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Exercise Physiologist
Everybody is different…however i would suggest a more protein based snack 2-3 hours pre-game such as tuna, yoghurt or nuts. The reasoning behind this is all about insulin. When we eat carbohydrates (such as pasta, fruit) our body produces insulin…a hormone which switches our body to use glucose as fuel (as opposed to fat). This means that you will more then likely be using your muscle glucose stores (glycogen) early on in the game and during low intesities instead of the preferred fuel -fat. Thus leading to early glycogen depletion which casues a decline in performance and fatigue ….athletes describe it as ‘hitting the wall’. Give it a go, you may be suprised:)
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Dietitian, Nutritionist, Sports Dietitian
Kirsty, your almost on the right track here but, It is important to remember that as exercise intensity increases our bodies rely more on carbohydrates as a fuel source. The best snack before exercise should be predominantly carbohydrate based to give the body the fuel it needs to get through the game or training session.
When choosing a pre-game/training meal, snack and fluid it must:
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Exercise Physiologist
Chris, I definitely agree with you…as exercise intensity increases glucose becomes the predominant fuel. However when you think about the energy demands of a game of soccer (http://www.brianmac.co.uk/football/energy.htm) I believe the focus should be on glycogen preservation for those higher intensity bursts. Hungarian researcher Apor (1988) and Ohashi et al. (1988) both describe football as comprising sprints of 3 to 5 seconds interspersed with rest periods of jogging and walking of 30 to 90 seconds. Therefore, the high to low intensity activity ratio is between 1:10 to 1:20 with respect to time.
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Dietitian, Nutritionist, Sports Dietitian
Kirsty, of course if we can hold onto more glycogen it would definately improve performance and delay the onset of fatigue. Soccer is a sport that involves both endurance interspersed with high intensity efforts throught the game.
In regards to insulin, its a storage hormone, therefore when raised levels appear in the blood, it promotes glucose storage (as glycogen) not the breakdown for energy. Glucagon, the hormone released when blood glucose levels are low promotes the breakdown of glycogen to glucose to fuel our bodies cells. I think you may have had the two confused.
Many studies have shown that by ingesting carbohydrates prior to a game will help to prevent fatigue and a decline in performance therefore carbohydrates should form a greater proportion of a pre-game meal compared to protein. Protein is important in the recovery phase after a game or training session as it helps to repair damaged muscle, but it also needs to be consumed with a source of carbohydrate to allow the bodies cells to uptake the amino acids.
Rather than sourcing information from brianmac.co.uk, I would suggest taking a look at the sports dietitians Australia website: www.sportsdietitians.com.au and having a look at some of their factsheets on how to properly fuel before, during and after sport.
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Exercise Physiologist
Agreed Chris, insulin is responsible facilitating glucose entry into the cells for glycogen synthesis…However it is also well known that it facilitates glucose entry into the cells for glycolysis (glucose breakdown for fuel) and inhibits lipolysis (break down of fats for fuel).
By facilitating the use of glucose for fuel during exercise when glute 4 transporters are present during exercise as well as inhibiting lipolysis means that that body is inclined to use glucose when insulin is circulating. So even at low intensity’s they can use glycogen stores when they should be utilizing fat.
Horowitz et al (1997) demonstrated that a reduction in fat oxidation during exercise after the ingestion of carbohydrate requires a compensatory increase in carbohydrate oxidation to maintain energy production and the source of the increase in carbohydrate oxidation is partly from glycogen (http://ajpendo.physiology.org/content/273/4/E768.full).
In saying that it all depends on an individual’s metabolic response to insulin and exercise. I know clients who have responded well to both regimesJ
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Dietitian, Nutritionist, Sports Dietitian
Your previous answer you recommended that this fellow should have a high protein snack before his training session or game. From a sports nutrition point of view and having consulted and worked with sport dietitians in top level sport (AFL, Triathlons) the pre-game meal or snack should be predominantly carbohydrate based.
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