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The results of this study are entirely predictable. I see no mystery here at all. Exercise, especially aerobic conditioning promotes angiogenesis. The increased demand for oxygen and metabolic fuel by the tissues induces the development of collateral criculation. Ultimately, gas is exchanged at the microcirculatory level when erythrocytes are forced through the capillary bed and contact the intima of the conduit vessel. The more surface area for gas exchange, the better able for the system to transport dissolved gas to the alveolar pulmonary circulation and hence the critical level of dissolved inert gas, where bubble nucleation occurs, can me minimized. A heavily vascularized individual, without a PFO, will move more gas in and out of his system per unit time than the sedentary poorly perfused one. The Vo2 max test is an indirect indicator of vascularity. Even so, Captain Zero can be decompressed successfully if he ascends in such a differential fashion as to always maintain sub critical levels of circulatory gas. Unfortunately, the time and trouble involved make this impractical for in water decompression for certain extreme exposure dives. This is why the level of injury due to dcs in commercial diving is so low. The divers are decompressed very slowly and carefully in habitats so that tissue levels of inert gas do not reach levels where bubble growth is highly probable. The answer here is a very simple one. If you want to engage in extreme exposure mixed gas diving - and keep the decompression element of risk minimal - then you have to pay the price of extreme cardiovascular fitness. There is no other way. The requirement here is 5 - 6 days per week at no less than one continuous hour per day of intense cardiovascular exercise. Forget about about lifting heavy weights. That is complete and utter nonsense unless you perform endless repetitions. I suggest that some light weight lifting is ok, but don't kid yourself into thinking that this is a substitute for real cardio. You must run, swim, bike or utilize some type of aerobic conditioning artifice. Extreme cardiovascular conditioning is the best peremptive measure you can take to prevent DCS. Then of course there are turtle bones... Bill Mee Art Ranz wrote: > > I think the following is what you are referring to. This is the summary of > the article. I OCR'd it so the spacing is off, but the text is accurate. > Please be careful in reading the last line. It does NOT say that DCS is > independent of being fat, it says that conditioning helps the fat pigs too. > (so to speak). > It also suggests that being immature, male, and castrated helps promote > DCS!!!! > > Art > > Undersea & Hyperbaric Medicine, Vol. 22, No. 1, 1995 > Exercise conditioning reduces the risk of neurologic > decompression illness in swine > > J. R. BROOME, A. J. DUTKA, and G. A. MCNAMEE > Naval Medical Research Institute, 8901 Wisconsin Avenue, Bethesda, > Maryland 20889-5607; and National > Naval Medical Center, 8901 Wisconsin Avenue, Bethesda, Maryland 20889-5088 > Broome JR, Dutka AJ, McNamee GA. Exercise conditioning reduces the risk > of neurologic > decompression illness in swine. Undersea Hyperbaric Med 1995; 22(1):73-85. > > During development of a pig model of neurologic decompression illness > (DCI) we noted that tread-mill-trained pigs seemed less likely to develop > DCI than sedentary pigs. The phenomenon was formally investigated. > Twenty-four immature, male, castrated, pure-bred Yorkshire swine > were conditioned by treadmill running, while 34 control pigs remained > sedentary. All pigs > (weight 18.75-21.90 kg) were dived on air to 200 feet of seawater (fsw) > in a dry chamber. > Bottom time was 24 min. Decompression rate was 60 fsw/min. Pigs that > developed neurologic > DCI were treated by recompression. Pigs without neurologic signs were > considered neurologi- > cally normal if they ran on the treadmill without gait disturbance at 1 > and 24 h postdive. Of the 24 exercise-conditioned pigs, only 10 (41.7%) > developed neurologic DCI, compared to > 25 of 34 (73.5%) sedentary pigs ~2 = 5 97; P = CO.015). Neither mean > carcass density > (adiposity) nor mean age were significantly different between groups. No > patent foremen ovali was detected at necropsy. An additional control > group of 24 pigs was dived to clarify the influence of weight. The > results suggest that the risk of neurologic DCI is reduced by > physical conditioning, and the effect is independent of differences in age, > adiposity, and weight. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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