Having thought about this for a few days, and seen some interesting examples of nutrition over long day efforts in the past few years, I thought it might be time to write a little about my strategy for long drawn out efforts.
I should make it clear that this is only my opinion, and that it works for me in the UK, I haven't actually tested it in the Alps, or across subcontinental deserts, or on K2. Its not particularly scientific, and I'm not going to start going into calorific counts, but that is something that you should think about if you are going a step further into higher performance nutrition.
So. The laymans thoughts on long day out nutrition-
First, lets describe a long day out. More than 5 hours.
If you're running for less than an hour, you won't need water unless its ridiculously hot.
If you're running for more than an hour, you will need something to drink- ideally something with electrolytes in.
If you're running for more than 3 hours you might need some kind of sugary food.
If you're running for 4 hours and over, especially 6 hours and over, you probably should be thinking about planning your food and feeding times. Its this catagory that I'm going to talk about today.
The key to it all is just like that of being thirsty. If you wait until you're thirsty til you drink- its too late. Equally, if you wait until you're hungry- its getting a little too late as well. So, eat and drink little, but often.
Get as many decent slow burning calories into you at the beginning of the day. If you don't "do" breakfast. Learn to "do" it. It is the single most important meal of the day, even more so on a long drawn out day. Get a decent energetic base, and top it up throughout the day. If you don't have that, don't bother reading any further.
As Dan John said, if you want to know about nutrition but don't eat breakfast, don't talk to me.
I tend to eat muesli or porridge, or something of that ilk with dried fruit to keep my energy burning slowly for as long as possible. If its going to be a long day, I'll increase the portion size. Not so large that I feel uncomfortable eating it, but large enough that it is going to give me that extra endurance. (ie. one extra spoonful of the oats when dry)
Water- oh so important. Obviously you can't run for a long long time if you are dehydrated. Your muscles are approx 75% water. The fascia between them is also highly reliant on being hydrated to a decent degree. Once things start getting dry bad things happen. Keep drinking.
However. You may have heard of Hypotranemia. Basically it can happen when you drink too much water. You dilute your body so much that it can't cope and basically drown yourself. This can happen because the minerals in your body become too dilute and can no longer cope- the way to stop this from happening- (and incidentally also decrease the likihood of cramp) is to add electrolyte to the water.
I tend to use High 5 Zero or the Nuun tablets. They are excellent as they replace lost salts, potassium, calcium and other things that you're body needs in small doses to keep working properly- but loses on a big scale through sweat production.
For example- did you know that muscle contraction relies on calcium within the muscles. If the calcium is not there than the muscles cannot contract. It will need to be replaced as you sweat all the goodness out of you.
Use electrolyte. Its not Snake Oil.
As for drinks with carbohydrate in, thats an interesting one. I did a few races drinking a carb mix drink and eating food throughout- about 12 hours or so. By 8 hours in both me and my team mate were getting horrendous gut cramp and feeling pretty damn awful. In hindsight, it was because we were ingesting far too much carbohydrate for the body to cope with.
Apparently the gut processes about 60 mg of Carbohydrate per hour. Any more than that and it gets backed up in the digestive system. If you're loading it with 100 per hour for 8 hours, thats an awful lot of carbs that are waiting to be digested by the end of 8 hours, and although they may be there in the system, you are probably still feeling hungry and need to eat more. Wierd.
So, if you are insistent that you want a carb energy drink as well as eating food, be careful of just how many carbs you are loading in on yourself hour after hour. You don't want cramps 3/4 of the way through the day.
The alternative is to just drink, or just eat- and drink electrolyte. The problem with just drinking is much the same as "eating", or should I say, consuming, energy gels.
Energy Gels are sold as the be all and end all of sports nutrition. Yes, they have their place, and yes, they work to a point, but you need to get used to them if you are using them for a long period of time. The TdF guys use them, but their efforts are for a max of about 5 hours a day, certainly not up in the 10-17 hour bracket. I know that some alpinists use them, and all power to their arm, but I have a couple of issues with them.
The massive sugar spike and crash is not fun to deal with, unless you are on the last burst of the day. 1 gel gives a boost that lasts maybe 20 mins, then you need to take another one, and another etc, to keep the "rush" going. Should you try to do this over 15 hours, just eating gels, the stomach has no actual food to digest, it feels hungry. Ok, you are loading a lot of sugar and craziness into it, but it doesn't FEEL like food. Unless you are very used to this, its not going to be good, and you're going to bonk massively. Not through lack of energy, but through hunger. You need real food as well as energy gels.
I carry gels, but only a couple, for dire emergencies, or for a kick to get me through to the end of a race. The pick-me-up is massive, and as long as you can finish - or eat real food before you crash, happy days.
So, what to eat?
On a long day I tend to go with the principle of eating something every 30 mins. The perennial favourite is Geobars- I tend to calculate for half a geobar every half an hour, though in the recent 15 trigs, I planned for that and ended up with 6 bars left over. By the second half of the day I had eaten my sarnies, and the energy from those was keeping me going and I didn't need the bars so much. Had we been going at a faster pace, I suspect I would have been eating more.
Find a bar- preferably not chocolate covered- they melt and cause a helluva mess- that you can eat pretty much forever without getting sick of it. Use that- and try not to make it a favourite bar, because you will start to see it as race food, and won't eat it at any other time. Added bonus- 1 gel costs between £1-£2, and will last you 20 mins. A box of Geobars costs less than £1.50 and theretically lasts you 5 hours. (yes, there used to be 6 in a box, now there are only 5- scandalous I know, but such is the way of the world).
So thats your core food for the day sorted.
However, you can't just survive on that, lunch, snacks, if you have a box drop or a transition box somewhere, you can stash food in that. But what should you have?
Food that you like to eat- and that will make a decent change from high energy bars. One staple that we always use in a transition box is a loaf of cheap white bread, pre-buttered and put back in its bag. Hit the transition and the first thing you do is rip a hunk off and eat it while getting on with everything else. Sheer genius. Texture and taste is a world away from what you have just been eating, its wonderful and highly recommended.
A lot of people do the same thing with Soreen- pre-buttered etc. Great- but I had a bad experience with it on a race and seriously can no longer even smell the stuff without gagging. If it works, eat it.
A box of salted peanuts is a good idea, even if you have been drinking electrolyte, the extra salt is brilliant, as is the energy from the nuts.
Fruit is an interesting one as it always tends to get squashed. If you can organise it so that it doesn't, at a transition 14 hours into a race, you will be craving something different, and fruit may well be the answer.
If you are carrying sarnies with you, they will probably not end up quite as you put them in your bag. Soggy, squashed and in component parts is the general rule of thumb. I get over this by using pitta bread. I cut them in half and have a different filling in each half, that way you can eat it individually or as a massive energy ball of craziness. Most recently I had one with Jam, one with Nutella and one with just Butter. The one with just butter cannot be overstated in importance. Sometimes, all you want it bread and butter, and it tastes amazing.
However, jam, nutella and butter as a combo was pretty good on top of Winhill last weekend as well.
Other bits and bobs-
I tend to carry an alternative energy bar as well as the geobars as well- something to eat every 5-6 hours or so as a change in taste and texture, yet still keeping the energy up. Current in the pantheon of favourites is the chocolate elevenses bar. I'll carry maybe 2-3 over the course of the day, and they are for ocassions when I just can't face another half of a geobar- and is a bit of a psycological lift for a while as well.
Nuts and dried fruit have their place, as long as they are in something that is easily accessible and doesn't take up room. it must be easily closable as well- so that the contents don't go all over your bag when you've half eaten them.
Thats about it really- but just keep eating. An endurance effort is basically just one long feed.
If you find it difficult to eat and then run, Practice.
If you find it difficult to eat and run at the same time, Practice.
If you are un sure of how much to take, Practice.
If your long endurance effort means anything whatsoever, you won't just practice running/cycling/walking or whatever, you will need to work out your nutrition. That will be the key to success or failure. You can keep going through blisters, pain and lack of preparation if your nutrition is good- but fail to fuel up correctly and you can look forward to failing altogether.