4 ms·

Might be lacking glucose; I believe that is why marathon runners eat glucose before they run.

zatkin 10y ago
What do you mean by glucose exactly? What kind of foods should I be eating? I usually just get whatever for lunch at my company - tacos, Indian food, whatever is being served.
- ihsw 10y ago
  Depends, how long are you training? I'm not familiar with the effort required for mountain climbing, but eating a varied meal beforehand would help. Personally, a peanut butter sandwich, banana, half an avocado (depending on the size of the avocado), tall glass of milk, and celery with hummus will prepare me well for the following few hours. Adjust this for yourself as needed. A healthy balance between fat, fiber, carbs, and protein is what you're looking for. I can't give any any hard numbers but a good macro-nutrient balance is the first step to a healthy diet, with the second step being fresh food.
- mpbm 10y ago
  From experience, you'll need to spend a lot of time learning about macros before advice on what food to eat will do you much good. For example, if someone says "eat two cups of green salad with 2 tablespoons of olive oil" you'd have to A) already know what all that means or B) spend a couple hours researching how to estimate volume and source predictable ingredients and prepare them or C) just wing it and end up with some bullshit from a store that's lettuce covered in croutons, cheese, and sugary dressing. A good heuristic is that if you bought it, or it was bought for you, it's got too much refined carbohydrate in it and the serving size is too large. This is because to consumers value=(volume*taste)/dollar
ihsw 10y ago
This is probably it -- after exhausting the contents of the digestive tract, the body resorts to glycogen reserves in muscle and the liver. Your glycogen reserves are your "blood-sugar" and consuming them requires a burst of oxygen, so depleted oxygen typically follows low blood-sugar, ergo yawning. Energy gels are usually high-energy but low-everything-else, which is probably what the parent is referring to ("eat glucose"). This is to supplement blood-sugar levels without affecting the digestive process too much, or, more to the point, without affecting their marathon performance.
- fpoling 10y ago
  Only muscles can use glycogen stored in muscles. Brain, digestive tract can only use glycogen energy from liver. Also note that eating just glucose or table sugar before marathon also helps to minimize digestion energy expenditure so most stored glycogen in liver will be used on brain and nervous tissue, not on processing food.
tigerBL00D 10y ago
Some corrections from the point of view of an endurance athlete (triathlon). First of all you don't really "eat glucose", that would be an oversimplification. Glucose is produced by your own body when metabolizing carbohydrates. As a backup mechanism your liver can also produce glucose by converting amino acids (muscle) and even fat, a process known as gluconeogenesis. Now, if we replace "eat glucose" with "eat carbohydrates", then the statement is still not quite accurate. Experienced marathon runners (and other endurance athletes) will not consume carbs before the run because doing so would spike insulin and effectively shut down breakdown of fatty acids in the liver. Liver can more or less either convert glucose to glycogen and fat, or break down fat, and is not great at doing both simultaneously. Maintaining fat metabolism is hugely important when going the distance since it's the largest energy reserve available in your body (50,000+ calories vs <2000 calories as glucose). Marathon runners consume moderate amounts of carbohydrates DURING exercise when insulin response is blunted. The idea here is to maintain glucose levels and avoid going into hypoglycemic state (low blood sugar). Ingesting moderate amounts of simple and complex carbs during exercise spares glycogen without necessarily spiking blood glucose to where liver has to regulate toxicity. This way you can keep on going longer.
- CarpetBench 10y ago
  > As a backup mechanism your liver can also produce glucose by converting amino acids (muscle) and even fat, a process known as gluconeogenesis. Just a quick note, and your explanation is fantastic otherwise: this isn't quite correct. The (human) liver doesn't use fat directly for gluconeogenesis. It's just not efficient for humans: We wouldn't gain enough energy from it. The liver uses fat indirectly through glycerol (which is a product of fatty acid catabolism), but it's important to draw a distinction here because this is why ketosis occurs - if the liver could efficiently break down fat directly, ketosis would never happen at all! Most tissues would much rather use glucose directly if it's an option. While muscle breakdown occurs in small amounts normally it's mostly a last resort that occurs after an extended period of starvation. Which makes sense: You wouldn't want to break down the thing (skeletal muscle) you need to get more food except as a last resort. The amino acids involved in more typical gluconeogenesis largely come from other sources.

What do you mean by glucose exactly? What kind of foods should I be eating? I usually just get whatever for lunch at my company - tacos, Indian food, whatever is being served.

ihsw 10y ago
Depends, how long are you training? I'm not familiar with the effort required for mountain climbing, but eating a varied meal beforehand would help. Personally, a peanut butter sandwich, banana, half an avocado (depending on the size of the avocado), tall glass of milk, and celery with hummus will prepare me well for the following few hours. Adjust this for yourself as needed. A healthy balance between fat, fiber, carbs, and protein is what you're looking for. I can't give any any hard numbers but a good macro-nutrient balance is the first step to a healthy diet, with the second step being fresh food.
mpbm 10y ago
From experience, you'll need to spend a lot of time learning about macros before advice on what food to eat will do you much good. For example, if someone says "eat two cups of green salad with 2 tablespoons of olive oil" you'd have to A) already know what all that means or B) spend a couple hours researching how to estimate volume and source predictable ingredients and prepare them or C) just wing it and end up with some bullshit from a store that's lettuce covered in croutons, cheese, and sugary dressing. A good heuristic is that if you bought it, or it was bought for you, it's got too much refined carbohydrate in it and the serving size is too large. This is because to consumers value=(volume*taste)/dollar

ihsw 10y ago

This is probably it -- after exhausting the contents of the digestive tract, the body resorts to glycogen reserves in muscle and the liver. Your glycogen reserves are your "blood-sugar" and consuming them requires a burst of oxygen, so depleted oxygen typically follows low blood-sugar, ergo yawning. Energy gels are usually high-energy but low-everything-else, which is probably what the parent is referring to ("eat glucose"). This is to supplement blood-sugar levels without affecting the digestive process too much, or, more to the point, without affecting their marathon performance.

fpoling 10y ago
Only muscles can use glycogen stored in muscles. Brain, digestive tract can only use glycogen energy from liver. Also note that eating just glucose or table sugar before marathon also helps to minimize digestion energy expenditure so most stored glycogen in liver will be used on brain and nervous tissue, not on processing food.

tigerBL00D 10y ago

Some corrections from the point of view of an endurance athlete (triathlon). First of all you don't really "eat glucose", that would be an oversimplification. Glucose is produced by your own body when metabolizing carbohydrates. As a backup mechanism your liver can also produce glucose by converting amino acids (muscle) and even fat, a process known as gluconeogenesis. Now, if we replace "eat glucose" with "eat carbohydrates", then the statement is still not quite accurate. Experienced marathon runners (and other endurance athletes) will not consume carbs before the run because doing so would spike insulin and effectively shut down breakdown of fatty acids in the liver. Liver can more or less either convert glucose to glycogen and fat, or break down fat, and is not great at doing both simultaneously. Maintaining fat metabolism is hugely important when going the distance since it's the largest energy reserve available in your body (50,000+ calories vs <2000 calories as glucose). Marathon runners consume moderate amounts of carbohydrates DURING exercise when insulin response is blunted. The idea here is to maintain glucose levels and avoid going into hypoglycemic state (low blood sugar). Ingesting moderate amounts of simple and complex carbs during exercise spares glycogen without necessarily spiking blood glucose to where liver has to regulate toxicity. This way you can keep on going longer.

CarpetBench 10y ago
> As a backup mechanism your liver can also produce glucose by converting amino acids (muscle) and even fat, a process known as gluconeogenesis. Just a quick note, and your explanation is fantastic otherwise: this isn't quite correct. The (human) liver doesn't use fat directly for gluconeogenesis. It's just not efficient for humans: We wouldn't gain enough energy from it. The liver uses fat indirectly through glycerol (which is a product of fatty acid catabolism), but it's important to draw a distinction here because this is why ketosis occurs - if the liver could efficiently break down fat directly, ketosis would never happen at all! Most tissues would much rather use glucose directly if it's an option. While muscle breakdown occurs in small amounts normally it's mostly a last resort that occurs after an extended period of starvation. Which makes sense: You wouldn't want to break down the thing (skeletal muscle) you need to get more food except as a last resort. The amino acids involved in more typical gluconeogenesis largely come from other sources.