Randall J. Brown, MHS, PT
From time to time one might ask themself: Would I rather freeze
to death or roast to death? My answer seems to vary predictably
with the season. In the winter, the last thing I want to do is
to freeze to death. Read on and you'll understand why. You'll
also learn how to protect yourself from the cold while you're
running outside. In short, this article may help you to survive
if you don't know Jack.... Jack Frost, that is.
:Humans as Homeotherm:
humans must maintain our body's core temperature within relatively
narrow limits in order to stay alive (75-105 deg. F). Your intelligent
body wants to maintain its core temperature as close to your 98.6F
(37C) set point as it can. Therefore, when your body is confronted
with cold temperatures, it will shunt blood towards the core and
away from the extremities by constricting blood vessels (vasoconstriction)
in your limbs. Your body produces heat internally in several forms:
biochemical reactions (basal metabolism), by shivering, and by
You Say Hypothermia?
:The Dangers of Getting too Cold:
know from experience that moderately cold environmental temperatures
enhance performance. Severely cold temperatures can adversely
effect our performance though, and prolonged exposure to the cold
can be deadly if hypothermia (the lowering of our core temperature)
occurs. Unlike acclimatization to the heat, the human body has
no adaptive ability to the cold except for mental tolerance. Risk
factors include people with low body fat, poor nutrition, dehydration,
and alcohol use. Hypothermia is categorized as mild, moderate
- Core 90-97F - uncontrollable shivering; decreased fine motor
skills and cognitive function; amnesia
- Core 85-89F - shivering stops; irrational behavior; grossly
uncoordinated movements; somnolence
- Core below 85F - no pain response; loss of reflexes; coma;
lowest adult hypothermia survival is 60.8F
aware that hypothermia can set in rapidly after you stop running.
Your heat production engine has stopped but the loss remains high.
It is therefore important to find shelter and to get into some
dry clothes as soon as possible.
Hazards of Frostbite - What Bit Me?
for a moment about a cold wind on you exposed skin and the effects
of vasoconstriction of blood vessels supplying your extremities.
Remember that your body wants to keep its core and vital organs
warm and, when push comes to shove, your torso frankly couldn't
care less about the comfort your hands and feet. The reduced blood
flow to your extremities coupled with very cold temperatures can
lead to actual freezing of your fingers, toes, ears and nose.
Even more alarming, once the area is numb from the cold, you probably
won't even feel the damage as it's occurring. True frostbite is
an irreversible loss of tissue. Let's categorize this cold injury
in two ways:
- termed "frost nip"; it is a reversible condition
involving skin surface only. The skin is numb, waxy and white
but without blisters.
- Deep purple blisters appear. You are in trouble. The bone
may freeze. Amputation may be required.
and cold water immersion followed by freezing have very poor prognoses.
Practices for Running in the Winter Prevention of Cold Injury
:Reducing your heat loss to the environment takes careful judgement.:
your clothing - Resist the temptation to overdress, as excessive
sweating under too many layers may result in your getting really
cold during the run - especially if you have to stop or slow
way down or you find yourself running into a headwind.
fabrics to wear - The best fabrics for cold weather running
are those that have high insulating properties that are not
diminished significantly by wetting. These fabrics include Polypropylene,
wool, wool/synthetic blends, and treated polyesters like Capilene.
The fabric closest to your body should wick moisture away from
your skin. Avoid wearing cotton. It has poor insulating ability,
which decreases even more when it becomes wet.
protection - It is essential that you wear an outer layer of
Gortex or nylon for cold weather running. This includes top,
bottom and hood. Vaseline on any exposed skin is helpful if
it is not severely cold weather.
miscellaneous body parts
a cap! Everyone knows that you can lose a lot of heat through
radiation from your head. Well-vented ski goggles can be worn.
Be careful of wearing contact lenses in extremely cold weather
- they can freeze to your eyeball.
gloves and maybe Gortex or nylon mittens are important to protect
wearing two pairs of socks - an inner polypropylene pair and
an outer wool pair. Size your winter running shoes appropriately.
trunk cooling leads to vasoconstriction in your extremities,
you should adequately insulate your trunk in order to help keep
your hands and feet warm.
may want to wear some briefs with strategically placed insulation
to maintain comfort during and after your cold weather outing.
Getting Wet - Soaked clothing from things like rain showers
and nearly frozen rivers can lead to some serious problems.
Gortex will protect you from rain. Avoid bodies of cold water
- especially if you're clumsy.
wind chill - Like considering the humidity and temperature for
a summer run, you must account for the wind and temperature
for running in the winter. This refers to both natural wind
and the air movement created if you are running fast.
properly - As you probably know, it's hard to warm up when you're
freezing cold. The key is to do your stretching while you're
inside, then to wear heavier clothing outside until you warm
up, at which time you shed your layers down to the right amount
for the current weather conditions.
into the wind on the way out - Try to avoid running into a headwind
on your way home when you are sweaty and tired.
hydrated - Although it's cold, you will continue to sweat while
you're exercising. Under several layers of clothing, you may
not realize how much you are sweating. Also, in very cold weather
the humidity approaches zero, and large amounts of fluid are
lost through exhaled vapor.
nourished - During long runs in the winter, plan on eating snacks
at regular intervals. Good nutrition is necessary for prolonged
medical help for hypothermia and frostbite - Get to a hospital
if you become more than mildly hypothermic.
for asthmatics - When the temperature differential between the
ambient air and our lungs is large (over 100 degrees F), the
air entering the lungs cannot be fully warmed or humidified.
This can cause a reactive bronchospasm even in normal subjects.
Asthmatics should be particularly aware of this risk. Bronchodilators
can be helpful when used prophylactically before your run.
doing his best to stay warm while working as a physical therapist
at the University of Virginia in Charlottesville, Randy has been
both a competitive and recreational runner since 1974. He competed
through high school in Chico, California, and college at the U.S.
Merchant Marine Academy in Kings Point, NY, and at the corporate
level for General Electric. He has coached cross country at the
College of Charleston, was a 3-term president of the Charleston
Running Club, and the company physical therapist for the Charleston
Ballet Theatre. Randy is also a licensed massage therapist and
a former engineer.