Dr. Deco has done some rather elegant studies that have shown an increase in bubbling associated with exercise immediately post decrease in pressure.(Ascending from a dive or ascending to altitude).
http://www.scubaboard.com/showthread.php?s=&threadid=1554&highlight=exercise+and+DCS
Imbibing alcohol (beer) in the peri-dive time frame is also dangerous from the standpoint of altering reaction times and clouding the sensorium. The effects of a few beers have been shown to cloud the sensorium long after one would ordinarily think that the alcohol has been metabolized, the obtunding effects of alcohol have been shown to be detrimental to the diver if imbibed as much as twelve hours prior to the dives. It has also been shown that it increases the risks of DCS by causing diuresis and dehydration.
A study by Perrine, Mundt and Weiner found (scuba) diving performances significantly degraded at blood alcohol levels of 40 mg/dl (04%BAC). They also cite a clear increase in the risk of injury at this level which can be reached by a 180 lb. man who ingests two 12 oz. beers in 1 hour on an empty stomach. This very pertinent study once again points out that there is a diminished awareness of cues and reduced inhibitions at relatively low levels of blood alcohol. Their study used well trained divers who were being paid to do their best as their diving performances were being videotaped.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7990461&dopt=Abstract
Dr. Glen Egstrom, PhD has stated the problem succinctly: He made personal review of over 150 studies on the effects of alcohol on performance has resulted in the following observations:
1. Ingestion of even small amounts of alcohol does not improve performance: to the contrary it degrades performance
2. While there are variables that can speed up or delay the onset of the effects of alcohol, they are minor issues which do not overcome the decrements to the central and peripheral nervous system.
3. Alcohol can be cleared from the blood at a predictable rate. Generally on the order of .015% BAC per hour. This does not necessarily mean that the decrements in performance have been completely eliminated in that time.
4. Alcohol is a depressant drug that slows certain body functions by depressing the entire central nervous system. Effects are noticeable after one drink.
5. The effects are mood elevation, mild euphoria, a sense of well being, slight dizziness and some impairment of judgment, self control, inhibitions and memory.
6. Increases in reaction time and decreases in coordination follow the dose/response curve quite well.
7. Alcohol is involved in 50% +/- of all accidents involving persons of drinking age.
8. The deleterious effects of alcohol on performance are consistently underestimated by persons who have been drinking alcohol.
9. Divided attention tasks are found to be affected by alcohol to a greater degree than those tasks with single focus of concentration, i.e. a task such as a head-first dive into shallow water, with many interrelated decisions necessary to a successful dive, will be impacted to a greater degree than lifting a heavy weight.
http://www.jellis.com/news/96news/may96/alcohol.htm
For more information see our article at
http://www.scuba-doc.com/alch.htm
Best regards for safe diving!
scubadoc
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