Urine colour chart could help athletes and hikers avoid dehydration

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Urine colour chart could help athletes and hikers avoid dehydration

IRA DREYFUSS

Canadian Press

Monday, September 03, 2001

WASHINGTON (AP) - Researchers have developed a colour chart for urine with

hopes it will help athletes and hikers avoid dangerous dehydration. The

eight-colour strip is based on the darkening that urine undergoes as the

amount of water in the body decreases and the pigmented waste material

becomes more concentrated.

Chart colours range from very pale yellow to brownish-green. The lighter

three colours indicate a person is well-hydrated; four through six are

tolerable levels, and seven and eight are signs of dehydration. Matching the

urine colour to the chart displays the level of risk, the researchers said.

Casa, Lawrence Armstrong and their colleagues at the University of

Connecticut pioneered the colour strip approach and field-tested the system

on trail runners and mountain bikers. The data on trail runners were

presented in June at a meeting of the National Athletic Trainers'

Association; data on the bikers were presented in May at a meeting of the

American College of Sports Medicine.

In the experiments on trail runners, 16 highly trained distance runners were

tested during runs of about 90 minutes at what each runner considered a

comfortable pace. The tests were done during the summer in the wooded Blue

Ridge hills of Berry College in northwestern Georgia. Temperatures averaged

31 degrees and humidity ranged from 60 to 70 per cent.

Researchers examined each of the runner's urine just before the start of the

run, at the midpoint, and at the end. Among the tests was a specific gravity

analysis to determine the concentration of chemicals such as proteins and

minerals in the urine, so those results could be compared to findings made

by using the color charts.

The results were highly correlated - for instance, dark-colour matches on

the charts came from runners whose urine had high concentrations of proteins

and minerals. The bikers' paces were more intense, but they also yielded

close matches.

The tests show the system can be used in real-world outdoor circumstances,

Casa said. The scientists previously had validated their colour chart

approach only in controlled laboratory testing, he said.

Exercisers in hot weather need to pay close attention to hydration because

they can lose two litres of fluid an hour just by sweating. Besides cutting

into performance, dehydration can result in heat exhaustion and potentially

a fatal heat stroke. Using a colour chart reminds a person to drink, Casa

said.

The strips are not for everybody, but they have their uses, said Dr.

Resnick, a urologist at Case Western Reserve University/University

Hospitals, Cleveland, who was not connected with Casa's work.

People who are prone to kidney stones could use them, especially if these

people exercise in hot weather, because concentration of minerals in the

urine raises the risk of kidney stones, Resnick said. Colour strips might be

valuable for athletes whose strenuous exercise raises the risk of

dehydration, but healthy exercisers whose activity is less strenuous don't

need to pay such close attention, he said.

Dr. Otten of the University of Cincinnati, who also was not connected

to the colour strip studies, offered a simpler test.

" If it looks like water, and you're drinking water, it's good, " Otten said.

" Lemonade (colour) is OK. If it looks like apple juice, you need to drink

more water. If it looks like Coca-Cola, you need to go to the nearest

hospital. "

Very dark urine indicates the body is breaking down muscle protein, a

condition that can lead to fatal kidney damage, Otten said.

Watching what is released is important, but not as important as paying

attention to what goes in, said physiologist Greenleaf of NASA Ames

Research Center at Moffett Field, Calif. Greenleaf studies how astronauts'

fluid levels vary in response to weightlessness.

On Earth, people sweat away water literally before they know it - the

sensation of thirst lags behind the loss of fluid. And people find it hard

to drink as much as they need. Greenleaf's rule of thumb is to drink 50 per

cent more than the person feels like drinking.

© Copyright 2001 The Canadian Press