On
Rehydration
(published
in Tournaments Illuminated #152, Fall 2004)
There has been a long-standing argument about how to properly hydrate during SCA activities. There are proponents of everything from pure water up through full-strength sports drinks with various additives. While the Ether sings with the debate and sports drink companies rake in the guineas,recent studies have thrown some light on this arcane topic.
In order for the body to operate at peak efficiency, it needs to do four things: 1) maintain body temperature 2) maintain hydration 3) maintain energy levels, and 4) maintain electrolytes (salts, especially sodium).
Peak
exercise efficiency
occurs at a body temperature slightly above normal (thus the
recommendation to
“warm up” prior to exercise). To keep from
overheating, the body
produces sweat
which cools by evaporation. The sweat contains water and salt, however
the
concentration of salt in sweat is less than in the blood. Therefore,
when you
sweat, you lose water faster than you lose salt. As you become more
used to the
heat, the sweat becomes even more dilute and you lose even more water
in
proportion to the salt loss. This means it is much more important to
replace
water than salt, at least in the short run. Most SCA combat activities
don’t
last long enough to require additional energy supplements (such as
carbohydrates) during that activity. Energy can be replenished by
having a
small snack between bouts in a list. During extended melees or wars
there may
be benefit to rehydrating with a carbohydrate-containing drink.
What
is the
best way to
replenish what the body needs? At a minimum, you should be drinking
water. The
best method is taking small amounts frequently, such as 8 oz (240 mL)
every 15
minutes. Long distance runners that drink 500 mL (one pint) an hour
during a
race lose 5 – 6% of their body weight – all from
water loss. Daily
water
requirements range from 2 L (2 quarts) in normal climates with low
exercise to
15 L (4 gallons) with heavy exercise in the desert. If you want to know
how
much water you’re loosing, weigh yourself before and after
exercise
(naked –
you don’t want to weigh the sweat soaked into clothing). The
difference
is the
amount of water you’ve lost. The best way to tell if
you’re adequately
hydrated
is by paying attention to your urine. If it’s been more than
a couple
of hours
since you’ve visited the Port-a-Castle, you’re
probably not adequately
hydrated. Your urine should be no darker than weak lemonade. Also, if
you’re
thirsty, you’re already 1 – 3% dehydrated.
The
salt
losses are
more than adequately replaced by eating a normal diet. The goal is to
replace
water loss minute-by-minute and salt losses day-by-day. While there
have been
reports in the news and sports magazines about people having problems
from
drinking excessive water (hyponatremia or water intoxication), this is
actually
very rare and usually only seen in endurance races such as
ultramarathons where
the participant drinks excessive amounts of water over several hours of
participation. Dehydration is much more common in SCA activities.
Don’t
hold
off drinking water for fear of this rare condition.
The
down-side to water
is not everybody finds it tasty, especially when you have to choke down
the
amounts it takes to remain well-hydrated. This is probably the biggest
reason
to use a flavoring in the water. Also, water will sometimes satisfy
your thirst
before you’ve drunk enough to replenish your body’s
stores. Some salt
in the
water will also help encourage drinking more.
The
ideas
about
effects of the carbohydrate (sugar) content of sports drinks has
changed over
the years. Some studies from the 1960s showed that carbohydrates in
drinks
slowed the rate that they are absorbed from the stomach. This is the
reasoning
behind the recommendation to dilute sports drinks in half. More recent
studies
have shown this not to be true. However, drinks with more than about
10%
carbohydrate content can cause cramps, nausea, and diarrhea. Not
something you
want to have in the finals of Crown Tourney, or, as one author put it,
“You'll
be running, but not necessarily on the field!" Products
that are under 8% carbohydrate do not need to be
diluted. Gatorade®
at its recommended strength is 6% carbohydrate, and therefore does not
need to
be diluted. Diluting
the drinks can make the mixes go
farther and can make limited money and/or supplies last longer. The
composition of
several sports drinks can be found at:
http://www.powerbar.com/Products/Beverage/BevSystem/ProductComparsonChart10-16.pdf (sorry, link has been removed)
A
misconception commonly encountered is that drinking cold drinks causes
stomach
cramps and delays stomach emptying. This has not been borne out in
experimental
trials. In fact, cold liquids stimulate the emptying of the stomach.
Cool
drinks are probably still better tolerated than ice cold (ever get a
‘brain
freeze’?)
If you use carbohydrate-containing drinks, be careful that the containers are protected from insects. Bees and other stinging insects especially like sweet drinks. Rapidly swigging down a drink that contains a bee quenching his thirst can be very surprising for both the bee and the drinker, with disastrous results for both. Sports-top bottles are great for keeping the insects out and are easy to squirt through most helms. Soda cans are terrible as you can’t see what you’re drinking – be it hornet or cigarette butt! Make sure sweet liquids are properly stored and reusable containers are thoroughly cleaned as bacteria grow most heartily in sweet liquids.
Drinks that should be avoided are those that contain alcohol, caffeine, carbonation, and fruit juices. Alcohol and caffeine cause the kidneys to produce more urine, making dehydration worse. Make sure you are thinking ahead – don’t overindulge on these dehydrating drinks the day before being exposed to hot environments or heavy exercise. Start the day with a full tank. Carbonation can cause you to feel more full due to the release of carbon dioxide in the stomach reducing the amount of fluid you’ll drink and possibly causing cramping and discomfort during exercise. Soft drinks are both carbonated and have high carbohydrate concentrations. Fruit juices are typically well above the recommended 10% carbohydrate level. Salt tablets should never be used as they irritate the stomach and can easily send a person’s salt levels too high, which can also be life-threatening. Since the average diet contains well above the required amounts of sodium, salt tablets are never recommended.
Some
drinks
add
supplements as “energy enhancers.” These are
essentially all marketing
hype and
have not been shown to improve performance. Some additives can be
dangerous, if
not deadly. Ephedra has recently been removed from the
A
very
well-liked
drink that I call “Friar Galen’s Holy
Water” has been loved by fighters
at many
hot summer practices is made by slicing and squeezing a dozen lemons
and six
oranges into the ubiquitous 5-gallon water container. Add 2½
to
3 gallons of
water and a bag of ice. It’s more flavorful if it sets for a
few hours
before
adding the ice and serving. If you want to make it very close in
carbohydrate
and sodium content to Gatorade®,
add 3 cups
of sugar and
3 tsp of table salt to the basic mix. Based on 3 gallons of water this
mix will contain 6%
carbohydrate and 635
mg of
sodium per liter.
Don’t
let
the hype of
the drink companies get in the way of taking proper care of yourself or
your
SCA brethren. A drink that has the proper balance of nutrients does no
good if
no one will drink it. Pick a flavoring system that your local group
likes and
will drink plenty of and make sure everyone is staying adequately
hydrated. The
makers of the Camel Back® system got it
right when they
said:
“Hydrate or Die!”
References:
Armstrong,
Lawrence E.
Performing in Extreme Environments. Human Kinetics. 2000.
Bookspan,
Jolie.
Health & Fitness in Plain English, 2nd
Edition. Healthy
Learning. 2002.
Copyright © 2004 Galen of Ockham, MC, OP (MKA Keith E. Brandt, M.D., M.P.H.) May be used in SCA publications as long as content is not modified and proper credit given. For all other uses, please contact the author at galen@chirurgeon.org .
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