Some practical wisdom on endurance sports nutrition from the book is "Endurance Sports Nutrition", reprinted with permission by Human Kinetics. 

"You are responsible for experimenting in training (before the actual event or race) to discover and build a repertoire of acceptable foods and drinks, and any other supplements, that you will use to meet your fluid, energy, and electrolyte needs during long-distance events and races. You must figure out the basics—what and how much you need to eat and drink and when you need to eat and drink it. Don’t neglect to put your strategies to the test in various weather conditions at your intended race pace or intensity.

• The only way that drinking and eating on the move become automatic on the day of the event or race is by practicing beforehand. Aim to be consistent and stick with what you know. When your favorite or old standby is no longer working, however, you must be willing to try something new. If you’re contemplating tackling ultralength challenges, you first need to establish smart drinking and refueling habits in longdistance events and races.
• Consider how your body processes foods during exercise. Blood flow to the gastrointestinal tract falls as your pace or intensity increases, making it harder to digest and absorb foods that you take in. In addition, your ability to consume and absorb calories when running (because of significant jostling of the stomach) is far less (by as much as 50 percent) than when cycling. Rely on simple carbohydrates during high-intensity efforts or when you need a rapid energy boost. Choose electrolyte replacement drinks, energy gels (take with water) and sport chews, glucose tablets, and  if tolerated, soda or juice. During longer efforts of moderate intensity, add  solid foods and high-calorie liquid drinks to boost your calorie intake and your spirits.
• Refuel frequently instead of eating a large quantity at any one time, which diverts blood away from your working muscles. In other words, spread your hourly energy needs over 15- to 20-minute increments. Don’t try to cram it all down on the hour mark. The best sports drinks, high-calorie liquid drinks, energy gels, and energy bars for you are the ones that go down and stay down.
• Hitting the wall means that you have essentially depleted your muscle glycogen stores. Your legs (and other major muscle groups) have gone on strike, even though you may have been consuming adequate fluids and calories. Your training, or lack thereof, improper pacing, and general fatigue can contribute to this phenomenon. You will often be able to continue and finish, albeit not with the desired performance.
• Bonking, when the body completely shuts down because of a severe drop in blood sugar, is a much more serious situation. The glycogen stored in muscles and the liver is essentially gone. Muscles and, more important, the brain are not receiving sufficient fuel. If left untreated, you may become increasingly irritable, confused, and disoriented. You could find yourself sitting or lying down and could possibly lapse into a coma. Stop whatever activity you were engaged in and boost your blood sugar by consuming readily absorbable carbohydrates, such as sports drinks, energy gels, soda, fruit juice, or glucose tablets, if available. Seek or ask for medical attention if necessary.
• The best way to avoid bonking is to create a calorie buffer. Liquid calories in the form of electrolyte replacement drinks and high-energy liquid products are favored because they tend to be well tolerated and require less effort to get down than solid foods do. Large male endurance athletes often have to consciously work to consume enough calories (for example, as much as 500 calories per hour of prolonged cycling as compared to 300 calories per hour for smaller female athletes) to stay in energy balance.
• Athletes who struggle with sensitive stomachs and other gastrointestinal problems are advised to learn beforehand what sports drink will be served during races and organized events. They can then train with that product or, if they will have access to water, carry their own acceptable powdered sports drink in premeasured baggies and reconstitute it along the way.
• The less fit you are, the fewer shortcuts you can take. Knowing what you can survive on and still perform well with comes with experience. If you are less fit or less efficient (a novice rider or trail runner, for example), you need to drink and eat on a regular schedule. Set your watch or bike computer and train yourself to drink every 15 to 20 minutes and refuel every 30 to 60 minutes to keep pace with the energy that you’re expending."

In the Massachusetts Institute of Technology's Chemistry of Sports course, they "... will be focusing on three sports, swimming, cycling and running. There will be two components to the seminar, a classroom and a laboratory. The classroom component will introduce the students to the chemistry of their own biological system. Since we are looking at swimming, running and cycling as our sample sports, we will apply the classroom knowledge to complete a triathlon.

What do you in the couple of weeks before a race?  Taper?  Test out nutritional intake and timing?

If this is your first race, your mind is likely racing, pardon the pun.  If not your first race, your over your first time jitters and just want to have a better race, faster time, or move up in distance.

John Mora published Triathlon 101 for those new to the sport and those wishing to get an edge in their training and in their next race.  In this 2nd edition of Triathlon 101, you'll find topics such as:

- Choose the best equipment for your goals, terrain, and budget.
- Create your own triathlon program for various distances and events.
- Know how, when, and what to eat and drink when training or competing.
- Prevent overtraining and recover from common injuries.
- Swim and navigate in open water.
- Smoothly and quickly transition from one leg of the

Most everyone has heard of the Iditarod - the famous 1100 dog mushing race from Anchorage to Nome Alaska.  I recently returned from Alaska where I learned of the "Iditarod Trail Invitational", tagged the longest winter ultra race in the world.  You have two routes you can follow, a 350 mile and the original 1100 miler.  The main difference are the modes of transportation.  You can race on bike, snowshoe or on foot. And it's held in March where you it can be 30 degrees below zero with blistering winds.  There are sometimes days between rest cabins or villages so you have to carry a sleeping bag and food with you.  Visit the website here to learn more about it and read some of the competitor's blogs.

How about the "Great Divide Race" which follows the US Continental Divide for  2,490 miles of cycling?

How about a Deca IronMan with a 24 mile swim, 1120 mile bike and a 262 mile run?  Here's their website.

Having never attempted one but from what I can gather, finishing depends a great deal on your mental fortitude; how tired you feel, how exhausted you are, and how the cold and hot plays games with your mind.

Assuming a high level of fitness and training, part of these finishes might be determined by nutrition - have you practiced your nutritional in take on road and in all sorts of weather.  Which leads me to this excerpt reprinted with permission by Human Kinetics.  The book is "Endurance Sports Nutrition", by Suzanne Girard Eberle.

"The biggest danger with multiday rides, runs, treks and tours, cycling classics, sports camps, and climbing expeditions is incomplete recovery—