Medical Update
Medical Update
Posted by Martin Rhodes

Friday, 01 May 2009 00:00

Whilst Pen, Ann and Martin enjoy the luxuries of today’s resupply, let’s not forget that this is their 65th day of their expedition.

 “Our spirits are restored.  Now we just need our bodies to catch up,” said Ann.

The statistics of their trip beggar the imagination of those who have not had the privilege of travelling in the Arctic wilderness, but they do give some indication of the huge stresses the environment is putting on their bodies.

If they were trekking with 20kg rucksacks in 65 days they could have travelled 2500km, the distance from Paris to Moscow.

 In 65 days the Team have travelled 397km, and averaged 6.12km/day.

Polar travel is an exercise in controlled starvation. Earlier this week Ann was dishing out 1000kcal daily rations. Even absolutely still in a sleeping-bag waiting for a resupply, they each require perhaps 2500kcal to supply their resting metabolic needs, the energy to cook and melt water, and to shiver and to move in order to keep warm. On the move their average energy expenditure will be in the region of 5000-6000kcal a day

The awful truth is that their bodies will not catch up until they are off the ice. It is likely that they will lose between 30-40% of their body-weight, and their fat levels will drop to practically nil. During Mike Stroud and Ran Fiennes’s crossing of Antarctica in 95 days they lost 25 and 22kg respectively.

We have just received a further set of measurements from the Equivital equipment the Team are wearing and swallowing. These give 15,596 readings of Heart Rate, Core and Skin Temperature and Respiratory Rate over a 24 hour period

Two facts are apparent on an initial analysis. The first is the body’s amazing ability to maintain its internal environment whatever external extremes it is subject too. The second is that there are significant individual differences in the actual readings. Core temperature in particular remains within a very small range. All the Team maintain a core temperature within the expected 36.5ºC – 37.5ºC, with skin temperatures in the low 30’s. There does seem to be a difference in skin temperatures amongst the Team members, with Ann’s average temperature being perhaps 2ºC higher than either Pen or Martin. The skin temperature is relatively constant in spite of variations in the external temperature, but this is to be expected as the temperature gradient between the body’s core and the Arctic environment is in the region of 80ºC.

A further example of the individual differences can be seen in Pen’s pulse rate. Pen tends to work at a heart rate between 60-80, rarely exceeds 110 and has a sleeping pulse in the low 40’s. Ann and Martin tend to work at 80-100, have peaks of 140-150 and sleeping rates of 60-70. These figures are relatively consistent. However, they do not reflect fitness levels, rather a  genetic set-point at which their bodies are working as efficiently as possible and all the Team members are putting in the same amount of work, day in, day out.

Further analysis of the Equivital data should give us further insights into the body’s response to these extreme stresses



Category: Biotelemetry
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