physiological training: aerobic exercise (2)

training programs include

continuous dynamic exercise, high intensity interval training

2 factors influencing stroke volume

EDV and left ventricular volume increase

what does an increased stroke volume result in?

slower resting heart rate

what is the primary mechanism for end diastolic volume

increased blood volume

when does left ventricular volume increase

with prolonged training (months to years)

what happens to blood volume

plasma and RBC volume increase

2 types of cardiac hypertrophy

concentric hypertrophy and eccentric hypertrophy

overload for concentric and eccentric hypertrophy

concentric is pressure, eccentric is volume

physiological and pathological pressure overload

phys: strength training (static/isometric), weight training

path: hypertension, aortic constriction

heart description in concentric hypertrophy

thick walls, small cavities, parallel sarcomeres to increase myocyte cell width

physiological and pathological volume overload

phys: endurance training (aerobic/isotonic), swimming, long distance running, valve disease

heart description eccentric hypertrophy

thin walls, large cavities, sarcomeres in series increase myocyte cell length

2 factors influencing stroke volume

cardiac contractility and afterload

how does cardiac contractility influence stroke volume

improved “twist mechanic” in endurance athlethes

how does afterload influence stroke volume

less resistance to blood flow, reduction in sympathetic vasoconstriction in trained muscle, engage more muscles, make new capillaries and blood vessels

what does a-VO2 diff result from

a-VO2 diff results from increased extraction of O2 from blood

what is the primary mechanism for a-VO2 diff

increased capillary density

what effect does increased capillary density have

more blood supply, increased muscle blood flow, decreases diffusion distance to mitochondria, higher muscle contact

what does shift from fast-to-slow muscle fiber type depend on

magnitude depends on training duration and genetics

what happens when muscle capillarity increases

diffusion of O2 enhances, improved waste removal

2 subtypes of mitochondria

subsarcolemmal and intermyofibilar

mitochondrial biogenesis results in improved

oxidative capacity, ability to utilize fat as fuel

mitochondrial volume influence

increased volume = decreased cytosolic (ADP)

what happens when the rate of ADP transport into mitochondria increases

less phosphocreatine depletion and reduced stimulation of glycolysis (PFK)

what are the 3 effects on fuel utilization

1. increase FFA transport into muscle

2. FFA increase from cytoplasm to mitochondria

3. increased mitochondrial enzymes associated with beta oxidation

what are free radicals

unpaired electron in their outer orbital, highly reactive and promote damage

time course on training adaptations

muscle contraction activates primary and secondary messengers

when do mRNA levels peak

in 4-8 hours but return to baseline

2 primary signals for adaptation

increased calcium levels and AMP/ATP ratio, free radical production

where is calcium released from

sarcoplasmic reticulum

what increases the production of free radicals and oxidants

exercise

what is calmodulin dependent kinase (CaMK)

activated by cytosolic calcium increase, promotes PGC-1a activation

what is calcineurin activated by and what does it do?

calcineurin is activated by cytosolic calcium increases, participates in shift from fast to slow transition

what is nuclear factor kappa b (NFkB) activated by and promotes

activated by free radical increase and promotes antioxidant enzyme synthesis

what is mitogen-activated kinase activated and promotes

activated by free radial increase and promotes PGC-1a activation

what is PGC-1a activated by and what does it do?

activated by increases in CaMK, p38, AMPK and regulates mitochondrial biogenesis

what is AMPK activated by and stimulates

activated by shift in AMP/ATP ratio, stimulates glucose uptake and FFA oxidation during exercise