Energy Production/Expenditure (2) Flashcards
implications of ATP being a limited currency
ATP needs to be constantly resynthesized
ATP levels only decrease in skeletal muscle under EXTREME exercise conditions
body stores 80-100g of ATP normally- enough to power 2-3 seconds of maximal exercise
Why is phosphocreatine (PCr) the energy reservoir?
anaerobic splitting of phosphate from PCr= energy
cells store ~4-6x more PCr
PCr reaches its maximum energy yield in about 10s
Anaerobic glycolysis
rapid
results in pyruvate to lactate formation
5% of energy from original glucose molecule
Aerobic glycolysis
pyruvate to acetyle COa to citric acid cycle and electron transport of the remaining energy within glucose molecule (95%)
Citric Acid Cycle
second stage of carb breakdown to produce CO2 and hydrogen atoms within mitochondria
how many ATPs does the complete breakdown of glucose yield
34 ATPs
how much ATP does fat catabolism yield
460 ATP molecules
when does fat become the primary energy fuel for exercise and recovery
intense, long-duration exercise that depletes both blood glucose and muscle glycogen
what is the most plentiful source of potential energy?
stored fat
how does protein get used as energy
amino acids get converted- nitrogen removal
what does protein catabolism require and why?
an increase in body’s water needs because it yields waste products that get eliminated in urine
power generated by fat breakdown vs power generated by carb breakdown
power by fat breakdown is about half as much as carb breakdown (aerobic)
can fatty acid substrate make up for a decrease in muscle glycogen even if it’s around in large amounts?
nahhh b
where does fatty acid breakdown go?
accumulates in extracellular fluid and cannot enter the citric acid cycle
how much ATP and PCr does each kg of skeletal muscle contain, respectively?
3-8mmol ATP
4-5x more PCr
when does lactate acid accumulation occur?
50-55% of maximal capacity of aerobic metabolism in healthy, untrained persons
(at less than 50%, lactate accumulation=lactate disappearance)
when does the blood lactate threshold occur?
when muscle cells can neither meet energy demands aerobically nor oxidize lactate at its rate of formation
what is steady state aerobic metabolism?
a balance between energy required by working muscles and ATP production in aerobic reactions
there is no appreciable blood lactate acid accumulation
what are two steady state aerobic metabolism limiting factors?
fluid loss and electrolyte depletion
maintaining adequate reserves of both liver glycogen and muscle glycogen for CNS function and exercise power, respectively
what are two factors that help to explain athlete’s high steady-rate levels?
- high capacity of the central circulation to deliver oxygen to working muscles
- high capacity of the active muscles to use available oxygen
what is the oxygen deficit?
difference between total oxygen consumed during exercise nd the total that would have been consumed had steady-state oxygen uptake been achieved at the start of exercise
which individuals reach steady state first?
endurance-trained individuals
what three adaptions increase an individual’s total capacity to generate ATP aerobically?
- more rapid increase in muscle bioenergetics
- more rapid increase in overall blood flow
- disproportionately large regional blood flow to active muscle complemented by cellular adaptions
when does VO2 max occur?
oxygen uptake plateaus or increases only slightly with additional increases in exercise intensity- range!!
