Few races push competitors to their physical, mental and spiritual limits like the Ironman Triathlon World Championships in Hawaii. The geography, the duration of the race, the environmental conditions and the sheer number of participants make this annual event the ultimate goal for many athletes. With all the effort that has been put into earning a spot in Kona, no one wants to end his or her day early, but the Hawaiian gods may have ordained that you are going to face an obstacle or two in your quest to conquer the course.

The bonk

Nutrition is the fourth, and often most important, discipline in Ironman racing. No one enters the race planning to bonk, but it happens. It starts with a lightheaded feeling and increasing difficulty in concentrating on the race. It continues with waves of disorientation and fatigue, and then the body starts telling you that it is going to slow down. You start to fantasize about sugary and fatty foods. Where did things go wrong?

Kona offers a unique race environment that can wreak havoc with your nutrition. Don't try to push through the bonk - the gods will win. Start by slowing your pace a little and try to consume carbohydrates. It is important to take these carbs regularly, but not to gorge. If you inundate your system with an overload of carbohydrates, you may taste them again on their way back up. Eat frequently but in small portions, allowing your body to absorb the calories before more come barreling down your throat.

To ward off an impending bonk, go for liquids and gels first to allow your body to quickly absorb the carbs and get your mind and body back on track. Follow those with solid food if you can. Walk through aid stations, drinking and eating. Don't worry about lost seconds in the aid stations - refueling is your most important goal when a bonk is imminent. When you start to feel good again, keep putting the carbs in. Ironman is a long event and you can recover from a bonk, but you must be smart and proactive about your nutrition.

Environmental conditions

The intense heat, blistering winds and the sting and chop of the salt water challenge the fittest and most dedicated athletes in the world. Make sure that your body is able to sweat by keeping the water stores topped up. Stay hydrated the week before the race. Drinking juices, water and sports drinks will allow your cells to absorb the necessary water and electrolytes to help you keep cool on race day. During the race, make sure that you are replacing your fluids, especially on the bike, when you may not feel that you are sweating much. Wearing lighter colors and a white hat (that you can put ice in) will also help you contend with the heat.

If the gods don't get you with heat, then they may throw wind at you on the bike. But remember, everyone on the course is facing the same conditions. Stay positive - the power of self-affirmation cannot be underestimated. Also, maintain a strong, sleek aero position as you ride through the wind. Keep your cadence up and focus on efficient pedal strokes, rather than trying to power through the wind with a lower, strength-based cadence.

The third, and often overlooked, environmental factor is the salt water. This can be a real challenge for those who have not swum in salt water before. The taste can be discomforting and cause thirst, and some athletes report feeling seasick. To get used to the idea of having salt water in your mouth, add table salt to tap water at home and rinse your mouth with it. When you start the bike, try drinking more water initially and less electrolyte-carbo drink.

The swim

The four most common obstacles people face in the swim are: losing their goggles, getting hit by other competitors, being unable to navigate and feeling trapped or claustrophobic. Stay calm and deal with any obstacles as they arise. If your goggles get knocked off, continue trying to swim so you don't get run over from behind, then find some open water to put them back on. If you get hit, try to move away, but don't tense up. Being tense costs too much energy and will negatively affect your swim. Be malleable in the water.

If you feel trapped, pop up your head and look for open water. Once you have some clear space, settle into your rhythm and use the open-water sighting routine you have practiced in workouts. Find a pair of feet that are headed in the right direction and hook on for the ride. Swimming in a draft uses less energy, but if you don't like the idea of being surrounded by people, relax and move to the side of the pack.

Overdoing it the week before

Hawaii would probably be in the top 10 of most people's lists for the most beautiful holiday destinations in the world. The fact that there happens to be a great race there is a bonus. If you are using the race as a vacation, then there is no need to read this section. However, if you are using your vacation to race, then make sure that you have your priorities straight. Don't go sightseeing. Do not lie out in the sun (you will get a great tan during the race). Do not walk around shopping. Follow your taper and sit on your butt. Don't be a tourist, be a racer.

Save your race for race day. As you enter your taper, resist the urge to fit in any last-minute long training sessions. You will see athletes far out on the Queen K highway the week before the race, dueling with other age groupers from around the world. It is a hard temptation to resist, but remember, when you get back home, the only race that will be important to you is the one that comes with an official set of results. There are no fitness gains to be made two weeks out from the race, and sessions should only be for tuning-up what   you have already done.

Ironman Hawaii is often referred to as the true test of an Ironman athlete. Many athletes who have had success around the world cannot conquer the island. But for most people, the day will end with a dramatic run along Alii Drive. As in life, there will be obstacles that will be placed in your path, but the true test of resolve is in how these obstacles are approached and overcome.