Final Flashcards
(124 cards)
Total Energy Intake (individual considerations and sport considerations)
- needs can be quite variable in athletes, so consider recommendations relative to body size and expenditure, i.e. in some sports like the Tour de France, high energy expenditure is hard to fuel, leading to challenges for weight gain and loss
Macro intake CHO - general other shit
- staying below anaerobic threshold is better to spare glycogen
- there is not different between liver and muscle stores of glycogen except for the fact that liver is more accesible quicker
-we need about 12-16 grams of CHO per KG of muscle when its wet when its dry multiple it by 4.5 so if someone has 25 kg of muscle they need 300-400 grams of CHO - liver glycogen has a higher concentration than muscle but a lower total amount of about 100 g, which can be depleted to below 20 after an overnight fast, so try to spare liver glycogen as much as possible cuz its so easy to use… if you running a marathon the next day want to make sure you have as high of liver glycogen as possible fore but actually you can regen liv it so eat a lot the night beforer glycogen stores fairly quickly. Therefore, it is important to get glycogen which is important for everything
Macronutrient. intake (CHO) - Acute effect of endurance exercise
- High intensity exercise depletes liver glycogen by 50 percent
- supramax repetitive work also depletes it
- time to exhaustion is directly related to restiing glycogen stores
-High glycogen store in liver fast quick source of energy
Other effects of endurance exercise - glycogen sparing
improved mitochondrial metabolism enhances lipid oxidation
larger glycogen stores in skeletal muscle
Macro - blood glucose levels with training
- you want to maintain glucose levels as much as possible with proper refuelling
- if doing suer high intesnity activity glycogen gets quickly depleted even more important as intensity goes up liver puts more glycogen into blood stream
High vs low CHo diets in marathoon runners study
- marathon runners for those eatinig high CHO diet their glycogen stores recovered stayed relatively constant compared to those on a low CHO diet
Glycemic index What can influence the GI of a food
-Pure glucose is that standard reference (100)
- biochemical structure of the CHO
- the absorption process
- size of the food particle
- congestion of fat fibre or protein
Glycemic index and load
- Gi = area under curce (AUC) times 50g other CHO (like fructose) / AUC times 50 glucose times 100
Gi 0-100 50 g is standard - less interested in GI and more in glycemic load
Glycemic load = GI times gCHO/100 - how much is available in the system for energy
Foods with high glycemic index fast response to blood glucose values
-average plasma is 6 if you injest lots of cho like gummy bears there is a sharp spike in blood glucose cause body releases insulin to reduce those levels to normal but sometimes the insulin being released cause a rapid drop in glucose which can result in glucose levels below where you started and this mainly occurs when you eat up to an hour before exercise, neveer want to start with low glucose
- can monitor it by eating a little less maintain reponse rather than sharp drop off
- ideally, start the race with the highest blood glucose possible. Eat gummy bears 30 minutes before as soon as you start to exercise, epinephrine release stops from being released; then you get to maintain blood glucose for longer periods of time
Glycemic index - values
- Low GI - less than 55 - most fruits veg expet potatoes, whole grains, basmati rice and pasta
- medium - 56-70 - sucrose, croissant, brown rice
- high - over 70, corn flakes baked potato, soe white rice like jasmine, and white bread
General CHO intake guidelines
- ACSM says 6-10 g/kg of body weight but depends on type of sport playing doo like
daily moderate duration low intensity 5-7
daily mod to heavy endurance 7-12
daily extreme 4-6 hours 10-12 plus
CHO days before competition
- goal - replenish and maximize muscle glycogen
- Supercompensation - CHO loading - increse time to fatiuge by 20 percent, decrese time to completed task by 2-3 percent, mostly for activities longer than 60-90 mins
- other considerations
5-7 days of supercompensation is not always feasbile
if each g of CHO is stores with 2-3 grames of water there is a balence between whats the most advanagoues thing like for a sprinter the glycogen or the weight
Carb loading
- some studies suggest muscle glycogen doubled compared to normal resting levels
- slowly increase the amount of CHO in your diet while reducing the amount of training you are doing as well as best results for comp
Potential issues with classical supercompensation
- hypoglycemia when CHO is low
- may not be practical (meal prep)
- GI problems
-Mood
-tenseness without training
-randomized to 5 days of high 75% vs lowe session 75% for 1 hr then. did muscle biopsy also, did time to fatigu 55% CHO exercise at 85% max
Men vs Women
- showed that for men that a low vs high CHO intake incresed the time to fatiuge greatly
- for women increse in glycogen in the muscle that same change was not prevalent did not increse time for fatiuge
why might glycogen stores be different in men vs women
- women tend to have a greater reliance on fat oxidation
- CHO loading may increse weight - issues with complicance ( prolly not)
- if CHO loading does not increse muscle glycogen then where tf does it go
CHO loading - muscle vs liver glycogen
-Muscle glycogen is often super compensated before full recovery of liver glycogen ie if boh are depleted than muscle will fill faster
fructorse fruits and honey vs glucose like pasta
- fructose can lead to slower muscle glycogen but similar liver glycogen replenishment so if you want CHO fast then get glucose
CHO hours before comp
- goal - replenish maximise liver glycogen and increse glucose delivery to muscle
- 0-4 hrs before exercise
- meal 3-4 hrs before exercise can increse muscle glycogen - however s run is early am might not be possible most important thing is risk benefit sleep or replenisment - if you are doing a more cognitive sport like team sports sleep may be more importat then vs a run
- 200-300g 3-4 hrs before exercise
- some controversy due to glucose induced insulin release w high GI hypoglycemia excessive skeletal muscle uptake and blunted lipolysis
- low GI vs high Gi to minimise hypoglycemia
- timing goal is to not feel hungry or have undigested food in stomach - more benefits if CHO cannot be consumed during exercise
individuals who ate a high GI index meal 3 hrs before running fatiuge meaning they tired out faster than those who ate a low GI index food
CHO during comp
- 30-60 g/hr or .7g/kg/hr liquid or solid benefits high intensity long duration and extends time to exhaustion
- trianing state does not imporve ability to utilize CHO - metabolism cannot be trained
- better to provide CHO every 15-20 mins than after 2 hrs
- Dont consume things with high fructose - as its slower to absorb
- controversial for events lasting less than an house there have been shown evidence of beenfits with just rinsing mouth with CHO bevy
- glycemic index - remember exercised induced epinephrine inhibits insulin release
Cho during comp - what is the exception to fructose
- Evidence has shown that adding some fructose in can actually help in peak oxidation the max glucose you can oxidise is 1.2 g/min no matter how much more you eat this number never changes - BUT if you intake some fructose alongside it it can actuallly increse the CHO oxidation slightly because of different transporters of glucose and fructose and different receptos allowing for slightly higher oxodation
CHO during comp - what is the maximal amoutn of intake
70g/hr - the max you would ever want to digest intake during comp like a 1-litre sports drink, 600ml of cola etc. ACSM recommends .7g/kg/hr
CHO intake after exercise
- Goal - replensish muscle and liver glycogen -
create positive glycogen repletion enviroment (increse insulin icnrese tissue sensitivity to insulin reduce catecholamine and increse glycogen synthase - greater insulin respnse means a greater glycogen storgae however not supported by research
- easiest way to increse insulin is to EAT
- ACSM says to consume 1-1.5g/kg moderate to high GI CHO within 30 mins and then every 2 hrs for up 2 6 hours until 500g or 701-g/kg has been ingested
- this is very dependent on the activity performed and the next activity to be performed
WHy CHO load after comp?
- Replenish depelted liver and muscle glycogen
- glycogen stores is directly related to performance
What affects the rate of glycogen syntheiss
- availibility of glucose
-insulin - prior exercise - increse insulin sensitivity
CHO intake after exercise - timing
- Rapid phase of glycogen syntheisis is 1-2 hours glycogen synthase (exercise upregulates this rate limiting enzyme and glucose availibility)
- Slow phase of glycogen synthesis - insulin availibility
- eat immediately after you get the greatest rate of glycogen synthesis
- wait 2 hours, and it’s much slower