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Body
Fluid Monitoring Guide |
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Introduction
To monitor sweat/fluid loss during
exercise and physical activities may help to maintain an optimal level
of exercise performance, help to avoid adverse effects of dehydration,
and reduce the risk of thermal injury.
The Hydra-Alerttm™ Series with Fluid Check™ is the ideal tool
for monitoring and reporting on the rate of dehydration during any physical
activity. |
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Significance
of monitoring sweat/fluid loss |
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- Avoid inadequate fluid replacement
- Maintain proper fluid volume in healthy humans
- Prevent heat exhaustion, or even death
- Reducing the risk of thermal injury
- Increase exercise duration to the highest efficiency
- Improve quality of workouts
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The
American College of Sports Medicine (1996) recommends "to minimize
the potential for thermal injury, it is advocated that water losses due
to sweating during exercise be replaced at a rate equal to the sweat rate."
Research seems to be unclear regarding recommendation of fluid replacement.
The danger of over consumption of fluids is with stomach discomfort and
hyponatremia that can result with over-consumption of fluids. It is well
documented that researchers agree fluid replacement should at least cover
losses on the scale, and that there is evidence that fluid replacement
in excess of this amount may be warranted. |
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Nationwide fluid consumption
surveys indicate that a portion of the population may be chronically mildly
dehydrated
CHICAGO, Sept. 2000- Americans
are working out and staying active more today than ever before. Although
people are aspiring to live healthy lifestyles , a majority is not properly
hydrating their bodies, causing them to feel tired, edgy, slightly headachy
and eventually thirsty. According to a popular sport drink company's survey
; chronic dehydration may be a result of several factors. The most alarming
is lack of knowledge.
Of the 500 active people surveyed, four our of five (79%) thought that
the recommended servings of fluid per day was 8-10 cups (8oz servings).
While that's OK when someone isn't working out, current research shows
that the recommendation can easily jump to 10 to working out, and can
easily jump to 10 to 12 cups per day when someone is active or working
out.
The majority of active people surveyed were not drinking the recommended
amount. Nearly two-thirds of respondents (62%) drink 10 or fewer servings
of fluid a day. Although 80% of the respondents were aware that caffeinated
beverages were dehydrating, they consumed a daily average of nearly three
8oz servings of caffeinated beverages, such as coffee, tea or soft drinks.
This means that one-fourth of the beverages that respondents consumed
are dehydrating beverages.
In addition to causing fatigue and headaches, dehydration can affect a
person's workout. Research shows that as little a 2% loss in fluids through
dehydration can cause endurance performance to drop by 6-7 percent. According
to a Journal of Sports Science study, dehydrated exercisers fatigued almost
25% sooner than those who stayed hydrated before and during workouts. |
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Strength
and Dehydration
Dehydration at levels as low
as 1.55 % total body weight can significantly reduce maximal strength.
Strength decreases due to dehydration range from 3-11%. However, the
majority of studies do not demonstrate a significant decrease in strength
due to dehydration. The amount of dehydration may not influence the
amount of strength reduction. The frequency with which strength reduction
occurs may increase with greater amounts of dehydration.
Endurance
and Dehydration
Dehydration reduces maximal
aerobic power and endurance performance. The greater the dehydration
the greater the decrements in performance. A loss of 3% of body weight
(170lb=5lbs=80oz/2.4liters, in medium to high human athletic output
this loss can occur in as little as 60 minutes or less depending on
ambient air temperature and humidity and body power output) by dehydration
may be a threshold level resulting in little or no decrease in maximal
aerobic power when less than 3% total body weight is lost, but significant
decreases in maximal aerobic power when greater than 3% of total body
weight is lost. Decreases in performance are increased in a hot environment
compared to temperate environment with the same amount of hydration.
The decreases in performance are associated with: |
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- Decreases
in cardiac output
- Increased
body temperature
- Increased
heart rate
- Increased
perceived exertion
- Possibly
increase reliance on carbohydrate as a fuel
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How dehydration is induced does influence the amount of decrement in performance,
because diuretics and exposure to sauna result in greater losses of plasma
volume than exercise. This makes associating a certain amount of dehydration
with a certain loss of aerobic power or performance difficult. |
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Symptoms
of Body Fluid Loss |
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Body
Fluid Loss (%) |
Body
Fluid Loss (oz) |
Symptons
(for 160 pound person) |
0.5
% |
13
oz |
Thirst |
2.0
% |
51
oz |
Strong
thirst, vague discomfort, loss of appetite |
3.0
% |
76
oz |
Increasing
hemoconcentration, dry mouth, reduced urine output |
4.0
% |
102
oz |
Increased
effort for exercise, flushed skin, impatience |
5.0
% |
128
oz |
Difficulty
in concentrating |
6.0
% |
153
oz |
Impairment
in exercise temperature regulation, increased heart rate |
8.0
% |
204
oz |
Dizziness,
labored breathing, mental confusion |
10.0
% |
256
oz |
Incapacitated,
delirium, swollen tongue |
11.0
% |
281
oz |
Renal
failure, death close |
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Fluid
Check weight Loss percentage
Assumes individual was fully
hydrated at the start :
- 1% weight loss
Replace fluid or a Decrease in endurance capacity
and aerobic performance may occur
(Sawak, Montain, and Latzka 1996; sawka, and Pandolf 1990)
- 2% weight loss
Decrease in endurance work capacity and endurance performance, possible
decrease in peak oxygen consumption, especially in hot / humid environments
(Barr 1999 ; Armstrong 1992; Wilmore and Costill p 470-471 1999)
- 3% weight loss
Decrease in endurance performance imminent, especially in hot/humid
environments
(Sawak, Montain , and Latzka 1996)
- 4%
weight loss
Large decrease in endurance performance and peak ozygen consumption,
especially in hot/humid environments (Wilmore and Costill p 470-471
1999)
- 5% weight loss
Possible muscle cramps, heat exhaustion possibly imminent, large decrease
in endurance performance and peak oxygen consumption, especially in
hot/humid environments. (ACSM 1995 ; Bucci 1994)
- 6% weight loss
Possible heat exhaustion, heat stroke, hyperthermia, coma, and even
death
(ACSM 1995 ; Bucci 1994)
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References
Information is drawn from many
references, references beneath each point
directly support the particular point.
References : ACSM Position stand : Heat and cold illnesses during distance
running.
Medicine and Science in Sports and Exercise 28 ( 12 ) ; I-x, 1995.
Armstrong, L.E. Keeping Your cool In Barcelona.1992
Barr, S.I. Effects of dehydration on exercise performance. Canadian Journal
of Applied Physiology 24: 164-172, 1999.
Bucci
, L.R> Chapter 14 Nutritional Ergogenic Aids. Nutrition in Exercise
and Sport. CRC Press 1994.
Sawka,
M.N., and Pandolf, K.B. Effects of body water losson physiological function
and exercise performance. Perspectives in Exercise Science and sports
Medicine. Brown and Bench Mark 1990.
Sawka,
M.N. , Montain, S.J., and Latzka, W.A. Body fluid balance during exercise-heat
exposure. Body Fluid Balance in Exercise and Sport, CRC Press. 1996.
Wilomore, J.H., and Costill, D.L. Physiology of Sport and Exercise. Human
Kinetics. p470-471, 1999. |
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