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From Fellrnr.com, Running tips
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==Objectives for Fueling==
* '''Carbohydrate for the brain.''' Without sufficient blood sugar, mental functioning degrades. This can impact mood, creating depression, or cognitive reasoning, which impairs judgment. In some cases it can reduce motor skills, making trail running harder.
* '''Carbohydrate for muscle function.''' Muscles require both carbohydrate and fat to function, but it is the carbohydrate that is normally the limiting factor. Authorities estimate most people have about 2,000 Calories of stored carbohydrate (glycogen[[Glycogen]]). * '''[[Protein]] to protect muscles.''' Consuming protein [[Protein]] has been shown to protect the muscles from damage during exercise and to improve recovery. [[Protein]] and carbohydrate together have also been shown to improve endurance more than carbohydrate alone.
* '''Fat for muscle function.''' The human body contains more stored fat than needed for even extreme endurance runs. However, I suspect that our bodies have a limited rate at which body fat can be burned, so consuming fat may be beneficial.
==Constraints==
* '''Intensity.''' The biggest influence on fueling is the running intensity. Digesting fuel requires blood, oxygen and energy.
** Running at very high intensity may prevent any digestion or absorption, even of water. If fuel is consumed before running at this intensity may result in nausea or vomiting. Luckily, this pace generally does not require any fueling during the run, as the duration is short. The specific pace will vary from person to person, but would typically be mile to 10k race pace.
** Running at mid intensity generally allows for the consumption of simple carbohydrates or simple carbohydrate/protein [[Protein]] mix. This fuel will offset the limited carbohydrate stores in the body. Again, specific paces depend on the individual, but are likely to be half marathon to 50K pace for most people. ** Running at low intensity often allows the digestion of complex food. The longer duration of lower intensity running can require a mixture of carbohydrate, protein [[Protein]] and fat. This tends to occur at ultramarathon distances.
* '''Heat.''' Higher temperatures make digestion harder, possibly because the blood is drawn to the surface of the skin for cooling. Nausea on hot runs is more common than cooler conditions.
* '''Individuality.''' Some runners have the ability to digest a wide range of foods, where others struggle. It is important to learn what works for you.
==Suggested Fueling==
* For runs of an hour or less, most runners do not require fueling. In hot conditions, some water may help. Follow [[Nutrient Timing]] post-run.
* For runs of one to four hours, try simple carbohydrates or a carbohydrate/protein [[Protein]] mix.
** Sports drinks can work well, but different drinks work for different people. I get on well with Gatorade (it's cheap), but other people have digestive distress from it. If Gatorade does not work, try a drink with less sugar and more [[Maltodextrin]]. An example would be [http://www.hammernutrition.com/products/heed-sports-drink.he.html Hammer Heed]. The problem with sports drink is that on races you have few options, and the drinks are often mixed inconsistently. On marathons, it's common to get dilute, colored water most of the time, and occasionally a cup of overly concentrated syrup.
** Adding protein [[Protein]] to carbohydrate can be done by simply adding Whey protein [[Protein]] to your favorite drink, or buying a premixed formula like [http://www.accelsport.com/product-info/Accelerade.html Accelerade]. ** Gel packs are a great source of portable fuel. Most are concentrated glucose polymers which are easy to digest, but personal preferences for different gels vary a lot. I get on well with most gels, though I prefer [http://www.guenergy.com/ Gu] or [http://www.accelsport.com/product-info/Accel_Gel.html Accel]. I find Gu is the easiest to digest of the gels I've tried, and Accel provides added protein[[Protein]]. The only gel I dislike is Cliff Shots, which are made with brown rice syrup that is bitter and does not settle as well as other gels. Also see [[How to eat a Gel]] and [[When to eat Energy Gels in the Marathon]].
* For runs longer than four hours, try solid food. I would suggest starting with simpler solid fuels such as candy (M&Ms are a personal favorite) or crackers. See [[Fueling in an Ultra]] for more details.
* I find that for even 100+ mile runs, that [[Fellrnr's Go Juice]] is all I need, but I am running these distances at a higher intensity than many runners.
