Unit 4

endurance training

which type of training involves repetitive muscular contractions sustained over a prolonged period of time?

maximal O2 uptake, lactate threshold, and gross mechanical efficiency

what are the three primary physiological factors associated with success in endurance exercise performance?

VO2 = CO x a-vO2 diff

Which equation mathematically describes oxygen uptake (VO2​)?

50%

what proportion of an untrained individual's VO2​max is accounted for by genetic factors?

15-20%

What is the typical magnitude of VO2​max improvement expected in an average training responder?

50%

What is the typical magnitude of VO2​max improvement expected in a high training responder?

mitochondrial DNA (mtDNA)

Which non-nuclear cellular genome plays an important role in determining an individual's initial VO2​max and how well they respond to training?

O2

Endurance training improves ______ delivery and ______ extraction from the blood

gross mechanical efficiency

The O2 cost required to generate a given running speed or cycling power output

lactate threshold

the work rate or exercise intensity at which blood lactate concentration begins to accumulate rapidly

higher

does having a higher or lower LT threshold allow an athlete to sustain a higher exercise intensity before acid-base disturbances cause fatigue?

PGC-1 alpha

According to the muscle fiber signaling network, which coactivator acts as the central hub for endurance adaptation?

type I

what type of muscle fibers enhance mechanical efficiency?

slow

what type of myosin isoform enhance mechanical efficiency? (slow or fast)

a single bout

following ______ exercise specific mRNA content increases within minutes to hours post exercise (a single bout or repeated)

protein

regular bouts over weeks to months accumulate long-term increases in ________ content and performance

mRNAs

Different _____ peak at different post-exercise time points before returning to baseline within 24 hours

microRNA

small RNA molecules that decrease protein synthesis by binding to mRNA and blocking its translation

decrease

if there is an increase in microRNA levels, will there be an increase or decrease in protein synthesis?

miR-31

Which specific microRNA is downregulated by endurance training to allow increased synthesis of mitochondrial proteins?

miR-1 and miR-133a

Which two microRNAs are downregulated by resistance training to promote synthesis of contractile proteins?

mitochondrial biogenesis

The process by which muscle fibers increase their overall mitochondrial content and density

PGC-1 alpha

which master factor directly drives mitochondrial biogenesis and angiogenesis?

aerobic

where there is increased mitochondrial density, the body will increase the reliance on _________ energy pathways

cytosol

ADP in the ________ stimulates anaerobic pathways (CK and PFK)

mitochondria

ADP in the __________ stimulates aerobic respiration (isocitrate dehydrogenase and Complex IV).

PFK

what is the rate-limiting enzyme of glycolysis?

isocitrate dehydrogenase

What is the rate-limiting enzyme of the citric acid cycle?

ADP transporter proteins

an increase in ___ __________ _______ on the mitochondrial membrane enables faster entry of cytosolic ADP into the mitochondrial matrix post-training

mitochondrial biogenesis

physiological process by which skeletal muscle increases its total mitochondrial content and volume

mitochondrial biogenesis and angiogenesis

which two major functional adaptations are directly driven by activated PGC-1alpha?

false

true or false: endurance training-induced mitochondrial biogenesis reduces the total amount of ATP required to perform work at a given submaximal intensity?

aerobic

endurance training shifts energy production toward anaerobic or aerobic ATP production?

aerobic

ADP transported into the mitochondria stimulates ________ (anaerobic or aerobic) pathways

anaerobic

ADP remaining in the cytosol stimulates ________ (anaerobic or aerobic) pathways

true

true or false: increased mitochondrial content results in faster uptake of ADP into the mitochondrial matrix during exercise

faster

after training is there a faster or slower rise in O2 uptake, resulting a in a faster rise in VO2?

GLUT4

which membrane transporter facilitates glucose transport from blood plasma into muscle fibers?

FAT/CD36

which sarcolemmal transporter moves free fatty acids from blood plasma into the muscle cytoplasm?

CPT1 and CPT2

Which transport system is responsible for transferring fatty acyl-CoA across the mitochondrial membranes into the matrix?

CPT1

does CPT1 or 2 bring fatty acids from the blood into the muscle?

CPT2

does CPT1 or 2 bring fatty acids from the muscle into the mitochondria?

glucose to fat

endurance training shifts substrate utilization from _______ to ______ oxidation

decreases

does increases capillary density increase or decrease the BF?

false

true or false: endurance training causes complete fiber type transformation (e.g., converting Type II cells into true Type I cells) in humans?

slow myosin isoforms

endurance training promotes what type of myosin isoforms?

slow myosin isoforms

what type of myosin isoforms are most efficient because they perform more mechanical work per unit of ATP hydrolyzed

acid-base balance

endurance training minimizes ____-____ ______ disturbances by reducing systemic accumulation of lactate and hydrogen ions (H+).

H4

endurance training causes LDH to shift to the ___ isoform which has a low binding affinity for pyruvate which produces less lactate

ADP, NADH, pyruvate, and fatty acid

to reduce lactate formation during endurance exercise, mitochondria increase the transport of four key molecules/substrates across their membranes, name the 4

decreases

does increased FFA oxidation increase or decrease PFK enzyme activity, which slows glycolytic flux, reduces pyruvate formation, and lowers lactate and H+ production

antioxidants

______ neutralize free radicals to prevent lipid peroxidation, DNA damage, and protein oxidation

angiogenesis

the physiological formation of new capillaries from pre-existing vasculature

Vascular Endothelial Growth Factor (VEGF)

what primary growth factor coordinates the capillary branching process in response to endurance exercise?

PGC-1alpha

which transcriptional activator regulates VEGF gene expression and microvascular sprouting following endurance training?

O2 and fatty acids

having a higher capillary to muscle fiber ratio can help bring what 2 molecules into the muscle fibers?

VO2 max = CO x a-vO2 diff

According to Fick's equation, what formula defines VO2​ max?

SV

an increase in __ can increase CO

increases plasma volume and SV

what is the first cardiovascular adaptation that happens in the first 1-6 days of endurance training?

increase in SV

during the first 1 to 4 months of endurance training, what factor is almost entirely responsible for VO2​ max gains?

a-vO2 diff

after 32 months of endurance training VO2​ max gains result from combined improvements in both maximal CO and ______

EDV, afterload, and contractility

What three major physiological variables directly determine stroke volume?

kidneys

what organ helps to release hormones that retain sodium and water to compensate for sweating and capillary fluid shifting to buffer transient hypovolemia

decrease

does endurance training increase or decrease afterload?

group III and IV afferent fibers

which nerve fibers transmit peripheral metabolic signals from contracting muscle to cardiorespiratory control centers?

brainstem

where are cardiorespiratory control centers located in the central nervous system?

trained

does trained or untrained muscle generate weaker afferent signals to cardiorespiratory control centers at a given workload?

peripheral nerve

systemic response is regulated by _____ ___ feedback rather than central command alone

less

when there is more miRNA, will there be more or less protein synthesis?

neural adaptations

during the first 8 weeks of resistance training, strength gains are primarily driven by which mechanism?

muscle hypertrophy

after the initial 8 weeks of resistance training, further long-term increases in strength are primarily driven by what adaptations?

synchronously

is contraction force greater when motor units fire asynchronously or synchronously?

neural drive

the magnitude of the efferent neural output from the central nervous system (CNS) to stimulate muscle fibers

cross education

an increase in muscular strength observed in an untrained contralateral limb when only the opposite limb undergoes resistance training

true

true or false: trained muscles generate the same submaximal force with less EMG activity

increase

does resistance training increases or decrease the total number of motor units activated

rate coding

the frequency at which action potentials stimulate a muscle fiber to contract

false

true or false: Higher firing frequency allows more time for the muscle to relax between stimuli, causing force summation up to smooth tetanus.

false

true or false: Resistance training decreases the size of the NMJ and enhances acetylcholine release, improving the motor neuron's ability to activate contraction.

autogenic inhibition

a protective reflex mediated by GTOs that inhibits muscle contraction to protect muscles, bones, and connective tissue from damage under heavy stress

GTO

which sensory organ monitors muscle tension and transmits inhibitory signals to the central nervous system?

reduce

does RT increase or reduce neurological inhibition from GTOs, allowing the muscle to exert higher contractile force independently of hypertrophy

false

true or false: RT increases antagonist coactivation during maximal agonist contraction, reducing opposing resistive forces.

50-150%

by how much does Muscle Protein Synthesis (MPS) increase 1 to 4 hours after a resistance training workout?

30-48 hours

what is the typical total duration that Muscle Protein Synthesis remains elevated post-workout?

untrained

does MPS remain elevated for a longer duration in trained on untrained individuals?

translation

in cellular protein synthesis, what process converts mRNA into new structural protein inside the ribosome?

ribosomes

an increase in what muscle organelle is essential for muscle hypertrophy?

mTOR

what is the master regulator of MPS?

PA and Rheb

what two intracellular factors directly regulate the activation of mTOR?

TSC2

At rest, PA concentration is low, and Rheb is kept inactive because it is blocked by _____.

PA

following mechanoreceptor activation, what lipid messenger synthesizes in the cell membrane to directly bind and stimulate mTOR?

leucine

which amino acid is capable of stimulating mTOR activation independently of mechanical exercise tension?