Exercise and metabolism Flashcards
Which energy pathways can be anaerobic?
ATP>ADP+Pi
PCr+ADP>ATP+Cr
Glycolysis
Which energy pathways are only aerobic?
Kreb’s cycle
Oxidative phosphorylation
Where do anaerobic reactions occur?
Cytoplasm
Why does a particular energy system fuel different forms of exercise?
dependent on the rate at which ATP can be resynthesised to fuel the rate of muscle contraction
Slowest to fastest processes that resynthesise ATP
Fat oxidation, glucose oxidation in blood, glucose oxidation in cells, glycolysis, PCr breakdown (which is instantaneous)
How long does the ATP system power exercise for and which enzyme is responsible?
1-2s
ATPase
How long does the phosphagen system power exercise for and which enzyme is responsible?
10-15s
Creatine kinase
How long can glycolysis power exercise for?
3-5min
What is aerobic glycolysis used for?
low intensity exercise where pyruvate is passed along to the citric acid cycle and hydrogen is temporarily accepted by NAD
What is anaerobic glycolysis used for?
High intensity exercise where hydrogen binds to pyruvate and lactate is produced via lactate dehydrogenase
Lactate vs lactic acid
lactate is C3H5O3 whereas lactic acid is C3H6O3
How much ATP is produced in the citric acid cycle per glucose?
2
How much ATP is produced in oxidative phosphorylation per glucose
30-34
What is the pattern in % of anaerobic and aerobic pathways used as exercise duration increases?
aerobic increases while anaerobic decreases but always a higher % of anaerobic
Where can we get creatine from our diet?
Meat, fish, poultry
How can the body resynthesis creatine
from non essential amino acids
Where is 95% of creatine stored
skeletal muscle
How is creatine sold?
creatine monohydrate
CrH2O
Why is creatine that is sold often found with carbohydrates?
insulin aids the absorption of creatine
Mechanisms of creatine enhancing performance?
increase rate of ATP re-synthesis
delay depletion of PCr
less reliant on glycolysis so less lactate build up
increase training intensity
What is the effect of intracellular acidosis?
reduced sensitivity to Ca2+
How is acidity counteracted to improve performance?
supplementation with bicarbonate which neutralises excess stomach acid in indigestion. It enters muscle cells, increasing extracellular pH which causes H+ to leave muscle cells faster
Why are small doses of bicarbonate used?
CO2 produced which causes gastrointestinal stress
