Hydration
1. How often do you hydrate?
2. What does hydration look like
for you?
3.What is the biggest challenge
in staying hydrated for you?
Water
• Most important nutrient
• Vital to living
• 75% of all muscle tissue & 25% of adipose tissue is made up of water
• How long can you live without food? How long can you live without
water?
• The human body can survive weeks without food, but most people can only
survive 2-4 days without water
• Too great a water loss is detrimental to performance and health
• Hydration must be individualized
Role of water in the body
• Regulate core temperature
• Dissolves minerals & other nutrients, increasing their bioavailability
• Lubricate joints
• Moisten tissues
• Eyes, mouth, nose
• Remove waste products
• Assists the kidneys & liver
• Remove metabolites
• CO2 binds to H2O to be exhaled from the ETC
• Enzymatic reactions
• ATP ADP + Pi
Terminology
Match these:
With these:
1.
Fluid balance
a)
Adequate water to meet physiological demands
2.
Euhydration
b) Excess water; considered temporary
3.
Hyperhydration
c)
4.
Hypohydration
d) Process of the body losing water volume
5.
Dehydration
e) Insufficient water volume
Considers water volume and solute concentration
Terminology Answers
1. Fluid balance: Considers water volume and solute concentration
2. Euhydration: Adequate water to meet physiological demands
3. Hyperhydration: Excess water, considered temporary
4. Hypohydration: Insufficient water volume
5. Dehydration: Process of the body losing water volume
Where is water
held in our
bodies?
• ~2/3 of body water is found in
the intracellular fluid
compartment
• Within cells
• ~1/3 is found in the
extracellular fluid
compartment
• Outside cells
Benefits of
being hydrated
• Helps maintain athletic
performance
• Helps with recovery
• Maintains mood
• Maximizes heat transfer
Effects of low water intake
• Low water intake drastically affects the body
• Linked with chronic kidney disease and diabetes
• Increase risk of UTI
• Impairs blood glucose regulation
• Impairs cognitive functioning
How Does the Body Lose Water?
Sensible
• Sweating
• Exercise
• Humid weather
• Individuality
• Urination
• Bowel movements
• Illness
• Fever (sweating)
• Diarrhea
• Vomiting
How much sweat
do you lose?
Sweat loss can vary considerably:
• ~100 ml daily in non-exercise,
temperate conditions
• 1 to 2 L/hr if exercising in high
temperatures with protective
clothing
• >2.5 L/hr in prolonged exercise
in the heat
• Cold environments, exhalation
Sweat and water loss
Osmosis
• Breathing
• Ventilation (Exhale & Inhaled Air)
• Transepidermal water loss
• Non-sweat diffusion through skin
• Affected by environmental and intrinsic factors
Dehydration
• Symptoms
• Extremely thirsty
• Fatigue and exhaustion
• Muscle cramps
• Headache, confusion, lightheaded, dizziness
• Dry eyes and mouth
• Prevention
• Be proactive
• Consume water pre, during, & post
Food or beverage
% Water
Predominant substances
Water
99
Some minerals depending on the hardness of
the water and traces of other compounds
Coffee or tea (black)
99
Some minerals depending on the hardness of
the water and traces of other compounds such
as caffeine
Sports beverages
90–94
Sugars
88
Sugars
Fruit juice
Milk
88–91
Protein, minerals, milk sugar, possibly fat
(depending on the
fat content)
Effects of Dehydration on Aerobic
Performance
Sport
Degree of dehydration*
Effect on performance
Basketball
2%
Movement slows, shooting is less accurate, and
attention declines; performance declines continue as
the degree of dehydration increases
Distance cycling
2.5%
On a 2-hour ride with hills, power output for hill
climbing declines
1,500 m run
2%
Running time increases by ∼3%
5,000 or 10,000 m run
2%
Running time increases by ∼5%
Soccer
1.5–2%
Playing ability and fitness declines; perceived
exertion increases
Wrestling
≥4%
Mental confusion
*Percent loss of body weight as water
How can you tell if
someone is hydrated?
Checking hydration
status
• Urine specific gravity (USG)
• Acute bodyweight changes
• 60 kg person has an acute loss of -1.4 kg
(1.4 kg/60 kg × 100%)
• 2.3% loss of water
Blood
composition
Calculating Daily Water Needs
1. Determine your weight
• Water intake requirements will vary according to body mass Direct
relationship
2. Multiply weight (lb) by 2/3 (0.67) to calculate daily water needs in
ounces
3. Determine additional needs from exercise
• Add an additional 12oz of water per day for every 30 minutes of exercise
• Higher needs for higher intensity exercise or in hot environments
4. Can convert to Liters by multiplying total ounces by 0.03
Practice Activity
A recreationally active female that weighs 60 kg is going for a 3-mile run,
that typically takes her 30 min.
She is running in a comfortable climate with low humidity. What is her daily
water needs and water needs this specific day?
1. Determine weight in lbs
• 60 kg x 2.2 = 132 lb
2. Multiply weight by 0.67 for daily water needs
• 132 lb x 0.67 = ~88 oz
3. Add ___ oz for exercise
• 12 oz (30 min exercise) + 88oz = 100 oz
4. Convert to Liters
• 100 oz x 0.03 = 3 L / day
Practice Activity
• You have a male marathon runner that weighs 75 kg
• After their race they weighed themselves and found they lost 2% of
their bodyweight during the race
• If every 2.2 lb a person loses equates to 1 L of fluid loss (sweat loss)…
• How many L of water should they aim to drink to restore their water
loss?
• 75 kg x 2.2 = 165 lb
• 165 lb x 0.02 (2%) = 3.3 lb
• 3.3 lb / 2.2 lb = 1.5 L of water
Conversions
• 1 Glass/Cup = ~8 oz
• 1 Liter = 34 oz
• 1 Gallon = 128 oz
• 1 Gallon = 4 L
• ~4, 8 oz bottles = 1 L
• 16, 8 oz bottles = 1 Gal
• 4, 1 L bottles = 1 Gal
Electrolytes Involved in Fluid Balance
Cations
Anions
Sodium (Na+)
Chloride (Cl−)
Potassium (K+)
Bicarbonate (HCO3−)
Calcium (Ca2+)
Phosphate (PO43−)
Magnesium (Mg2+)
Protein
• Cations = positively charged electrolytes
• Anions = negatively charged electrolytes
Sodium (Na⁺) & Chloride (Cl⁻)
Intake
Absorption & Output
• Food, beverages
• The body absorbs sodium into the small
intestine
• Use of saltshaker
• Salt tablets
• Cl⁻ same as Na⁺, but found as
‘sodium-chloride’ in foods &
beverages
Role
• Fluid balance
• Acid-base balance
• Action potential/nerve impulses
• Sweat, urine, feces
• Na⁺ loss in sweat is generally low but can be
substantial for some people
• Na⁺ output in urine is typically high because of
tight homeostatic control by the renal system
Potassium (K⁺)
Intake
• Found in food and beverages
• Occasionally the use of salt substitute
• Intake tends to be low due to lack of
fruits, vegetables, & minimally
processed foods
Role
• Maintain osmotic pressure:
• Acid-base balance
• Action potential/nerve impulses
Absorption & Output
• Dietary potassium is easily absorbed
into the small intestine
• Small losses in sweat or feces
• Losses in urine tightly controlled by
the renal system
• Atypical losses such as vomiting &
potassium-depleting diuretic drugs
can be dangerous
• ~160 mg of potassium is lost daily
Calcium (Ca⁺⁺)
Intake
• Food (both naturally occurring and fortified), beverages
•
Milk & dairy products
• Supplements
• Many people consume less than is recommended
Role
Absorption & Output
• Calcium is the most abundant mineral in the body
• ~10-30% of dietary calcium is absorbed into the small
intestine, mainly in the duodenum
• Primary function: build and maintain skeletal tissue
• 99% of the body's calcium supply resides in the bone and
teeth
• Small losses in sweat
• Required for the transmission of nerve impulses
• Blood calcium tightly regulated by several hormones, which
affect absorption, retention, & excretion
• Controls the flow of fluid through cell membranes
• Vital role in muscle contraction & relaxation
• Larger losses in feces (unabsorbed calcium) & urine
Resting Membrane Potential
Magnesium (Mg⁺⁺)
Intake
• Food, beverages
• Supplements
• Many people consume less than is
recommended
Role
• Involved in over 300 enzymatic reactions
• Involved in CHO metabolism as an
activator of enzymes
• Serves as a coenzyme in protein synthesis
& lipid metabolism
Absorption & Output
• Mg⁺⁺ is absorbed in the small intestine
• The amount absorbed depends on the
Mg⁺⁺ intake of the individual
• Small losses in sweat & feces
• Most Mg⁺⁺ is lost via urine
• Some diuretics increase urinary excretion
Roles of Magnesium (Mg⁺⁺) in the Body
• Magnesium is involved in over 300 enzymatic reactions
• Involved in CHO metabolism as an activator of enzymes for the initial
pathway for glucose oxidation
• Serves as a coenzyme in protein synthesis & lipid metabolism
Hydration Recommendations
Pre-Exercise Hydration
• Physically active individuals should maintain euhydration (1% to –1% change in body
weight) for optimal exercise performance
Pre- Goals:
• Being fully hydrated prior to exercise
• Avoiding gastrointestinal upset
• Consuming CHO, if appropriate
Amount Guided By:
• Anticipated intensity & duration of activity
• Potential effect of hypohydration on performance
• Environmental conditions
Guidelines before exercise
• Pre-exercise fluid consumption should begin 4 h prior
• 5-10 mL/kg in 2-4 h timeframe
• 1 oz = 30 mL
• 8 oz = 1 cup
• If hypohydrated, add another 3-5 mL/kg
• Tip: Pinch of salt in pre-exercise drink to stimulate thirst
During-Exercise Hydration
During Goals:
• Replace lost body water to best extent possible
• Slow dehydration to the extent possible
• Avoiding overconsumption of water
• Replacing sodium
• Consuming CHO if appropriate
• Avoiding GI distress
During exercise guidelines
• Prevent excessive (>2%) dehydration
• When guidelines can be established, aim for 0.4-0.8 L of fluid per
hour
• Individual sweat rate & sodium loss
Post-Exercise Hydration
Post- Goals:
• Restore lost body water
• Replacing sodium & other electrolytes
lost
• Consume CHO to replenish muscle
glycogen & water
• Consume protein
• Avoiding GI distress
Guidelines
• ~1–1.5 L (50 oz, or 6 cups) of fluid per
kg of body weight lost, as soon after
exercise as is practical
• 2.2 lb loss (1 kg) = 1 - 1.5 L rehydration
Developing a Plan for an Athlete
1. Assessment
• Assess hydration status
• Thirst, urine color, body weight
• Salt crystals on skin or clothing, salty
sweat taste, cramping
2. Goals
• Q’s to Ask:
• Is the athlete euhydrated?
• What is the athlete’s goals prior to
exercise?
• Goals during exercise?
• Goals after exercise?
Developing a Plan for an Athlete
3. Action Plan
• Guidelines are normally given as
ranges, so athlete has a range to
fall within
• Ex. 5-10 mL/kg prior to exercise
• Round decimal numbers to whole
numbers for the athlete
• Ex. Instead of 2.2 cups, recommend
2-3 cups
4. Educate
• At their level, teach athletes why it
is important they are aware of
hydration status and are cognizant
about staying hydrated
• Teach them how to read nutrition
labels and how to look for:
• Serving size
• Carbohydrates
• Sodium
• Other electrolytes
Practical Activity
• Find 2-3 friends
• You have a client who is a female soccer player that weighs 57 kg, she has a game this weekend that will last roughly
3 hrs
• Devise a plan for fluid &/or electrolyte intake before & during the game
•
How much of her daily water intake do you think she should drink before and during?
• Include any products from Table (next slide) that might be beneficial for this particular athlete
• Although she drank water and electrolytes throughout her game, she was 2 lb lighter after the game than before
• What % of bodyweight did she lose during the game?
• How much water should she drink through the remainder of the day to make up her water loss?
*Round your numbers
Make sure to consider:
•
The demands of the sport and the environmental conditions
•
Why an athlete might dislike the plan that you created
Answers
• Soccer Athlete Metrics
• Weight: 57 kg = 125 lbs
• Pre-Needs
• 57 x 5-10mL = 285-570mL
• / 30 (oz) = 10-20 oz
• During-Needs
• 0.4-0.8 L
• Daily Water Needs
• 125 lb x 0.67 = ~84 oz
• + Activity
• 12 oz x 6 (3 hrs) = 72 oz or ~2 L (1 L = 36 oz)
• Percentage of Water Loss
• 57 kg (euhydrated) has acute loss of 1 kg (2 / 2.2)
•
1 kg/57 kg × 100% = ~2%
• L of Water Needed Post-Exercise (1-1.5 per kg lost)
• 1-1.5 L (1 kg/2.2 lb = 1-1.5 L)
Questions?
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