Hi Steven,
Yes you may quote me and I thank you for your kind comments.
Yes I swam Lake Malawi with Lewis Pugh in 1992. I know Lewis well and have had a long swimming and training history with him and his various challenges.
I am a Heart surgeon and Transplant and live and have a medical practice in Cape Town. I was a keen pool swimmer in my earlier career and turned to Masters swimming and open water swimming later.
I swam the EC in 1994, Gibraltar Straits in 2004 and did a relay EC in 2002. In and around Cape Town there are a number of well known swims that I have participated in, the memorable ones all relate to Robben Island in Table Bay.
Presently I swim and train just to keep in shape and hope to continue as long as possible.
Kind regards
OTTO THANING
—– Original Message —–
From: Steven Munatones
To: ‘Otto Thaning’
Sent: Wednesday, January 20, 2010 10:34 PM
Subject: RE: questions about cold water acclimatization from America – thank you very much
Dr. Thaning,
Thank you very much! This is wonderful information.
May I quote you on this subject for an article that I will post to www.dailynewsofopenwaterswimm.wpengine.com, www.worldopenwater.com and www.thewaterisopen.com? I think this is invaluable information for the global open water swimming community which is not as knowledgeable of hypothermia as is the English Channel swimming community.
Also, did you swim 25K across lake Malawi in 1992 with Lewis Pugh? I have written several stories about Lewis and we communicate via email, but I have never had the opportunity to meet him. What other marathon swims have you done and where are you from (currently or previously)? The reason why I ask is because I would like to properly introduce you for the article.
Thank you very much in advance.
Steven Munatones
From: Otto Thaning [mailto:otto@iafrica.com]
Sent: Wednesday, January 20, 2010 11:50 AM
To: Steven Munatones
Subject: Re: questions about cold water acclimatization from America
Dear Steven,
I attach my answers to your questions in a word document.
Please accept that the comments are only my personal opinions based on a long interest in open water swimming and a career in medicine. I do not profess to be a world expert!
Kind regards
OTTO THANING
—– Original Message —–
From: Steven Munatones
To: otto@iafrica.com
Sent: Tuesday, January 19, 2010 1:08 AM
Subject: questions about cold water acclimatization from America
Otto,
Thank you very much for providing that information to Mike Oram. Your knowledge and experience are impressed and very interesting.
I have a few questions:
1. You say that heat loss in swimming in cold water is mainly by conduction. What are other forms of heat loss, if not by conduction?
2. You say that when there is a temperature difference between the exposed parts of the swimmer’s body and the water, heat is loss. Whether one is thin or one is fat, is the AMOUNT of heat loss any different? That is, if heat loss is due to exposing parts of the body to the cold water, how and why is there any difference between a thin and fat swimmer? I would think the amount of skin surface of a fat swimmer is greater, so a fat person would lose more body heat.
3. You say that heat loss is reduced by increased body fat. Is that because body heat does not escape the internal organs because the heat is retained by fat cells in the human body?
4. Have there been any experiments where the relative drop in core body temperature of a thin person and fat person are compared? That is, if two people – one thin and one fat – with the same core body temperature are placed in cold water, and their core body temperature is measured after 1 hour, then the core body temperature of the fat person would be higher than the core body temperature of the thin person. Is this correct?
5. Men tend to gain weight around their stomach, while women tend to gain weight around their legs and hips. I would think that a weight gain closer to one’s core is “better” (i.e., more effective) for you. Would you say that men gain a relatively greater advantage with weight gain by women?
6. I swam in 12°C water for nearly 5 hours before collapsing in the water in 1984. My crew pulled me from the water and I woke up a few hours later in a hospital. I do not remember anything from about the 2-3 hour mark until I woke up in the hospital incredibly sore. Why was I sore?
Steven Munatones
www.dailynewsofopenwaterswimm.wpengine.com
Huntington Beach, California, U.S.A.
—– Original Message —–
From: channel_swimmers@googlegroups.com [mailto:channel_swimmers@googlegroups.com] On Behalf Of MICHAEL ORAM
Sent: Monday, January 18, 2010 12:11 PM
To: Google chat site Channel_swimmers
Subject: Fw: [Channel Group] Re: Body fat percentage
Otto Thanning sent me the e-mail below off-site as a reply to my posting.
I do think it is a very interesting read and Otto has said he is happy for me to post it.
Might help explain things a bit further Jim.
Acclimatise, Acclimatise, Acclimatise
It seems to be a big part of the answer.
Mike O
—– Original Message —–
From: Otto Thaning
To: michael.oram@btinternet.com
Sent: Monday, January 18, 2010 10:47 AM
Subject: Re: [Channel Group] Re: Body fat percentage
The thread on body fat percentage and its influence on the stable maintenance of body temperature has been very interesting.
I would like to add some personal observations:
It is important to recognize that the normal temperature of the human body is 37C. That temperature is the central, or core temperature. It has also sometimes been referred to as the cor (heart) temperature. It is the temperature of the internal organs of the body. This temperature is stringently maintained by complex physiological mechanisms under the control of many systems of the human physiology. The objective is to keep the environment of the major metabolic and enzyme functions of the body at a temperature at which they are most efficient, and that temperature in the human is 37C. That applies also to muscle and brain function.
The skin temperature or the sublingual temperature is a poor reflection of the cor temperature. The cor temperature is best measured by a rectal probe or thermometer! Please read the attached file for a suitable comment on that!
In some other mammalian species normal body temperatures are different from the human level of 37C. In reptiles the cor temperature is minimally or not at all controlled by physiological mechanisms.
Deviations in cor temperatures above or below 37C in man are abnormal. Deviations are usually the result of disease processes or extreme exposure to hostile environmental conditions. Swimming the English Channel is such a hostile environment.
In man HYPOTHERMIA is defined as a drop in COR temperature to below 35C. It is dangerous and if maintained low and can be responsible for morbidity or death either as a result of CNS depression, falling blood pressure, cardiac rhythm disturbances etc.
Maintenance of the cor temperature in cold water swimming is a balance between HEAT LOSS and HEAT GAIN.
Heat Loss in swimming in cold water is mainly by conduction. Where there is a temperature difference between the exposed parts of the swimmers body and the water, heat is lost from the warmer skin to the colder water.
This heat loss can thus be reduced by increased body fat which acts as insulation. I believe that the percentage body fat is important and needs to be more rather than less. A better measure of adequate body make-up is the Body Mass Index: (Weight in kg divided by the height in meters). Ideally I believe the BMI needs to be above 15 and less than 25. Obesity is defined as a BMI in excess of 25!
However, heat loss can be further minimized by early adaptation mechanisms that selectively reduce the peripheral circulation to the skin. This allows less heat loss by conduction as the superficial skin temperature rapidly equates to the water temperature, and as the skin circulation is reduced conduction loss is less and the cor temperature is protected.
Heat gain is a function of energy generated by the activity of muscles. A long swim thus has to be balanced to utilizing enough energy to balance the heat equation, but not too much to use up the reserves for the time required for the swim.
Cold water adaptation is a learned and trained ability to minimize heat loss.
Cold Water Adaptation is achieved by training the Autonomic Nervous System (ANS). The ANS has two subdivisions:
SYMPATHETIC System – that prepares for ‘flight’ or ‘fight’.
PARASYMPATHETIC System – that prepares for digestion rest/sleep.
These divisions of the of the central nervous system control BP, Pulse Rate, Respiration, rate of sweating, temperature etc… and function in synergistic balance – the one against the other. Only rarely do they act synchronously or out of balance. Their proper function maintains internal homeostasis.
Their function is automatic, but it can be influenced.
If you expose an untrained person to cold water, the normal heat conservation strategy only starts after the central or COR temperature has started to drop. If the initial heat loss is significant and the rate of heat loss is great, is becomes difficult to reverse the trend and conserve a cor temperature above required levels. In other words, once the central temperature falls substantially, you can never make it up, and hypothermia sets in and the swimmer will have to be taken out of the water.
Training the ANS for Cold Adaptation is by repeated exposure to progressively colder conditions by increasing periods of time (of exposure), and decreasing temperatures on each exposure. The process is gradual and should be over months, with avoidance of temperatures that are much lower than that expected for the swim anticipated.
As conditioning improves, the ANS reacts earlier and quicker to the ambient cold water temperature, and thus minimizes heat loss at an earlier stage. This training prevents or minimizes the initial drop in COR temperature, and thus it becomes possible to stabilize the cor temperature in a long cold swim.
Remarkably, it is possible for the ANS to anticipate a cold exposure, and for the cor temperature to actually rise in anticipation of the swim. This was accurately and scientifically documented during the training and preparation undertaken by Lewis Pugh in Cape Town by Professor Tim Noakes. Lewis was consistently able to get his cor temperature to 38.4C prior to cold exposure. Lewis was, as I am sure you all know, was preparing for his swim at the North Pole in 2008.
See:
http://www.youtube.com/watch?v=6sS8OcEwXNs)
The condition of increasing cor temperature in preparation for a cole swim is now known as Anticipatory Thermogenesis, and I do not believe it is unique. I believe most of us are able to achieve it with adequate training although its real value becomes only relevant if the cold exposure is going to be the levels that Lewis Pugh attained in swimming a kilometer in zero degrees centigrade!
Because I remain a purist, and as the challenge of swimming the English Channel is significant, I believe any attempt to promote the use or acceptance of any aid to facilitate the swim other than a costume, a cap and a pair of goggles, diminishes the achievement.
I think that Michael Oram has admirably explained the issues that relate to the alternate categories that are now available in swimming as part of a relay, swimming with aids or wet suits etc… These all help to increase the awareness and appreciation of a noble sporting endeavor, that of swimming.
In the minds of the purist, swimming the Channel and being recognized as having succeeded remains a challenge of the time spent in the cold waters, armed only with the background of adequate training, a simple costume, a cap and a pair of goggles, and this alone is the gold standard of this endeavor.
OTTO THANING
Cape Town
Copyright © 2010 by Steven Munatones