Carbs + Exercise

Question 1

what do carbs before exercise do and during

Answer 1

before- replenish muscle, liver glycogen stores

during- maintain blood glucose for glucose ox.

Question 2

role of muscle glycogen/ how much we store/ exercise intensity usage

Answer 2

readily available for working muscle
300-400g

@ low- most energy derived from ox phosphorylation

@ high- oxidation of carbs fat can’t keep up, muscle glycogen becomes important

Question 3

role of Liver glycogen/ how much we store/ exercise intensity usage

Answer 3

main role to keep constant blood glucose lvl (prevent hypoglycaemia)
80-110g
As exercise intensity increases more glucose released

@ rest- 60% glucose from liver glycogenolysis

@>75- 90% from liver glucose genolysis

Question 4

T/F- is 40-50% carbs in diet enough for repeated training days

Answer 4

F

Question 5

Classical super compensation model( how is it done and results)

Answer 5

results in high muscle glycogen conc. past norm lvls

-depletion of carbs first, then 3 days very high carbs
allows muscle glycogen to bounce back higher

-only 2 training days tho

Question 6

moderate super compensation model (how its done and results)

Answer 6

training reduces gradually, carbs raise gradually
-studies found can work for elite athletes in only 1-2 days
-done more
suitable for marathon + triathletes (not explosive athlete)

Question 7

Lukes study- what is it on, background(what is it important for), and his study +results

Answer 7

Betaine supplementation
past studies found some improvement in performance
is a methyl donor and important for fluid balance

study q- effects on running performance lactate prod

didn’t improve performance during SIT, lactate sig lower but didn’t have an effect on performance

Question 8

benefits of carb intake hours before exercise

Answer 8

increased carb oxidation + execrated glycogen breakdown during ex

blunting of fatty acid mobilization, + fat oxidation

Question 9

benifits of carb intake 30-60 mins before

Answer 9

prevents hypoglycaemia (increase plasma glucose + insulin)

Question 10

factors determining glycemic response during ex.

Answer 10

• stim. effects of insulin +catecholamines on liver glucose output
• magnitude of ongoing absorption

Question 11

what does carbs during exercise do

Answer 11

maintains blood glycogen + high levels of carb ox

• glycogen sparing
• promotes glycogen synthesis during ex

Question 12

exogenous carb oxidation- amount of carbs should be eaten, type of carbs that oxidizes at higher rate
and how exercise intensity affects it

Answer 12

amount- consume 70g/h for optimum delivery

type- glucose oxidazes at higher rates then fructose/galactose

exercise intensity- high intensity= more dependence on carbs (more muscle glycogenolysis+ plasma glucose oxidation)

Question 13

limits to exogenous carb ox

Answer 13

gastric emptying
digestion of carbs/intestinal absorption
glucose uptake

Question 14

rate of glycogen synthesis after exercise depends on

Answer 14

-availability of glucose
-transcription of glucose into cell
activities of enzymes

Question 15

name of active/inactive glycogen synthase

Answer 15

I = active
D= inactive

Question 16

rapid phase of glycogen synthesis post ex. ( what is glycogen synthase doing + other enzymes needed)

Answer 16

when muscle glycogen low= more I form
glucose only formed if substrate (UDP-glucose) available
after ex. abundance of GLUT-4 facilitates uptake of glucose

Question 17

what happens during slow phase of glycogen synthesis after ex.

Answer 17

dependent on circulating insulin which increases GLUT 4 which increases glucose transport to muscle