On what scientific basis do you draw your conclusions that drinking too much before a dive can make you dehydrated after? I'm a scientist and that sounds pretty illogical to me.....unless of course you are doing a lot of peeing in your wetsuit!TeddyDiver:
(6/28/2005) Like your exercise? Ever been bent? Read this
- Thread starter Nobby
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I think you hit the nail on the head. Alcohol works to some degree as a diuretic, but it's not an instant effect. Not only that, it also strips out a lot of the minerals and other "minor essentials" in your system at the same time, which is why I feel hung over right now despite only having drunk a small amount and I should by now be completely rehydrated (time to get some gator aid).Nobby:
Charlie99:
The improved method is paying attention to all of the factors. In all likelihood this guy took a minor hit due to dehydration. Assuming you do everything else perfectly, hydration, ascent rate, general profile, etc., NDLs are extremely conservative for most people. The problem is that you pretty much never do everything perfectly and your dive profiles need to account for this. Messing up just one factor usually won't do it. For instance having a few drinks, probably still okay within the NDLs. (Remember, they are very conservative.) Having a few drinks + not getting enough water = more likely to get whacked even in the conservative NDL limits. Or maybe still okay but add a third screw up of too fast of an ascent or a saw tooth profile, etc., etc. and then you get hit.
Thinking that you are fine as long as you follow your dive computer and don't pay attention to all of these other variables which tend to add up and be more important than whether or not your bottom time was 5 minutes closer to or over the theoretical limit is how computers rot your brain. UPs methods are pretty cool, but the important aspect of them (in my view) is that they make it more likely you will take into account all of these other variables too since you actually think about your profile rather than blindly following what the blinking lights tell you.
Nobby:
Having a lot of water in your body during the dive rises the amount of soluted nitrogen. It's simply a question about partial pressures (PN2) equalizing. Sweating and urinating during and after the dive enriches the PN2 unless one doesn't "exhale" it throw the skin or pii champagne (don't know about this). He also drinked coffee which is much better diuretic than alcohol (which he also had).
I don't believe that any of these factors could alone made bends, but having many little things gone a bit wrong could make the difference when added together (also the possible influence of workout and profiles of the dives).
Perhaps sweat and urin contain same amount of nitrogen as ones body tissues, but I believe it's more important to be well hydrated after the dive. Thats anyway the time when PN2 reaches the max...
Canadian_Diver
Contributor
Sorry if this has already been covered, I was too lazy to read everything between the first and last page.
Assuming that he was doing a normal recreational dive using a single 80cuft aluminum tank filled to maximum capacity, 70+ minutes seems a bit far fetched.
I can burn an 80cuft aluminum down to 500psi just over an hour if I stay above 30 feet and focus on air management. I don't consider myself a light breather, but I'm no air hog either. With a maximum depth of 105ft, and an average depth of 60ft, that seems a little impossible to do a dive for 70+ minutes with that type of profile.
My personal best is 1hr and 2mins on an 80cuft aluminum. Maximum depth was 50ft, and I averaged about 40ft throughout the dive.
What type of tanks was this guy diving on? Was he tech diving or rec diving? :06:
..... on the dehydration issue ..... I find Powerade or Gatorade does wonders for me during my surface intervals. The drinking issue, I limit myself to 2 drinks maximum well before I go to sleep the night before a dive, and drink double that in water. In the morning, I stay away from coffee, softdrinks, or anything else of the likes. I'll drink applejuice, which helps replenish some of the nutrients in the body, and eat a decent meal, usually one egg, rye toast, and sausage. I'm ready to go with no hangovers or dehydration.
Assuming that he was doing a normal recreational dive using a single 80cuft aluminum tank filled to maximum capacity, 70+ minutes seems a bit far fetched.
I can burn an 80cuft aluminum down to 500psi just over an hour if I stay above 30 feet and focus on air management. I don't consider myself a light breather, but I'm no air hog either. With a maximum depth of 105ft, and an average depth of 60ft, that seems a little impossible to do a dive for 70+ minutes with that type of profile.
My personal best is 1hr and 2mins on an 80cuft aluminum. Maximum depth was 50ft, and I averaged about 40ft throughout the dive.
What type of tanks was this guy diving on? Was he tech diving or rec diving? :06:
..... on the dehydration issue ..... I find Powerade or Gatorade does wonders for me during my surface intervals. The drinking issue, I limit myself to 2 drinks maximum well before I go to sleep the night before a dive, and drink double that in water. In the morning, I stay away from coffee, softdrinks, or anything else of the likes. I'll drink applejuice, which helps replenish some of the nutrients in the body, and eat a decent meal, usually one egg, rye toast, and sausage. I'm ready to go with no hangovers or dehydration.
Canadian_Diver:
Well, I think that is just the way he described it. I did some dives in Bonaire where I hit 100 feet and the entire dive lasted 90 minutes. Of course there was lots of interesting stuff in the shallows around 30 feet and in Bonaire I had an SAC of 0.25cu ft/atm/min. If it had been a VA wreck dive on the other hand where you cannot stage your ascent and it's wreck or above the wreck and end of dive there's no way I could have managed 70+ minutes, but 20-25 is no problem.
For anyone interested in what this thread touched on numerous times...
I just love this webiste: www.divefitness.com
------------------------------------------------
Exercise Before Scuba Helps Prevent the Bends
Intensive Exercise 24 Hours Before Scuba Diving Prevents Decompression Sickness
By Jeanie Lerche Davis
WebMD Medical News Reviewed By Michael Smith, MD
on Friday, March 12, 2004
March 12, 2004 -- A single session of high-intensity exercise may greatly cut the risk of decompression sickness. However, timing is critical -- exercise must be done 24 hours before scuba diving, a new study shows.
This is the first time that researchers have pinpointed pre-diving exercise as a way of preventing decompression sickness. However, further study is needed before this can be widely adopted as a predictable safeguard, writes John R. Claybaugh, PhD, an investigator with the Tripler Army Medical Center in Hawaii.
Decompression Sickness: Serious Threat
Decompression sickness following diving is a constant threat brought about by the formation of gas bubbles in blood vessels, writes lead researcher Zeljko Dujic, PhD, a professor of physiology and biophysics at the University of Split School of Medicine in Croatia. His paper appears in this month's issue of the Journal of Physiology.
"There is a growing concern that diving can lead to permanent damage to the central nervous system, even in the absence of clear signs of decompression sickness, and one of the suspected mechanisms is silent bubble formation," he writes.
The researchers had previously shown that a single bout of high-intensity exercise 20 hours before a simulated dive in rats reduced bubble formation and after the dive protected from lethal decompression sickness. Studies of human divers show bubble formation is less if they are in good physical shape.
Timing Is Everything
In this study, Dujic recruited 13 men -- all under age 40, all very experienced divers. None had ever had decompression sickness. Each was asked to do a treadmill running workout within 24 hours of their dive.
The first three minutes was at 90% maximum heart rate, then reduced to 50% maximum heart rate for two minutes. They repeated this pattern eight times for a total exercise session of 40 minutes. Maximum heart rate is calculated as 220 minus your age.
During a simulated scuba diving exercise, gas bubbles were monitored with an ultrasonic scanner every 20 minutes for 80 minutes after reaching surface pressure. Each diver performed two dives seven days apart -- one with and one without physical exercise 24 hours before.
When the men exercised 24 hours before their dive:
None of the divers had any symptoms after diving.
Both the number of bubbles and the size of the bubbles decreased significantly, compared with diving without exercise beforehand.
Timing and intensity of the exercise is important, he adds. Research in rats from his laboratory and others shows:
Low-intensity exercise does not help.
Exercising strenuously within 10 hours before scuba diving does not help.
Exercising strenuously 48 hours before diving does not help.
Although Dujic is not sure how exercise helps protect against decompression sickenss, he speculates that nitrous oxide production during exercise is somehow involved.
The finding warrants more study before it can be recommended as a preventive before scuba diving, he adds.
SOURCE: Dujic, Z. The Journal of Physiology, March 2004: pp 637-642.
© 2004 WebMD Inc. All rights reserved.
I just love this webiste: www.divefitness.com
------------------------------------------------
Exercise Before Scuba Helps Prevent the Bends
Intensive Exercise 24 Hours Before Scuba Diving Prevents Decompression Sickness
By Jeanie Lerche Davis
WebMD Medical News Reviewed By Michael Smith, MD
on Friday, March 12, 2004
March 12, 2004 -- A single session of high-intensity exercise may greatly cut the risk of decompression sickness. However, timing is critical -- exercise must be done 24 hours before scuba diving, a new study shows.
This is the first time that researchers have pinpointed pre-diving exercise as a way of preventing decompression sickness. However, further study is needed before this can be widely adopted as a predictable safeguard, writes John R. Claybaugh, PhD, an investigator with the Tripler Army Medical Center in Hawaii.
Decompression Sickness: Serious Threat
Decompression sickness following diving is a constant threat brought about by the formation of gas bubbles in blood vessels, writes lead researcher Zeljko Dujic, PhD, a professor of physiology and biophysics at the University of Split School of Medicine in Croatia. His paper appears in this month's issue of the Journal of Physiology.
"There is a growing concern that diving can lead to permanent damage to the central nervous system, even in the absence of clear signs of decompression sickness, and one of the suspected mechanisms is silent bubble formation," he writes.
The researchers had previously shown that a single bout of high-intensity exercise 20 hours before a simulated dive in rats reduced bubble formation and after the dive protected from lethal decompression sickness. Studies of human divers show bubble formation is less if they are in good physical shape.
Timing Is Everything
In this study, Dujic recruited 13 men -- all under age 40, all very experienced divers. None had ever had decompression sickness. Each was asked to do a treadmill running workout within 24 hours of their dive.
The first three minutes was at 90% maximum heart rate, then reduced to 50% maximum heart rate for two minutes. They repeated this pattern eight times for a total exercise session of 40 minutes. Maximum heart rate is calculated as 220 minus your age.
During a simulated scuba diving exercise, gas bubbles were monitored with an ultrasonic scanner every 20 minutes for 80 minutes after reaching surface pressure. Each diver performed two dives seven days apart -- one with and one without physical exercise 24 hours before.
When the men exercised 24 hours before their dive:
None of the divers had any symptoms after diving.
Both the number of bubbles and the size of the bubbles decreased significantly, compared with diving without exercise beforehand.
Timing and intensity of the exercise is important, he adds. Research in rats from his laboratory and others shows:
Low-intensity exercise does not help.
Exercising strenuously within 10 hours before scuba diving does not help.
Exercising strenuously 48 hours before diving does not help.
Although Dujic is not sure how exercise helps protect against decompression sickenss, he speculates that nitrous oxide production during exercise is somehow involved.
The finding warrants more study before it can be recommended as a preventive before scuba diving, he adds.
SOURCE: Dujic, Z. The Journal of Physiology, March 2004: pp 637-642.
© 2004 WebMD Inc. All rights reserved.
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