What fuels us?
Lesson 1: Why is glucose important for the body and brain?
October 2014
THE ICEMAN
Wielding the Power of Homeostasis
Scientists are baffled. He should be dead.
Immersed in an ice bath for over an hour, Wim
Hof emerges feeling cold, but otherwise
completely okay. Nicknamed the “Iceman,”
Wim Hof is a Dutch world record holder,
adventurer, and daredevil with the ability to
withstand extreme coldness. He holds the
world record for longest ice bath (1 hour, 13
minutes, and 48 seconds). In 2009, Hof
completed a full marathon above the polar
circle in temperatures close to -20°C (-4°F)
dressed in nothing but sandals and shorts. That same year, Hof also climbed to the top of
Mt. Kilimanjaro, again with just his sandals and shorts.
Wim Hof’s ability to maintain an internal temperature is what allows him to brave such
extreme temperatures. This process by which the body maintains a constant internal state
is called homeostasis. The human body is always maintaining this balance by controlling
our breathing, heart rate, oxygen and carbon dioxide concentrations, blood pressure, blood
glucose levels, body temperature, and much more.
When we find ourselves in a cold environment, our body needs
to increase its temperature to make-up the difference in the
amount of heat the body is losing to the cold air. There are
multiple mechanisms in the body that manage this task. A
central goal of many of them is to encourage glucose
metabolism. Glucose metabolism behaves similar to a car
engine that uses gasoline to do mechanical work but still
becomes very hot in the process. Glucose is metabolized for
cellular work, but heat is still given off while breaking it down.
This is why we get so hot when exercising; the more work our
muscles do from using glucose, the more heat is produced.
Metabolism:
The chemical
processes occurring
within a living cell or
organism to sustain
life. For instance,
the chemical
process involved in
breaking down
glucose provides
cellular energy and
heat as a byproduct.
The human body has the remarkable capacity of keeping its core
temperature constant, somewhere around 37°C (98°F).
However, the body can only regulate body temperature to a certain extent. If a person
enters ice-cold water they begin hyperventilating and gasping for air. (These mechanisms
increase the amount of oxygen and glucose that enter cells to produce heat). In about five to
fifteen minutes, the blood vessels in the arms and legs constrict to divert all energy, heat,
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What fuels us?
Lesson 1: Why is glucose important for the body and brain?
October 2014
and resources to the core organs. Soon after, hypothermia can set in, as a person’s core
body temperature drops below 35°C (95°F).
Wim Hof, the “Iceman,” seems to defy the natural bodily response to extreme cold. Maria
Hopman from the Nijmegan Medical Center in Netherlands has studied Hof’s physiological
responses in an ice bath to more closely make sense of his ability to withstand the cold. Hof
swallows a pill that sits in his stomach and relays temperature readings to the scientists.
While in the ice-bath, Hof is able to control his heart rate and breathing at regular levels.
After 80 minutes in the ice-bath, Hof’s core body temperature barely drops. Looking at
other measures during the test, Maria sees that Hof’s oxygen consumption by his cells
doubles, revealing, that in effect, his energy expenditure doubles. The heat that is generated
from the glucose being metabolized in Hof’s body aids in increasing his core body
temperature. However, Dr. Hopman adds that although increasing his metabolism helps Hof
keep his core temperature relatively constant, there are other pieces of the puzzle that need
be explored.
How does Wim Hof’s body amplify its
metabolism so drastically in response to
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the cold compared to the average person?
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Hof states that he is able to accomplish
his amazing feats by “turning his own
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thermostat up” with his mind. This is
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puzzling to scientists because
mechanisms that maintain homeostasis
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are involuntarily controlled by the
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brainstem. We cannot simply tell our
heart to beat faster or our pores to stop
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sweating. Yet, Wim Hof is not the only
Rest
45 min
80 min
case of a human having the ability to raise
Figure 1: Hof’s oxygen consumption doubles when
their body temperature. Scientists at
in ice-bath.
Harvard Medical School have shown that
Tibetan (Buddhist) monks that practice a form of meditation called Tum-mo, the same
meditation that Wim Hof practices, can raise the temperature in their extremities by 9.5°C
(15°F).
Oxgyen Consumption
ml/(kg*min)
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“Although the brainstem is an involuntary region of the brain, all areas of the brain are
connected. Therefore, it is likely through this meditation that Hof is able to reach a ‘state of
mind’ that influences the signals that are relayed from Hof’s brainstem to his body” suggests
neuroscientist Claire Scavuzzo from the University of Illinois. “This is only a prediction,
however.”
“Physiologically we call this a mystery and we need to do more research to really
understand how he can control processes in his body that we thought could not be
controlled voluntarily,” states Dr. Maria Hopman.
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What fuels us?
Lesson 1: Why is glucose important for the body and brain?
References:
Angier, J. (2008, March 7) Iceman on Everest: ‘It Was Easy’. ABC News. Retrieved from:
http://abcnews.go.com/Health/story?id=4393377
Hof, W., Hopman, M. (2010, November 11). Wim Hof. Retrieved from:
http://tedxtalks.ted.com/video/TEDxAmsterdam-Wim-Hof-113010
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October 2014