Carbohydrates Flashcards
muscle glycogen synthesis rates when no cho is consumed after exercise
7-12 mmol/kg dw/hour
muscle glycogen synthesis rates with cho supplementation after exercise
20-50 mmol/kg dw/hour
conversion factor for dry weight and wet weight
4.28
how much cho required to maximise post exercise glycogen resynthesis rates
adequate amounts believed to be around 0.7g/kg bw/hour of glucose
How does ingestion of sucrose effect muscle glycogen
same as glucose no further benefit after 0.7g
How does fructose differ from glucose and sucrose
smaller blood glucose and insulin response, uses glut-5 transporter and is taking up by liver instead of muscle
how does insulin respond to glucose, sucrose and fructose
follows similar response as it tries to dispose and store the glucose
Should cho be fed immediately or can they be delayed
no effect of immediate feeding at 8 or 24 hours, only relevant when you do not have a long recovery period otherwise no benefit on performances
Does frequency of feeding effect glycogen storage
no effect of frequency when high carb diet is fed over a period of 24 hours
what is glycogen synthase responsible for
muscle glycogen synthesis
how is glycogen synthase effected by cho+protein intake
unregulated by insulin, intake of protein+carbs upregulates insulin in turn upregulating glycogen synthase
higher muscle glycogen storage, due to insulin effect on glycogen synthase
when does glycogen synthetic response become saturated
1.2g/kg/h of carb additional protein ain’t necessary
not related to saturation of insulin response, saturation response at the muscle
post exercise muscle glycogen synthesis with cho+protein
suboptimal intake of cho, protein may enhance glycogen resynthesis
due to enhanced insulin secretion and it’s effect on glucose uptake and glycogen synthase (GLUT-4 responsible for glucose uptake in skeletal muscle under action of insulin is translocation to cell membrane, fuses with membrane cells it’s able to take glucose up)
large amount of cho provided 1.2g/kg/hour at regular intervals 30 mins, addition of protein does not increase muscle glycogen resynthesis despite higher insulin
recommendation is 1.1-1.2 g/kg/hour for first 4 hours
(protein consumption not irrelevant needed for muscle protein synthesis)
what transporter does glucose use
sglt1 and glut2
what transporter to does fructose use
glut5
what cho does the liver take up
fructose and galactose
what are fructose and galactose effective at
restoring liver glycogen
how much carbs should you take in
enough to match fuel needs of training and subsequent glycogen restoration
failure to consume sufficient cho will lead to depletion of muscle glycogen and reduced quality of training
how should cho guidelines be given
in absolute quantities (g/kg)
body size and composition is why
how much glycogen does the liver store
80g
how much glycogen does muscle store
300-800g
how much triglyceride does muscle store
300g
how much triglyceride does adipose tissue store
10000-15000g
what happens when blood glucose increases
pancreatic beta cells produce insulin
what is the effect of insulin
effect the liver to reduce liver glycogen breakdown and reduce gluconeogenisis (production of glucose), control blood glucose
target skeletal muscle to drive glucose uptake
insulin inhibits lipolysis and therefore free fatty acid availability
what does an increase in glycerol indicate
glycolytic rate accelerating
stable in low intensity exercise
increase with moderate intensity exercise
effect of being fed vs unfed on ffa
when fasting ffa climbs as lipolysis rate is sufficient to supply ffa in surplus of what is required
fed ffa reduce as capable of been taking and utilised as a fuel as well as insulin suppressing lipolysis rate
does increased ingestion of cho lead to increased oxidation of cho
no
what effects gastric emptying
ingestion volume
concentration of ingested products, more concentrated less rate of emptying
what’s the maximum oxidation rate of cho
1g/min no matter how much you increase intake by
which cho are rapidly oxidised (1g/min)
glucose , sucrose, maltose, lactose, maltodextrin, soluble starch
which cho are oxidised at a lower rate (0.5g/min)
galactose, fructose, insoluble starch
how much carbohydrate should we consume
1g/min or 60g/hour during exercise
1 litre of typical sports drink (6-7%)
2 gels/hour of typical gel (contains 30g)
0.5 lites plus 1 gel per hour
what limits exogenous carbohydrate oxidation
intestinal absorption
how can we theoretically increase intestinal absorption of cho
intake multiple cho that use different transporters such as glucose (sglt1) and fructose (glut5)
how can we maximise cho oxidation
glucose and fructose
glucose sucrose and fructose
updated cho recommendations
30-75 mins - single or multi transportable cho
1-2 hours - 30g/hour of single or multiple
2-3 hours - 60g/hour of single or multiple
2.5+ hours - 90g/hour of multiple transportable cho
does caffeine increase substrate metabolism
no
how does caffeine work
adenosine receptor antagonism - blocked by caffeine so reduces feeling of fatigue, perception of effort
increase in force production
increase calcium prouctio
what is glycerol a measure of
lipolysis
effect of feeding on glycerol
fed - suppressed due to rise in insulin
fasted - increases as mobilising of fatty acids
how much of milk is casein and whey
20% casein (slow - acidic environment of stomach) 80% whey (fast)
what do amino acids do
stimulate protein synthesis and provide substrate to build muscle
what does insulin do to muscle
suppresses protein breakdown
resistance exercise + feeding =
increase in muscle protein synthesis
