Acute Exercise Responses Flashcards
(46 cards)
What is the definition of onset of exercise?
the beginning or first 30 seconds
what two factors will dictate which fibers and how many are recruited in acute exercise?
intensity and mode
what happens to metabolism at the onset of exercise at all modes and intensitites?
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.
what happens to the cardiovascular system due to increased metabolic demands at onset of exercise?
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)
What happens to the respiratory system during increased metabolic demands of exercise at onset?
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)
How does the intesitiy of exercise determine how VE increases?
low to moderate- increases are proportional to effort
high intensities- increases are disproportionately large (VE is very large)
Which exercise would tax each system the most at the onset of exercise?
?
During Exercise, what neuromuscular functions are dictated by intensity and mode?
which fibers are recruited
how many are recruited
During Ex. what happens if a working muscle fatigues?
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
what dictates which energy system predominates to replenish ATP utilized for muscular contraction during exercise?
Intensity of exercise.
all 3 are always on, but intensity says which one is dominant
what are the O2 demands based on intensity during ex.
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)
how is glycogen regulated during ex?
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)
what happens in metabolism at higher ex. intensities to pyruvate?
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
During exercise, how does the cardiovascular system maintain cardiac output (Q)
SNS and PSNS balance one another
-baro/chemorecrptor feedback, metabolite buildup and stress on vessel walls.
How does the heart itself influence the cardiovascular system during exercise?
myocardial O2 consumption increases because of Q increase
- mostly because of HR increase
- RPP- Hr*SBP
How is CV drift influenced during exercise?
-prolonged exercise- SV and MAP decrease (fluid loss from sweating) –> heart rate increase
How does blood shunting help get blood to tissues that are in need of O2 and nutrients during exercise?
- EDRFs (nitric oxide) induce vasodilation and override SNS vasoconsriction.
- oxide suppliments cause vasodilation but it is less localized. (all over)
how does aerobic exercise cause CV difference during ex?
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)
how does resistance training (traditional) effect CV during exercise?
PRESSURE LOAD OR HIGH AFTER LOAD
- increase SBP, DBP, MAP
- overall big decrease in TPR
What are differnces in CV during ex. between supine and upright exercise?
upright: facilitated by the muscle pump (Sv decrease*Hr increase)
Supine- greater preload/venous return –> increase SV * decrease HR
what are CV differences between arm and leg exercises at ABSOLUTE WORKLOADS?
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.
how does VE change during exercise?
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
How does the Bohr effect influence Resp. during exercise?
increase in PCO2, 2,3 BPG, H+ by working muscles causes a Hb affinity decreases at tissue level to provide enough O2
What limiting factors of ventilation happen during exercise?
- 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.
