Research
on Breath-Hold
Freiburg im Breisgau | August 20, 2009
Undergoing scientific testing is a great way for breath-hold
divers to better understand their body and to see if
their (usually rigorous) training is adapted to their
particular physiological disposition.
William was recently fortunate to meet
with Dr.
Stephan Walterspacher, MD, and his medical research
team at the department of respiratory medicine of the
university hospital of Freiburg im Breisgau, Germany.
Dr. Walterspacher and his team are
very interested in safety aspects of breath-hold diving.
One of their focus is on a technique frequently used
by freedivers: buccal pumping (commonly known as packing
in freediving lingo) as it relates to the lungs and
central nervous interactions during breath-hold diving.
Together with his team, Dr. Walterspacher is currently
conducting two research projects:
Research project #1
Setting: Neurology laboratory
With a highly experimental setup, oxygen saturation
is examined within the central nervous system during
maximal dry breath-holds, using near infrared spectroscopy
(a non-invasive technique (just like measuring oxygen
saturation using a finger clip) using near-infrared
light).
Why: Tests are carried out to see if the deoxygenation
(occuring during long-term breath-holds) might lead
to cerebral damage. In fact, a very recent publication
in the Journal of Applied Physiology identified
specific protein markers which would indicate brain
damage taking place during long breath-holds. This
might be due to insufficient blood-flow regulation
during breath-holds.
William states: "The infrared
experiment was cool: if you look at the photos, you
see them outfitting me with the system of sensors. There
were about 35 light-emitting diodes on my head along
with a set of headphones as I sat in front of a monitor,
holding my breath and waiting for the loud music and
obnoxious visuals to appear. It was not easy doing in
excess of 4-minute breath-holds sitting bolt upright
with my chin resting in position on a tripod but, I
managed it."
Results for this particular experiment will be produced
in several months.
Research project #2
Setting: Respiratory laboratory
Routine measurements of lung volume and respiratory
muscle strength are taken. Furthermore, the respiratory
drive is studied using several concentrations of carbon
dioxyde and lung compliance.
Why: The research team is, on one hand, looking
for long-term damage signs in the lungs in divers
whom they have studied for the last three years; on
the other hand, they are looking at short-term damage
signs of the lung by measuring lung compliance in
their current subjects on a breath-hold after buccal
pumping. They have found a promising marker in blood
and urine that might show them how much damage to
the lungs occur. Finally, they take a close look at
how "sensitive" divers are reacting to increasing
levels of carbon dioxide.
How: Urine and blood samples are taken to look
for specific markers indicating lung damage (if any)
when breath-hold divers pack extra air in their lungs
using buccal pumping. Compliance of the lung is also
measured using a pressure sensor placed in the oesophagus.
Finally, the response to increased levels of carbon
dioxyde is measured while looking at the increment
of respiratory drive measured using spirometry.
William recalls: "Imagine swallowing
a catheter containing two evenly-spaced small balloons,
all the way down to your stomach... Well, this one starts
by passing through your nose out the back and then down
the throat. Once in place, I had to take a few deep
breaths hooked up to a computer so Dr Walterspacher
could make sure the balloons were at the right level
of the esophagus and then the experiment could begin.
As I inhaled fully the balloons registered the elasticity
of my lung tissue and then I packed as much air in as
I could and once again the balloon system measured the
elasticity during the overpacked breath-hold. I had
to do several repeats of all of this and then the machine
got a reading as to whether or not my lung elasticity
was changing throughout this process. If swallowing
the tube was not enough, I can tell you that doing breath-holds
with little balloons in my oesophagus felt quite strange."
"The final test was to see how
I would respond to increasing levels of carbon dioxyde.
For this experiment, I was hooked up to a closed circuit,
within which the levels of carbon dioxide were gradually
increased under the command of Dr Walterspacher. My
responses to the varying levels of the gas were recorded.
Contrary to the general population who increase their
rate and frequency of breathing when exposed to higher
levels of CO2, trained apneists like myself, tend to
increase the volume of air exchanged in the lungs but
not the frequency of the breath. This was interesting
because earlier in the day, during the infrared spectroscopy,
my carbon dioxide level was also being monitored and
it was observed that without hyperventilating I was
able to lower my carbon dioxyde level by 14%, just through
deep, relaxed breathing like when I practice Tai Chi
or Chi Gong."
So far, Dr Walterspacher has drawn
some conclusions from parts of the experiment. He explains:
"William exceeded the average population by far.
We can tell by the body plethysmosgraphy that he has
a very trained lung, that means a large lung. He is
able to breathe hard and fast and he can use a lot of
his lung volume in a very short time. This is quite
outstanding as can only be seen in very trained subjects.
Interestingly, his response to CO2 does not seem to
be as "delayed" as in other breath-hold divers;
presumably he did not try to control it as much as the
others. But, in contrast to the general population,
breath-hold divers, including William, respond to CO2
mainly by increasing their tidal volume and not by increasing
their breathing frequency. There is, and that's a good
thing, no change in lung elasticity, as measured by
lung compliance, compared to normal subjects; indicating
that there might not be overwhelming harm done to the
lung by performing the packing manoeuver."
For those of you reading and who are
trained breath-hold divers, if you are interested in
what is without a doubt very interesting research and
would like to help out, please contact Dr.
Stephan Walterspacher as he is looking for more
volunteers. While the experiments described above are
now actually almost finished, Dr Walterspacher already
has plans for future studies in the beginning of 2010.
He will be happy to meet with new elite divers (criteria:
breath-hold duration of at least 5 minutes, diving for
at least 2 years).
William Winram would like to thank
Dr. Stephan Walterspacher and Sebastian Vogel of the
University Hospital Freiburg, Department of Pneumology,
Germany for carrying out this experiment despite the
overwhelming summer heat.
Photos by Elizabeth Golay
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Dr. Walterspacher
M.D. and his assistant fitting William's head with about
35 diodes
Infrared spectroscopy
experiment in progress
Dr Stephan Walterspacher
measuring William's lung volume during a whole body
plethysmography experiment
Swallowing water
and catheter together prior to the lung compliance test
Testing lung tissue compliance
through packing (buccal pumping)
Dr Walterspacher goes over the preliminary results with William
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