Muscle Metabolism- Sprint and Distance Flashcards
what can muscle use as fuel?
anaerobic or aerobic metabolism
- creatine phosphate
- glucose
- muscle glycogen
aerobic metabolism only
- fatty acids
- ketone bodies
- amino acids
where does AMP come from in muscles?
combination of 2 ADP by adenylate kinase- makes an ATP and an AMP
what does AMP do?
allosterically activates phosphofructokinase-1 to stimulate glycolysis
what does phosphofructokinase-1 do?
stimulates muscle phophorylase b kinase- activates glycogen phosphorylase to break down glycogen
when is epinephrine released?
intense exercise
what does epinephrine do?
binds beta adrenergic receptors and activates the cAMP/PKA pathway which phospohrylates phosphorylase b kinase, which activates glycogen phophorylase
is muscle responsive to glycogen?
no
only epinephrine
what 3 things activate muscle glycogenolysis?
AMP
epinephrine
Ca
how do nerves stimulate muscle glycogenolysis?
increase cytoplasmic Ca which stimulates glycogen phophorylase b kinase (activates glycogen phosphoylase)
what source of energy is used in sprinting?
anaerobic metabolism of muscle only energy supply
what are the sources of ATP in sprinting muscle? how long do they last?
ATP pool- 1 sec
creatine-phosphoate pool- 4 sec
glycogen
why are fatty acids and ketone bodies not used in sprinting?
not enough time for them to diffuse into tissues
limited perfusion prevents diffusion anyway
what is the basis of fatigue when sprinting?
decreased pH
- limits force of contractions
- inhibition of PFK1 which decreases rate of glycolysis
what may combat fatigue onset in sprinting?
dietarty creatine and NaHCO3
what is the source of energy during prolonged exercise?
aerobic metabolism of muscle glycogen, glucose, fatty acids/ketone bodies (60%)
what type of fibers are primarily found in sprinters?
white fibers- few mitochondria
what type of fibers are primarily found in endurance athletes?
red fibers- lots of mitochondria
what processes are activated by epinephrine?
muscle glycogenolysis
liver glycogenolysis
TAG lipolysis
what processes are activated by glucagon?
liver glycogenolysis and gluconeogenesis
TAG lipolysis
NO effect on muscle
how is lactate production related to length of exercise?
decreases with increase duration because anaerobic glycolysis is decreased
what is the basis of fatigue in endurance exercise?
fuel and O2 depletion
what happens when glycogen is depleted?
major energy reduction
switch to fatty acid and blood glucose for energy source
what happens as prolonged exercise becomes more vigorous?
muscles get more hypoxic, switch to anaerobic metabolism
fatty acids aren’t used as efficiently and muscle is more reliant on blood glucose (liver glycogenolysis and gluconeogenesis)
what are the current recommendations for carbohydrate loading prior to endurance events?
high carb diet during training
increase to 70% carbs and decreased training 2-3 days prior to event
results in 3 times more glycogen stores
what is the respiratory quotient?
ratio of CO2 exhaled to O2 consumed
how many CO2s are released during aerobic metabolism of glucose?
3- PDH, isocitrate dehydrogenase, and alpha ketogluterate dehydrogenase
how many CO2s are released when fatty acids are used?
2- skipped PDH step (isocitrate dehydrogenase and alpha ketogluterate dehydrogenase)
what happens to the RQ with increased exercise duration?
decrease because less CO2 is being produced when muscles switch from glycogen to fatty acids for energy
