Dehydration - is it really *that* bad?

[Wayne at DiveSeekers]

Mr. Carcharodon,

Clearly, this study was not done on humans and no I have never gone 1300 mins past NDL and blown off Deco. The long and short of it for me is that I always want to be at Optimum Health when diving especially when I am on Deco Dives and being Dehydrated is Not being at Optimum Health. Looking back on dives that I use to do before I had a change in philosophies (in regards to Health & Fitness) I feel much better now both during and after my dives (especially deco ones) then I did back then.

[RJP]

Properly hydrated vs not? I'll choose properly hydrated, thanks.

[dumpsterDiver]

I'm surprised by the opinions expressed. Also missing (I think) was a mention of immersion diuresis which, as i understand it, is a significant factor in causing divers to lose water.

I generally try to drink a little more water then i think I need when diving. In the morning it is breakfast and a cup of coffee (yah i know) and then a 20-30 oz big gulp cup of water on the drive to the boat. I bend enough diving rules, pissing a little more often on the boat is the least of my worries.

[Thalassamania]

DAN finds the evidence inconclusive that dehydration increases DCS risk. Nevertheless, there is anecdotal evidence to support the hypothesis and there is no downside to being adequately hydrated, so why would you not?

While I wouldn't recommend (or drink) Coke or Pepsi or Gatorade, any of them will do an adequate job of hydrating you—not optimal, but adequate. You don't need a sports drink—scuba's barely (if at all) a sport. Water is great, diluted Gatorade is not that bad, and Coke is better than nothing, from a hydration standpoint. Yes, caffeine is a diuretic, but its effect does not offset the liquid you consumed with it.

The actual DAN quote is: "Rapid ascents are closely linked to the risk of AGE. Other factors thought to increase the risk of DCI but for which evidence is not conclusive are obesity, dehydration, hard exercise immediately after surfacing, and pulmonary disease. In addition, there seem to be individual risk factors that have not yet been identified. This is why some divers seem to get DCI more frequently than others although they are following the same dive profile."

Be that as it may, dehydration is linked to electrolyte imbalance and muscle cramps. Muscle cramps are bad when diving.

[vladimir]

The actual DAN quote is: "Rapid ascents are closely linked to the risk of AGE. Other factors thought to increase the risk of DCI but for which evidence is not conclusive are obesity, dehydration, hard exercise immediately after surfacing, and pulmonary disease. In addition, there seem to be individual risk factors that have not yet been identified. This is why some divers seem to get DCI more frequently than others although they are following the same dive profile."

Yes, thanks Thal. That is from the article I linked to and that is the quote I was relying upon.

[tajkd]

Define properly hydrated. No one has been able to do so relative to diving safety. How much is enough? How do.you measure it?

[danvolker]

Define properly hydrated. No one has been able to do so relative to diving safety. How much is enough? How do.you measure it?

I don't think you are going to get this measured out for you. The most important step for most divers, is going to be proper hydration during the days preceding the dive trip, so that they don't begin their dives as dehydrated.
For many people that work out at least a little, a gallon or more of pure water every day is a minimum. Of course, quantity needed will be different between a 110 pound woman and a 200 pound man....then factor in activity levels and metabolic differences. Personally, the only way I have ever been able to optimize my own hydration when I am training hard on the bike ( and need 2 gallons of water per day), is to carry around a one gallon bottle of water, and sip it every few minutes. Ultimately, I will get through 2 gallons per day like this. It causes massively better recovery from workouts, your digestive system seems to pass food through itself faster, and energy levels go up. Giles has put thousands of athletes through special diets and they always include 2 gallons per day of water or more. These athletes would have been paying him $10,000 to $25,000 for a one week diet and training. They would also have daily feedback from him on the diet and water balance, along with the daily training. His successes with Olympic and pro level athletes is legendary, and to me trumps the arguments of those claiming that you only need a few cups of water per day--these people/scientists will have NO track record for elite performance athletes. Divers may not necessarily be elite performance athletes, but the mechanism gets proven to me by the effects on the athletes--so I am going to assume this mechanism will be effective for divers.

[mike_dippert]

Define properly hydrated. No one has been able to do so relative to diving safety. How much is enough? How do.you measure it?

In Boy Scouts, they told us if your pee is yellow, your aren't drinking enough water. while not entirely accurate, its not a bad rule of thumb.

[TSandM]

tajkd, nobody CAN define properly hydrated for diving, because it isn't even really known how much of a risk factor dehydration IS, let alone what the threshold is for increased risk. But I can define WELL hydrated -- if you are urinating every couple of hours, and your urine is very light yellow in color, you are well hydrated.

[DocVikingo]

Wayne, When was the last time you went 1300 minutes past your NDL and did not do any deco? How relevant is that study for recreational or tech divers?

Thank you, Mr Carcharodon.

And that is not to mention:

1. The study swine (who obviously were not human) underwent compression in a dry chamber environment v the wet environment compression experienced by divers. I have a passing interest in this distinction and many of the works I have read that have addressed dry v wet compression have demonstrated differences in the dependent variable(s) under study.

2. This study focused on outcomes of death and non-fatal central nervous system (CNS) or “cardiopulmonary DCS”. Although still quite rare, far, far more common in divers than these is the range of Type I DCS manifestations. For understandable reasons, this form of DCI could not be assessed.

3. The study pigs were dehydrated using a potent IV diuretic v the natural mechanisms of dehydration in divers such as immersion diuresis, elevated levels of C02, and breathing hyper-dry gas. We have no idea what the implications of this difference is for the question under discussion.

Based on the totality of the research available thus far, I do not find the cited swine study compelling.

Regards,

DocVikingo