DBP (facilitates peripheral blood flow)

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19
Q

how does resistance training (traditional) effect CV during exercise?

A

PRESSURE LOAD OR HIGH AFTER LOAD

  • increase SBP, DBP, MAP
  • overall big decrease in TPR
20
Q

What are differnces in CV during ex. between supine and upright exercise?

A

upright: facilitated by the muscle pump (Sv decrease*Hr increase)
Supine- greater preload/venous return –> increase SV * decrease HR

21
Q

what are CV differences between arm and leg exercises at ABSOLUTE WORKLOADS?

A

arms have great CV response because they have smaller muscles & there is greater vasoconstriction of legs during arm workout that lead to:

  • increased HR, SBP, DBP, VO2, VE, RER & LA.
  • SV lower and Lactate threshold is reached sooner
    legs: more fatigue resistant. more muscle mass activated. higher work capacity of leg muscles.
22
Q

how does VE change during exercise?

A

increases:
low to mod- increase proportional to effort
high- disproportionately large (
incremental exercise: VE increase disproportionately at intestates greater than 50-60% VO2 max (LThreshold)
-b/c increased frequency to exhale more CO2 to buffer blood pH at lactate threshold.
-Ventililatory Threshold= point where increase in VE and VCO2 occurs disproportionately

23
Q

How does the Bohr effect influence Resp. during exercise?

A

increase in PCO2, 2,3 BPG, H+ by working muscles causes a Hb affinity decreases at tissue level to provide enough O2

24
Q

What limiting factors of ventilation happen during exercise?

A
  • maybe from O2 consumption by ventilatory muscles (up to 15% of Vo2 and Q)
  • at max aerobic: max expansion of pulmonary capillaries limits %SO2
  • reduces RBC transit time –> PaO2 decreases –> limits exercise performance.
25
Q

What happens to the neuromuscular system post-exericse?

A

it is not working since the muscles aren’t working anymore….

26
Q

Explain Excess Post-exercise Oxygen Consumption (EPOC).

A

post-exercise, mitochondrial respiration will ramp up to replenish ATP depleted from muscular contraction.
it depends on the intensity of the exercise (how much O2 consumption)
-an increased Q (cardiovascular response) delivers O2 and shuttles lactate and waste products away from muscles.
-increased Ve(Respiratory response) supplies O2 for EPOC and rids excess CO2.
-as energy stores are reached Q and Ve return to normal.

27
Q

Why is it important to eat shortly after a workout?

A

there is a 20-30 minute window post-exercise where glucose and glycogen synthesis increase to replenish glucose depleted during exercise.k

28
Q

where does lactate go post-exercise?

A

it is shuttled out of the muscles into the blood circulation and surrounding tissues.

29
Q

which types of exercise would tax each system the most after exercise?

A

high intensity exercises. not getting O2 in during anaerobic exercises, so would need a big EPOC after

30
Q

how could EPOC be used for weight loss

A

EPOC can last for 48 hours, it would increase your resting metabolism and increase your fat burning during mitochondrial respiration.

31
Q

Which hormones provide fuel (glucose) for exercise?

A

Insulin- technically decreases, but affinity/ efficiency increases so that glucose can get to the blood and uptake by the muscles.
Glucagon- increases a little with intensity, but a lot with duration. stimulates glycogenolysis to make G6P/glucose
Epinephrine- an immediate spike (fight or flight) then gradual increase with long duration or high intestines.

32
Q

what are the effects of norepinephrine?

A

usually same as epinephrine.

it is a hormone and neurotransmitter

33
Q

Explain why cortisol could be dangerous during exercise

A

cortisol causes a break down of amino acids, which could inhibit recovery after a workout.

34
Q

what hormones mitigate the negative response of cortisol?

A

Growth hormone and IGF-1.
Growth hormone increases which would increase IGF-1 (AA uptake and protein synthesis).
*they largely influence recovery and exercise adaptations. the goal is to try and maximize levels during and post-exercise.

35
Q

which hormones are secreted more at higher intensities?

A

growth hormone and IGF-1

epinephrine, norepinephrine. slightly glucagon

36
Q

what is fatigue?

A
  • a decline in max force output

- changes in NM recruitment to maintain muscle contraction/ work (changes is order and number or fibers)

37
Q

how does the site of fatigue change?

A

-IT IS dependent of the type of activity
-type 2 fibers fatigue faster than type 1. 2x faster than 2a
arms would fatigue faster than legs/ other places with more type 2 fibers

38
Q

what are the three mechanisms of fatigue?

A
  1. central fatigue
  2. peripheral fatigue
  3. Metabolic fatigue
39
Q

Explain the effects of central fatigue.

A

during of from previous exercise, central fatigue is caused by failure of the CNS to initiate signal to muscles by either:

  • muscle stress or damage –> afferent –> CNS –> inhibits muscles to decrease motor unit recruitment by decrease rate coding or decrease in activation of motor neurons
  • Elevation of FFA –> increase in tryptophan uptake in the brain which binds to albumin –> increases serotonin synthesis –> fatigue (sleepy)
40
Q

Explain the effects of peripheral fatigue that are not likely to happen in humans?

A
  1. failure of alpha-motor neurons to transmit signals –> not really the a-motor neuron…it is really the CNS reducing the signal to it.
  2. failure of the neuromuscular junction to relay signals by Ach depletion in type 2 fibers competing for binding sites. –> humans don’t have problems with ACH amount
41
Q

what is the most common sign of peripheral fatigue?

A

Failure of excitation-contraction coupling process:
-K+ efflux from muscles may impair Action Potentials –> cause a rapid stimuli of rate coding so that the membrane polarity doesn’t restore to normal.
NaK+ pumps can’t restore membrane potentials quickly enough during rapid stimuli from K+ efflux –> so action potentials can’t depolarize because the membrane balance is off.
*disruption of AP thru DHP, EDFP and anodyne receptors results in less Ca++ release.
this can result in muscle damage during endurance exercise

42
Q

What two hypothesis make up metabolic fatigue?

A

Exhaustion hypothesis- you fun out of fuel (ATP, CrP, glycogen)
Accumulation Hypothesis- LA increases, H+ release = increase in acidity = shuts down enzymes &:
-CA++–>troponin binding
-Ca++ release and uptake
-sarcolemma excitability
-various enzyme activity
-ATP hydrolysis and synthesis

43
Q

How does duration of fatigue relate to mechanisms of fatigue?

A

Peripheral fatigue- few seconds to few minutes (HFF)
metabolic fatigue- few minutes up to hours
central fatigue- several hours to days

44
Q

explain HFF (high frequency fatigue)

A

short duration/high intensity (sprints, lifting)
overstimulation of muscle fiber–> K+ efflux impairs depolarization
-depending on degree of damage, once NA-K pump restores gradient, muscle can work normally

45
Q

explain what happens when fatigue lasts a few minutes up to a few hours?

A

during extended duration exercise (marathon running) ATP-Crp quick restoration are not enough to increase the ability to exert force.

  • when you decrease glycogen stores –> use other fuel sources, but not for extended high intensity work,
  • in order to restore muscle function, glucose/glycogen levels must increase (eat carbohydrates during extended exercise efforts)
46
Q

Low frequency Fatigue (LFF) associated with central fatigue,

A

endurance exercise or high intensity that causes DOMS

  • initial decline in force production from excessive Ca++ exposure from excitation-contraction coupling process
  • decline in force production from myofilament damage
  • contractile failure sends feedback to CNS then inhibits a-motor neurons to prevent further muscle damage/work.
  • *can last weeks.

Exercise Physiology (7 decks)

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