Nutrition

Body Basics

The human body can absorb around 300 calories per hour. It can also absorb about 1.5litres of water an hour. These are important numbers to remember if you want to take part in adventure sports.

If we consume more calories than 300, our body will not absorb it, likewise, if we consume more than 1.5L of water our body will not absorb it all. (Actually consuming large quantities of water is very dangerous and can lead to death)

Unfortunatley though, our body can consume far more than it can absorb.

In an hour of good trail-running, our body can easily burn of 6-700 calories and if the conditions are hot and humid we can easily sweat out 2-3 litres of fluids.

You don't need to be a rocket-scientist to realize that us humans have a serious problem when it comes to sustained effort in demanding conditions.

For this reason it is essential that we take some time out to learn about our best bit of kit - our body, and pay attention to its needs and wants.

If we exercise in hot conditions for over three hours, it is impossible for us not to be experiencing a calorie deficit and be slightly dehydrated, and this is if we do EVERYTHING right. Very few people fuel and hydrate themselves correctly for races.

Calorie Deficit

Actually this isn't as attractive as it sounds. At the end of a race, you may look and feel thinner, but this is fluid loss, not fat loss. The chances of you burning any significant amounts of fat in a event, no matter how long, is very small. You can only lose fat in small amounts and after sustained exercise, which lasts for days, weeks or months. Whatever anyone tells you about fat-burning is rubbish, if it doesn't involve a significant expenditure of time and energy.

The body has a store of glycogen which it uses to power our muscles. When the muscles start moving, they start burning glycogen. An average person has a glycogen store of less than 50 minutes. Just enough energy to get you out of trouble. As an athlete, if you train hard and carbo-load, you could probably push your glycogen store up over the hour mark, but not much more. This is why on a 10k race, you don't need to eat, or in games like football or rugby, they don't play longer than 45 minutes per half. After about fifty minutes your body will start asking where the rest of the energy is going to come from. In a perfect world the body would start burning the thousands of calories sitting around our waist or on our arse, but unfortunately it doesn't work like that. This energy is "last-resort" energy, designed to keep us alive when the shit really hits the fan and not when we decide to pay an entry fee and run up a hill. Our bodies can see right through this and don't fall for it. Fat is an important commodity on the body and is not given up so easily.

Instead the body asks two things;

Please stop, because there's no more readily available energy
Please give me more fuel or I will start to look around for other things to convert into energy

This is where the theory about taking a gel just before the hour mark comes from. Which is a great thing to do. However, from what we've already learnt, we know that by the time we take that first "race" gel our body could easily have burnt 700 calories. So, taking a gel, which contains just 125 Calories, insn't going to cut it. The body is going to want more! On a high impact race, you really should be trying to take as many gels as you can stomach, if you want to sustain your energy levels. On longer races, you need to be consuming some other kind of carb as well.

The body loves carbs. They're the easiest way to make energy, once our glycogen levels have been depleted. This is why gels are made of carbs.

As most people don't even take one gel an hour, the body begins to look around for ways to make energy. Fat is much too important to the body, so it chooses to break down protein instead. Our muscles are made of protein and as we continue to go further and further our muscles begin to break-down to keep the body moving. This is why after a big event involving many miles or hours, our muscles feel totally destroyed, because effectively, we threw them on the fire to keep moving!

So, the inescapeable fact is that if you do long, sustained events, you can't hope to keep your body properly fueled. However, you should at least try to meet the body's requirements, which is 300 calories per hour, every hour, as long as you are moving. Which basically means eating little things as often as possible. Gummy-bears, jelly-babies, trail-mix, candy, flat coke can all help to keep the calories up.

On a multi-day event like The LMX or KMX you should also eat like a horse at the campsite as well. little and often is best. Maybe two or three freeze-dried meals while hanging around camp.

On the last LMX, one of the competitor's heart-rate monitor told him that he'd burnt 6500calories on the first day! In race conditions, these kind of calories need to be replenished. Racing is not a weight loss program!

Water

As we said before, the body can only absorb 1.5L of water an hour, but can flush out much more by sweating. This can lead to all kinds of problems, especially in Hong Kong. To get a sense of how important it is to drink enough, it's good to have an idea of where all the water is going.

When we exercise, the muscles produce heat as a by-product. Our temperature variation for life is very small. An average person has a body temperature of 37.5'C. If the temperature raises just a few degrees then it can have drastic consequence and can easily cause permanet damage or death. Having such a small "window" for life, the body is pre-occupied with keeping itself cool. It's a common mistake that when we do any kind of exercise in extreme cold, we prepare alot. Yet, when we exercise in extreme heat we barely give it any thought, other than a having an extra drink and applying sun-cream. Heat can kill you much quicker than cold. Once your body loses its ability to cool itself it can literally boil your brains in the same time it takes to boil an egg. Compare this to dying of cold, which can take hours and sometimes days!

To cool itself down, the body loses heat by flushing itself with liquid (sweat). Heat is taken away from the muscles and dissipated into the environment around us by evaporating off the skin. Leaving just the salt behind. This is why we get huge salt rings on our clothes, or our skin tastes salty after a run.

This method of cooling is very efficient, however, some weather conditions can work against this system. In hot, humid climates the sweat has nowhere to go, so it sits on our skin, waiting to evaporate. The body still needs to keep the muscles cool, so it flushes them with more and more water, which still has nowhere to escape, as the atomosphere is saturated. In a desperate attempt to keep itself cool, the body will flush (or sweat) as much liquid as it can. This is why on very hot days our body can easily lose 3L in an hour. We can't hope to keep up with this and the body can't physically absorb as much as it is sweating, so eventually we become dehydrated.

On hot styfling days, when there is no breeze, our body is working overtime to keep us within safe heating levels, and when we turn a corner and experience a breeze, it's not just the breeze itself that feels cool, but the sweat evaporating off our body allowing the heat to be dissipated into the environment that is giving us the cooling effect.

Dehydration

Becoming dehydrated is very dangerous. At just 2% dehydration our body has lost upto 20% of its performance and over 11% there's a high chance of death!

It is important to know the signs and symptoms of dehydration. Dehydration is serious, and even mild cases should be immediately addressed. Low fluid levels can affect your mind’s ability to concentrate, reduces energy levels, and may prevent organs from functioning efficiently.

Percentage of body water lost and your body’s reaction

0 to 1% thirst
2 to 5% dry mouth, flushed skin, fatigue, headache, impaired physical performance
6% increased body temperature, increased breathing and pulse rate
8% dizziness, increased weakness and laboured breathing with exercise
10% muscle spasms, swollen tongue, delirium
11+% poor blood circulation, decreased kidney function, organ failures, death

In a dehydrated state, the body is unable to cool itself; this can lead to heat exhaustion and possibly heat stroke. Dehydration also leads to muscle fatigue and a loss of coordination. Therefore, even small amounts of dehydration can hinder your athletic performance.
It is common to hear people say "I don't need that much water, I'm like a camel" This is a very dangerous attitude because, even though it is possible to train your body to adapt to using less water, no-one is like a camel, as no human has the ability to take on huge quantities of water in one sitting, or rapidly metabolize fat into energy.

For the sake of carrying just a litre of extra water, you risk destroying all the good work you've accomplished in your training, your long term health and even death.

To convince yourself of this, just talk to someone who has experienced severe heat stroke, brought on by dehydration, and they all will tell you about the long road to recovery.

Everyone of the people who Adventure Unlimited have dealt with, who have suffered heat stroke have been very fit, experienced athletes. Dehyration is not a problem suffered exclusively by the inexperienced. There's an obvious reason for this, as we become more experienced and fitter, we are able to extend our runs and push ourselves harder and thus move our body into more dangerous levels of dehydration. Usually, we are unaware that our training pattern is dangerous until it's too late and we have tipped over the edge.

The best way to avoid dehydration during runs are:

To drink when you are thirsty

Drink when you are not thirsty

And all the times inbetween

Drinking small amounts often, will ensure that you are absorbing as much water as your body will physically allow. In hot conditions, if you are going to run for over an hour or more, running with just a small hand-held bottle is not adviseable and could ruin all your good-work.

As you can not predict 100% the trail/weather/your body conditions, you should always carry as much water as you can in case of an emergency. At worse it will make you a stronger runner, because you are carrying a little more weight, at best it could save your life!

Conclusions

Understand the limitations of your body and concentrate on meeting its requirements every hour that passes, to keep you moving.

Every Hour

300 calories in - Upto 700 calories out

1L to 1.5L in - Upto 3L out

Simple!

LMX-KMX Recommends

LMX-KMX RACE

Hong Kong's Only Self-Supported, Trail-Race Series