Hypothermia: Definition, Cause and Prevention by Robert Finlay of Kayak Lake Mead
This article is about hypothermia and is directed primary to YOU as a kayaker in regard to paddling in cold
water and what you can do to prevent it, and also if need be, to recover and survive from it. This knowledge
is a mandatory kayak skill for both you and those you paddle with.
I have been an adventurer for a long time (resume). I have seen the effects of the cold in others and in myself.
I have seen severe hypothermia in others and I have suffered from severe hypothermia. I have learned from
experience and study the causes, the preventions, the treatments and the recoveries.
Side bar for adventure racers: The best treatment for hypothermia is to prevent it from happening in the
first place. But, if you are an adventure racer that simple statement is going to be hard to put into practice.
Inevitably, for several reasons, you are going to get hypothermia. One, the decisions you make in regard to
weight versus speed will often cause you go to light without the right gear. Two, because your body fat to
weight ratio is probably very low you are more susceptible to start with. And three, you are racing and
therefore pushing hard which can cause all sorts of undesirable consequences including hypothermia.
This article on hypothermia will give you good working definitions and explanations of hypothermia and how to prevent it. My other two articles on hypothermia will help you see it coming and how you can treat it AND explain what I've learned as an outdoor adventurer on how you can SELF-RECOVER from hypothermia.
What is hypothermia:
"Hypo" means under. "Therm" is a unit of heat. The normal core temperature for you body is 98.6 degrees F.
"Core temperature" means the temperature of internal body organs, particularly the heart, brain, lungs,
kidneys, stomach, and intestines.
An abnormally low core temperature is the condition of hypothermia. In this condition normal muscular and
mental abilities are impaired. If the condition continues to deteriorate it will lead to death.
What causes hypothermia:
Hypothermia IS CAUSED by 1) sudden exposure to cold water or CAN BE CAUSED by 2) prolonged
exposure to the cold conditions of temperature, water, and wind or by 3) or a very slow and prolonged period
of cold conditions AND prolonged fatigue, exhaustion, and lack of food which is not uncommon among
adventure racers. In this last case shivering may never be a symptom, but there will be plenty of other signs.
When heat loss exceeds heat production and heat retention; hypothermia is the result.
Let me say it again: When HEAT LOSS is greater than HEAT RETENTION and HEAT PRODUCTION...
Hypothermia is the Result
Heat is lost by the body to the conditions of the environment by...
Radiation (cold condition - temperature of the air)
This is when the EXPOSED surface area of your skin is warmer than the surrounding air. This occurs in all
air that is less than 96.8 degrees F and from all skin that is exposed.
So, wear clothes, but remember YOU will lose twice the amount of heat from your head as from the rest of
your body, that is why head gear is SO important. Thus the old adage, "if your hands or feet are cold, put on
Conduction (cold conditions - temperature and water)
Heat is conducted from direct contact between your warm body and colder objects. The more dense the
object the greater the ability to conduct heat. Heat is conducted from your exposed skin or through clothes; to
the ground, to the air, to the kayak seat, from your feet to shoes to kayak hull, from your hands to gloves to
paddles shaft, etc.
Since water is much more dense than air, heat will be conducted away from your body much faster (probably
at least 5 times faster, but some sources quote the rate as 25 times faster) in water than in air. Heat is
conducted from the body through WET clothes much faster than through dry clothes. That is why the
statement, "to stay dry is to stay alive".
So, you must stay dry. Have the proper rain gear, storm gear, and spare dry clothes (that you do not allow to
Convection (cold condition - primarily wind)
Heat will be lost to moving mediums, the denser and faster the moving mediums the faster the heat loss. You
will lose heat more quickly in fast current than in still water. You will lose heat faster the faster the air is
moving, this is 'wind chill'. This is the importance of wearing something to 'break the wind', such as a paddle
jacket, dry top, etc.
This heat loss is due to your body's processes of converting water from liquid to gas.
Perspiration is the evaporative process your body uses to cool itself during exercise. Insensible Perspiration is
the evaporative process your body uses to maintain 70% humidity next to skin, which can be a lot of water
particularly in a cold, dry environment. Respiration is the evaporative process that occurs when air is heated as
it enters the lungs and is exhaled with moisture content from your body.
Evaporation processes are natural functions. There is nothing you can do to retain heat in regard to
evaporation. But you can breath through a light covering over the nose and mouth to pre-warm the air that you
Sidebar: Knowing about the constant loss of water due to evaporation, it is important to stay hydrated.
Retaining your heat and producing heat are how you prevent hypothermia.
More on heat retention:
There are FOUR ways to increase your body's ability to retain heat while kayaking.
1) Practice being in the cold. That's right, acclimate and become used to physical exertion in the cold. The
body does a wonderful job of adapting to different conditions. If you spend all day and every day in the warm
office, you are not going to be physically prepared for a vacation of long cold, wet days of kayaking.
By spending a few hours outside in the cold a few times a week, you can prepare yourself. This does not take
a big science project. For instance, you'll notice when your hands, without gloves for say 20 minutes, are not
as cold after several weeks of 'practice' as they were when you first started.
Adventure race team sidebar: Let's say, it is June, you are from southern California and you are going to
Poland for an expedition race in the Fall. Consider training at higher elevations at night during the summer, not
for the altitude (which won't hurt anyway) but for the cold. Also, consider arriving in Poland a week ahead
of the race start and hanging out in shorts and short sleeves a little bit.
2) Put on more body fat. Body fat is insulation. Insulation will prevent conductive heat loss. Fat, by the way,
is not necessarily bad for you. In fact, your body needs certain fats for health. So, be wise about your
nutrition, your diet, and your training.
3) Make your rescues proficient. Plan on being in the water! This means consider how long you might be in
the water should you capsize. And do not assume that you are not going to capsize. That kind of decision is
what causes hypothermia.
And if you have a good kayak roll, do not assume that you will be able to roll in cold water. The effects of
fatigue, exhaustion, and the shock of cold water immersion will likely cause you to miss.
And if you are not real proficient at wet exits and re-entries practice some more. Again, the shock of cold
water immersion and fatigue probably will cause a longer time than usual to sort out the rescue (getting back
in the kayak). The less time in the water the less time for the rapid heat loss of cold water conduction.
4) Wear the right clothes for the water, which means dress for the water temperature and not the air
temperature. Any water colder than 96.8 degrees F can cause hypothermia!
Again, plan on being in the water and do not assume you won't capsize.
And consider, given the possible conditions, how wet are you going to get while kayaking. Kayaking with a
light wind is going to be a lot dryer than kayaking into 20 mph winds and the resulting waves.
But do not assume that the weather is not going to change. This is another decision which causes hypothermia.
The only way to know what clothes to wear for the water temperature is through practice. Everyone is
different with different abilities to ward off the causes of hypothermia.
And there are two ways to retain heat while beached up.
1) Get in your dry non-paddling clothes (that you have brought in a dry bag). These clothes you never get wet
and never paddle in.
2) Get inside your sleeping bag and use an insulating pad between your sleeping bag and the ground.
There are THREE ways to produce heat to prevent hypothermia.
1) The body produces heat by the digestion and utilization of food. This is the main fuel source for the body's
furnace. While in cold conditions you have got to eat to stay warm. And to digest the food you have got to
stay hydrated. You can not digest food without water.
A little about food. Carbohydrates, with 5 calories/gram are quickly released into blood stream for sudden brief
heat surge. Carbs are the best to use for quick energy intake especially for mild cases of hypothermia. Proteins, with 5 calories/gram are slowly digested and release heat over a longer period of time. Fats, with 9
calories/gram are slowly released but are good because they release heat over a long period, but it takes more
energy and water to digest fats.
2) Heat is also produced during exercise, in our case paddling. But, you need to remain fueled to continue
paddling. Shivering is a natural mechanism that creates involuntary exercise and produces heat. But, if you are shivering, you are losing to hypothermia. You need to retain or produce more heat.
3) The body can also gain heat from external sources. These can include but are not limited to warm food and
drink, chemical heat pads, fire, and of course the sun.
While paddling you can drink warm liquids that you have already prepared from a thermos. You can eat warm
food that you have already prepared from aluminum foil or in the case of freeze dried foods, from the
container they come in. Before you paddle, prepare a freeze dried meal with boiling water in its container,
leave a spoon in it, and it's ready to eat and warm when you need it.
And while paddling you can utilize chemical heat pads by placing them inside your paddling jacket or pants
(however, don't place them directly against the skin).
If you have beached up you can build an emergency fire, prepare warm food and drink, and use heat pads.