This document provides key tips on hydration for different activities including studying, physical activity, traveling, sports, and the workplace. It emphasizes that adequate hydration is important for cognitive function and physical performance. When exercising or engaged in physical activity, it is important to drink fluids regularly to replace sweat losses. During travel, one should stay hydrated during flights due to dry air and when driving long distances in hot conditions. Sports guidelines recommend developing a personalized hydration plan based on sweat rate and opportunities to drink during training and competition. Workplace hydration is also important as working in warm conditions can result in significant sweat losses.

1.
Key Tips on Hydration (Volume 2)
Hydration needs for different activities
Index
• Key Tips on Hydration for studying.
• Key Tips on Hydration for physical activity
• Key Tips on Hydration for travelling.
• Key Tips on Hydration for sport.
• Key Tips on Hydration for the workplace.

2. Hydration while studying
KEY TIPS
ON HYDRATION For HeaLthcare Professional
distribution only
Dehydration can adversely influence cognitive function1,2
, and this is important when considering
tasks such as studying.
It has been observed that when mild dehydration occurs (i.e. when 2-4% of body water is lost).
In situations where less severe dehydration occurs (such as when refraining from drinking for a
relatively short period of time – up to a few hours), studies have generally failed to find evidence of
cognitive impairment2
.
Studies finding a relationship between dehydration and cognitive performance have to be interpreted
with caution to determine the effects of dehydration independently of the effects of other stressors
(e.g. thermal and physical stress, fatigue, etc.)3
.
Nevertheless, on the basis of the known physiological effects of dehydration in the brain, the stress
associated with dehydration itself could be considered a unique stressor with unique effects that may
or may not be similar to those of other stressors. This supports the notion that adequate hydration
status is of importance when facing cognitive tasks. The extent and duration of dehydration leading
to cognitive impairment, and the cognitive functions most affected remain to be investigated4
.
Adequate hydration
is important for optimal
functioning of the brain.
When an individual is well
hydrated, brain cells are
better supplied with fresh,
oxygen-laden blood, and
the brain remains alert.
Short-term memory,
can be impaired1
attention, and
arithmetic efficacy
Greater tiredness,
have also been reported2
reduced alertness, and
lower levels
of concentration

3. KEY TIPS ON HYDRATION
PRACTICAL TIPS TO STAY HYDRATED WHILE STUDYING
Before going to school, high-school or university, it is important to ensure that
hydration status is adequate: breakfast should include enough liquid to achieve
this. Two studies have demonstrated that children commonly start the day at school
partially dehydrated5,6
.
Water should be available throughout the day and drinks should be taken regularly
especially if the environment is warm.
Teachers may need to make sure that there are opportunities for drinking during
the school, high-school or university day and that students are reminded to make
use of these opportunities. Families should also be aware of this.
Special attention should be given to meal times because:
Eating helps to stimulate the thirst response causing the intake of additional
fluids and restoration of fluid balance7
.
Meals provide an important part of the water consumed during the day and it
should be remembered that of the water intake in the diet:
Educating pupils to assess their own hydration status can also be valuable* and urine
colour provides a useful estimate of the hydration status during everyday activities10
.
70-80%from beverages
(all types, not just plain water)2,9
20-30% typically comes from
food and about
However, this may vary greatly
depending of the diet that an
individual chooses.2,9
* See our educational material about how to measure hydration status at:
www.europeanhydrationinstitute.org/educational_materials.html
1. Gopinathan PM, Pichan G, Sharma VM. Arch Environ Health 1988;43:15-7. 2. Szinnai G, Schachinger H, Arnaud MJ, et al. Am J Physiol Regul Integr
Comp Physiol 2005;289:R275–R280. 3. Institute of Medicine: Dietary reference intakes for water, potassium, sodium, chloride, and sulfate. Washington,
DC: The National Academies Press, 2005. 4. Lieberman HR. J Am Coll Nutr. 2007;26(5 Suppl):555S-561S. 5. Bonnet F, Lepicard EM, Cathrin L, et al. Ann
Nutr Metab. 2012; 60(4):257-63. 6. Assael BM, Cipolli M, Meneghelli I, et al. J Nutr Disorders Ther 2012;2:3. 7. Maughan RJ, Leiper JB, Shirreffs SM.
Eur J Appl Physiol Occup Physiol 1996;73(3–4):317-25. 8. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary
reference values for water. EFSA Journal 2010; 8(3):1459. Available online: www.efsa.europa.eu/en/efsajournal/pub/1459.htm 9. Manz F, Johner SA,
Wentz A, et al. Br J Nutr 2012; 107(11):1673-81. 10. Kolasa KM, Lackey CJ, Grandjean AC. Nutrition Today 2009;44:190-201.

4. HYDRATION AND PHYSICAL ACTIVITY
KEY TIPS
ON HYDRATION
Physical work performance is usually decreased
when dehydration exceeds about 1-2% of body
weight2
:
• Prolonged exercise in the heat with dehydration
corresponding to a loss of only 1% of body
weight increases body temperature, which is
a consequence of both reduced sweating and
reduced skin blood flow induced by dehydration2
.
• A body water loss equivalent to more than about
2% of body mass induced by exercise in the heat
has been shown to impair performance in a
wide variety of tests of both physical and mental
performance3
.
For HeaLthcare Professional
distribution only
In general, it is necessary to drink during exercise
only when sweat losses are high enough to affect
performance or when exercise has begun in
a dehydrated state. During exercise, drinking
should occur regularly, but the frequency of
drinking and the amount consumed will depend
on many factors, including:
• intensity and duration of exercise
• weather conditions
• physical characteristics of the individual: body
weight and sweating characteristics.
Fluids consumed during exercise can play a
number of roles, including making one feel more
comfortable, replacing a body fluid deficit, and
providing a means to consume other ingredients.
Replenishing
liquids
sweat
LUNGS
URINE
FAECES
During prolonged physical activity, body water losses are primarily caused by sweat, although urine
and respiratory fluid losses also have an important contribution1
.

5. KEY TIPS ON HYDRATION
70-80%from beverages
(all types, not just plain water)4,5
20-30%typically comes from food and about
When it is helpful to drink during
exercise
• It is seldom necessary to drink during exercise that lasts less than about 40 minutes or when
intensity is low, provided that the hydration status was optimal at the start. Plain water or any
non-alcoholic beverage is perfectly adequate in these situations if something is needed.
• When the exercise lasts longer than about 30-40 minutes, sports drinks may be better than
water2
. One key benefit is that they can reduce the sensation of effort, making exercise seem
easier. Therefore, the individual will be more likely to enjoy the exercise program and more
likely to stick with it.
However, this may vary greatly depending on the diet that an individual chooses4,5
1. Casa DJ, Clarkson PM, Roberts WO. American College of Sports Medicine Roundtable on Hydration and Physical Activity: Consensus Statements
Current Sports Medicine Reports 2005, 4:115–127.
2. Fuji N, Honda Y, Hayashi K, Kondo N, Nishiyasu T. Effect of hypohydration on hypertermic hyperpnea and cutaneous vasodilation during exercise in
men. J Appl Physiol 2008;105(5):1509-18.
3. Cheuvront SN, Carter R, Sawka M. Fluid balance and endurance exercise performance. Curr Sports Med Rep 2003;2:202-8.
4. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary reference values for water. EFSA Journal 2010;
8(3):1459. Available online: www.efsa.europa.eu/en/efsajournal/pub/1459.htm.
5. Manz F, Johner SA, Wentz A, Boeing H, Remer T. Water balance throughout the adult lifespan in a German population. Br J Nutr 2011;1-9 [Epub
ahead of print].
In order to ensure an appropriate amount of water, it is important to take into
account that of the total water consumed, about:

6. SUMMER HOLIDAYS
KEY TIPS
ON HYDRATION
Don’t forget to
consider your
hydration needs.
In a temperate climate about 2-3 L of water
is lost from our bodies each day, mainly as
urine but also as sweat, expired breath, and
faeces.
The total amount of water lost will depend on several factors, such as gender, body size, the level of
physical activity and the amount and type of clothing worn. Environmentalconditionsoftemperature
and humidity will also have an impact on water loss.
Sweating or perspiring is a skin-cooling mechanism that uses a great deal of water. Water diffusion
through the skin accounts for about 0.45 L per day. However, environmental temperature and humidity,
the presence of air currents, the amount of clothing worn and the level of physical activity are all
factors that will influence the actual amount of water lost1
.
For Heathcare Professional
distribution only
Are you about
to go away
on holiday?
Sweat losses will be higher when exposed to high temperatures, such as in
the summer or in any other hot environment, and these must be replaced.
Hydration requirements need to be considered both, duringtravelling and in the holidaydestination.
When taking a plane
The body tends to dehydrate while travelling on aeroplanes because air in the cabin is dryer (10-20%
humidity) than a typical, comfortable indoor environment (30-60% humidity) and this is due to the air
conditioning. Under these conditions skin dehydration symptoms can be observed (parched lips, dry
eyes, itchy eyes, etc.) and increased amounts of water are lost through the breath. Mild dehydration
occurring during long flights is one of the causes of an increased blood viscosity, which in turn may
increase the risk of deep vein thrombosis2
.
When travelling by plane, hydration levels can be maintained by drinking an additional 250 mL of
water per hour over your regular hydration needs.

7. KEY TIPS ON HYDRATION
You can find information about how to recognize signs and symptoms of mild dehydration, and
practical advice about hydration during hot weather in our series of educational materials:
Key Tips on Hydration: recognizing signs and symptoms of mild dehydration.
www.europeanhydrationinstitute.org/files/EHI_Key_Tips_on_Hydration_Signs_and_symptoms_of_mild_dehydration.pdf
Key Tips on Hydration: hot weather
http://www.europeanhydrationinstitute.org/files/EHI_Key_Tips_on_Hydration_Hot_Weather.pdf
1. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary reference values for water. EFSA Journal 2010;
8(3):1459. Available online: www.efsa.europa.eu/en/efsajournal/pub/1459.htm 2. Hamada K, Doi T, Sakura M, Matsumoto K, Yanagisawa K, Suzuki
T, et al. Effects of Hydration on Fluid Balance and Lower-Extremity Blood Viscosity During Long Airplane Flights. JAMA 2002; 287: 844-5. 3. Manz F,
Johner SA, Wentz A, Boeing H, Remer T. Water balance throughout the adult lifespan in a German population. Br J Nutr 2012; 107(11):1673-81.
70-80%
from beverages (all types,
not just plain water)1,3
20-30%
typically comes from food and
It is calculated that of
the total water needed…
However, this may vary greatly
depending of the diet that an
individual chooses.1,3
If you travel by car
Driving in a hot car can lead to sweating with large losses of water and electrolytes. Even in an
air conditioned car, water losses can be high on a long drive. Maintaining adequate hydration
while driving is of great importance, because even with mild dehydration (loss of about1% of
body weight) reductions in physical and cognitive performance and in thermoregulation and
cardiovascular function can occur. With fluid deficits of 4%, more severe performance decrements
are observed as well as difficulties in concentration, headaches, irritability and sleepiness1
.
Frequent drinks of non-alcoholic beverages during a long automobile trip may help to reduce road
fatigue. The dryness caused by an air conditioning unit can be avoided by increasing the air’s moisture
levels and by hydrating the skin.
Have you checked the weather forecast at your destination?
It is important to keep an eye on the weather forecast, temperature and humidity in the city or region
you are visiting in order to adjust hydration levels accordingly.
SOME PRACTICAL ADVICE:
• Get to know your usual hydration needs and adjust them to the place you are visiting and the level
of activity you are planning.
• The hotter and more humid the weather is, and the higher the level of activity, the more water will
be needed. You can meet your hydration needs with a whole range of beverages and with food rich
in water. Take into account that:

8. Hydration for Sports
Performance: practical guidance
KEY TIPS
ON HYDRATION For HeaLthcare Professional
distribution only
1. Sport sessions should be started well hydrated. The aim is to develop fluid
practices over the day that keep pace with regular fluid needs as well as the
additional losses from exercise or hot environments. As losses change, so should
drinking practices. Fluid intake should be spread over the day.
2. A targeted drinking plan for training and competition should be developed. This
should be based on several pieces of information including individual sweat losses*,
the opportunities to drink, and feedback from individual feelings
of comfort and thirst. Sweat losses and the success of
the drinking plan during training sessions in different
situations should be monitored (see overleaf).
3. Watch out for “salty sweaters”, they may need drinks
with more salt and may need more salt in food when
sweat losses are high. To check whether someone is
a salty sweater, ask him/her to wear a black T-shirt in
training and look for salt stains (white powder) under the
arms and on the chest.
High salt losses may be a contributing factor in some
cases of muscle cramp. Sports drinks with higher salt
(sodium) levels (e.g. 300-500 mg sodium per 500 mL
liquid) may help reduce the risk of cramps for some
athletes.
Severe dehydration impairs performance and increases the risk of heat illness, but drinking
too much can also be harmful or uncomfortable. Every athlete is different because they have
different sweat losses and different opportunities to drink fluid during their workouts and events.
Every athlete needs a personal hydration plan and they have to play a
role in developing this.
The following are three simple steps that may help to guide hydration practices:
* Please consult www.europeanhydrationinstitute.org to find out how to estimate sweat losses and sweat rates.

9. KEY TIPS ON HYDRATION
* This should generally not exceed about 1-2% of body mass. If you lost more than this, you
probably did not drink enough, and you should drink more next time. If you lost less, you might
have drunk too much. Drinking so much that you gain weight during competition is seldom likely
to be a good idea. The only time you might need to do this is when you have been dehydrated at
the start of the event.
Please consult www.europeanhydrationinstitute.org for more information about hydration in
sports performance.
How to monitor sweat loSses
and the success of the drinking
plan during training sessions in
different situations.
Ask the people you are advising to consider the following questions every time they practice
sports in different situations in order to adjust water intake according to the answers:
• How did you feel?
• How did you perform?
• What was your weight
loss over the session?*
• Did it make you feel
uncomfortable?
• Did you take time out
to drink that was
unnecessary?

10. Hydration in the work place
KEY TIPS
ON HYDRATION For HeaLthcare Professional
distribution only
Water needs depend on gender and age but are also influenced by a variety of lifestyle factors; these
include the level of physical activity and environmental factors such as temperature, relative humidity
and air movement1
. Such variables can differ greatly from one working environment to another and
as many people spend a considerable percentage of their week at work, ensuring adequate hydration
in the workplace is an important consideration.
Working in a warm environment can result in substantial water losses from the body, mainly in the
form of sweat. The magnitude of such losses is dependent primarily on work intensity and duration,
although sweat rates can differ between various work activities and between individuals2
. Dehydration
may occur if water lost exceeds water consumption.
Hydration in the work place is a specific concern because dehydration can affect productivity, safety,
cost, and morale3
.
CONSEQUENCES OF DEHYDRATION
• Dehydration results in an increase in core temperature of about 0.1–0.2°C with
each 1% of dehydration4
.
• Dehydration can also increase the heart rate, which is typically accompanied by
an increase in an individual’s subjective rating of perceived exertion to perform
an exercise task3
.
• When dehydration exceeds about 2% of body weight, physical work capacity is
diminished5
.
• Dehydration has also been shown to adversely influence decision-making and
cognitive performance, which may contribute to a decline in productivity and
could be associated with an increased risk of work-related accidents3
.

11. KEY TIPS ON HYDRATION
PRACTICAL ADVICE TO STAY HYDRATED IN THE WORK PLACE
Preventing dehydration in the work place could involve a combination of strategies that
might include the following3
:
• Assessing hydration status*: urine colour provides a quick and useful estimate of
hydration state during everyday activities6
.
• Inclusion of practices that encourage fluid intake. Provision of water fountains and
vending machines may encourage workers to drink more often. Improving access to
bathroom facilities may also enhance liquid consumption, especially among women.
• Education: Informing individuals (especially those who work in hot environments)
about hydration assessment, signs and risks of dehydration, and strategies to maintain
hydration while working, can reduce dehydration in the workplace3
.
As well as encouraging fluid intake an education and hydration program at work should
stress the importance of consuming meals which include food rich in water, because:
- Meals play an important role in helping to stimulate the thirst response causing
the intake of additional fluids and restoration of fluid balance7
.
- It is calculated that of the total water consumed:
80%from beverages
(all types, not just plain water)1,8
.
20%
typically comes
from food
and about
However, this may vary greatly
depending of the diet that an
individual choices1,8
* See our educational material about how to measure hydration status at:
www.europeanhydrationinstitute.org/educational_materials.html
1. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary reference values for water. EFSA Journal 2010;
8(3):1459. Available online: www.efsa.europa.eu/en/efsajournal/pub/1459.htm 2. Sawka MN, Wenger CB, Pandolf KB. In Fregly MJ and Blatteis CM
(eds): Handbook of Physiology, New York: Oxford University Press, pp. 157–185, 1996. 3. Kenefick RW, Sawka M. J Am Coll Nutr 2007;26:597S-603S.
4. Sawka MN, Francesconi RP, Young AJ, Pandolf KB. JAMA 1984;252:1165-9. 5. Institute of Medicine: Dietary reference intakes for water, potassium,
sodium, chloride, and sulfate. Washington, DC: The National Academies Press, 2005. 6. Kolasa KM, Lackey CJ, Grandjean AC. Nutrition Today
2009;44:190-201. 7. Maughan RJ, Leiper JB, Shirreffs SM. Eur J Appl Physiol Occup Physiol 1996;73(3–4):317-25. 8. Manz F, Johner SA, Wentz A,
Boeing H, Remer T. Br J Nutr 2012; 107(11):1673-81.

12.
http://www.europeanhydrationinstitute.org/