apitkin

The big confounder in relating body fat to decompression risk is exercise. There is quite a lot of evidence now pointing to a protective effect of exercise. Jon Broome showed this effect elegantly in a porcine model of severe spinal DCS where he found that sedentary animals had nearly twice the risk of suffering severe DCS than those that exercised (IIRC) to 60% of max predicted heart rate once a day for about 30 minutes. The neat thing was that he showed that there was no difference in body fat between the two groups.

Alf Brubak has shown similar results in rats, although it's not a new observation in rodents:

Cross-adaptive effects of cold, hypoxia, or physical training on decompression sickness in mice

How long, how much and what kind of exercise you need to get the protective effect (which can be significant) is not exactly clear. Doing regular exercise and including a session within the 48 hours before the dive is probably the best currently available advice.

I think it's safe to say that there is not a simple relationship between body fat percentage and DCS risk.


Andy

jkaterenchuk

Andrew

Nothing scientific. There was another diver on the trip that had been in the study earlier in Grand Cayman and had exactly the same result as I did on deep dives. He was also using 20/85. He decided to change to 30/85 and the post dive results improved in a similar fashion to mine. So I decided to do that also. There was not enough time to try different combinations. If I get to participate in the study again I would try some others.

I think I know why your asking and I quess all this flys in the face of deep stops since the change from 20 to 30 eliminates a deep stop or two depending upon depth so it gets you shallower quicker and then the 85-75 keeps you there a little longer. All I can say is the screen showed the results and anyone looking at it would be as surprized at the magnitude of the impact as I was.

John

wedivebc

wouldn't that follow the same logic as your fast ascent on deep dives.Reduce ongassing slow compts at depth.

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danijeladir

John you are right of course. changing the dive plan will have greater (and imidiate) impact on your deco. Also going from 16 to 10% of BF is hard. You can reach that goal in many, more or less healty ways. Training, diet, "chemicaly assisted" etc. But this should not be the main goal. A good training and food plan can bring you a long way, and at the end if you reach that 10 or whatever BF% I am positive you will be more efficient during deco. Not only because of your BF but because you have a more efficient and healty body. It is just a peace of a puzzle and it should not be overrated.

Mirko

gsk3

Hard to see how you can come to this conclusion from your anecdote.... Everyone else on the boat was presumably diving similar profiles. So individual variability clearly matters. But does obesity matter above and beyond individual variability?

Here's a chunk of evidence on that question:
Search

Fun Under Pressure

My buddy and me we where in south france for wreck diving, JP Imbert come with a second dr to do some examination of the divers, after every dive we had a bubble detection via a thoracic ultrasonic examantion, my buddy is 195 cm high und he weight arround 140 kg, i am 175cm high and i weight 86 kg, after the second dive ( 100m ; 20 min bt, 3 hours dt) i have had a few small bubbles and my buddy have nothing,.... since then i am not sure if fat means you are more in the risk of getting dcs,....after the third dive, same profil, we both have nothing...

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