chap 7 (water) Flashcards
factor affecting body water content
body size, gender, age, body composition
average body water amount male and female
42 L male, 30 L female
where is most of the water in the body located
intracellular water
place the water location in the body in order from lower to higher
plasma, interstitial fluid, extracellular water, intracellular water
how does the water moves in the body and must pass through what
by hydrostatic and osmotic pressure -> must past trop ECF into ICF
what is hydrostatic pressure + used by what
difference in fluid pressure between two area -> water. in blood plasma (higher pressure) to interstitial space (lower pressure)
cardiovasculaire system to move blood
Water moves from an area of
higher/lower solute concentration to an
area of higher/lower solute
concentration.
lower to higher
There are two major aspects to fluid balance that must
be considered and understood:
water volume and concentration
what act as a gateway for water entry into the body
ECF
what does hypotonic means
having a lower osmotic pressure than another fluid
what is the major cation in extracellular fluid
sodium
what is osmosis
tendance of water to move from areas of low solute concentration to area of high solute concentration
what are the different source of water
fluid consumption - 80%
food: < 20%
cellular metabolism
avenue of water loss
urination (60%)
defecation
sweating (90%)
breathing
what is the major cause of water loss
sweating
sodium is excreted by
kidneys
processed foods is high in Na or K
Na
unprocessed food is abundant of Na or K
K
low intake of potassium reflect what
lack of fruit and vegetables
what is hyperkalemia and can result from + symptom
too munch potassium intake -> from supplementation
muscle fatigue, weakness, paralysis, arrhythmias, difficulty breathing
what is hypokalemia, cause and symptom
sustantional potassium loss -> misuse of potassium-containing diuretic, frequent self-induced vomiting, prolonged diarrhea
increase BP, bone turnover, muscle weakness, arrhythmia
K excretion is regulated by
renal system
The three major areas of sensible water loss are the
fluid lost in feces, urine, and sweat
exemple of food with a high potassium content
banana, orange juice, avocados
what is the adequate intake of potassium for adult
4700 mg
Hypokalemia, a severe deficiency state, is de-
fined as a blood potassium concentration less than
3.5 mmol/L
Athletes who are concerned about the potential for a moderate potassium deficiency should focus on consuming a variety of
fruit and vegetable
where does heat go during exercise
sweat gland are stimulated to secrete sweat and reduce heat load -> when sweat evaporates, heat is transported away from the body
for every L of metabolic energy how many kcal is converted in heat and energy
4 kcal in heat, 1 kcal in energy
influential factor of sweating
- exercise intensity and duration
- environmental conditions
- clothing
- training statue
Aerobic exercise training improves thermoregulation via:
- increase blood volume
- increase skin blood flow capacity
- increase sweat glands
- Earlier onset of sweating
- increase sweat rate at a given core temperature
what happen if we exercise without fluid intake
- progressive dehydration during exercise
- hyperthermia & earlier onset of fatigue
- increase risk of cramp & heat illness
recommendation for heat acclimation
- Repeated training in the heat
- Acclimatization >60 min/d with é body core & skin temp, and stimulate sweating
- Train in same environment as competition
- Start >2 weeks (early adaptations w/i days, main physiological adaptations in 7 days)
- Follow hydration guidelines
- Consider external and internal
cooling strategies
amount of sweat loss during exercise
- 100ml daily in non exercise
- 1 to 2 L/h in high Tº
- > 2.5h in prolonged exercise in heat
loss of _% of body weight in water is common
2-7%
how munch body water loss will result in decreased endurance performance
> 2%
_ endurance athletes fatigue more quickly when exercising in the heat than a _ endurance athlete
hypohydrated, euhydrated
Ambient temperatures, decrease VO2max with fluid loss _% BW
> 3%
High temperatures, decrease VO2max with fluid loss _% BW
> 2%
in strength and power athletes, there’s no change in anaerobic performance or muscular strength with fluid loss _% BW
<3-5%
REASONS THAT DEHYDRATION CAN
NEGATIVELY AFFECT PERFORMANCE
- decrease BV
- decrease blood flow
- D sweat rate
- I core Tº
- I rate of muscle glycogen use
_ main electrolyte loss in sweat
Na
what happen with Na and CI reaborsptlon in light and heavy sweating
light: reabsorbe in tubule of sweat gland
heavy: not reabsorbe
if athlete train >2h do they need Na supplementation
yes
what is hyponatremia + effect
low blood sodium, can impair neural and muscular functioning
other name for hyponatremia
water intoxication
how can hyponatremia occurs
hyperhydration and extensive sweating
what can result from hyperhydration
hyponatremia
how to monitor hydratation status
weight loss, thirst, urine color
how munch water lost is associated with 1 kg lost in body weight
1 L = 1 kg
hydration strategies before exercise
if adequately hydrated
slow intake of fluids, 5-10ml/kg at least 4h prior
if not
5-10ml/kg 4h prior + 3-5 ml/kg 2h prior
glycerol loading regime
1.2 glycerol/kg BW
26ml water/kg BW
60-90min
glycerol loading allow what
water storage prior to exercise
temporary adverse effect of glycerol loading
temporary weight gain, gastrointestinal upset
goal of water intake during training and performance
¡ Replace lost body water
¡ Slowing dehydration to the extent possible
¡ Avoiding overconsuming of water and other hypotonic fluids
¡ Replacing sodium if losses are large or rapid
¡ Consuming carbohydrate if appropriate
¡ Avoiding gastrointestinal upset
what is the consideration in setting and individualized plan for water
¡ Sweat rate
¡ Composition of sweat
¡ Duration of exercise
¡ Clothing
¡ Environmental conditions
¡ Potential dangers of water
overconsumption and
hyponatremia
how munch fluid should be consumed during exercise
Athletes should aim for matching their sweat & urine output with fluid consumption to prevent dehydration >2% reduction in body weight
how munch fluid should be consumed during marathon
0.4-0.8 L/h Na replacement if exercise >2h
FACTORS AFFECTING FLUID CONSUMPTION &
ABSORPTION DURING EXERCISE
Volume of Fluid Ingested
¡ Amount of Carbohydrate
60-66 g/h
¡ Carbohydrate Concentration
6-8% (to get rec. CHO amount drink ~1L)
¡ Type of Carbohydrate
Glucose or mixed
¡ Taste (Flavor)
may increase intake
Based on preference
¡ Exercise Intensity
[CHO]<7% best tolerated at higher intensities
environnemental conditions -> altitude increase fluid need
electrolyte
osmolality
Tº of beverage
protein
which one between fluid an Na is the priority that affected fluid consumption during exercise
fluid
ideal Tº of beverage to promote absorption
10-15ºC
Goal of Determining Individual Sweat Rates:
Establish a fluid plan that closely matches fluid intake with fluid losses.
REPLENISHMENT AFTER TRAINING AND PERFORMANCE
- Restoring lost body water to achieve
euhydration. - Replace sodium and other lost
electrolytes. - Consuming adequate carbohydrate to
restore muscle glycogen. - Consume protein to build and repair
skeletal muscle. - Avoid gastrointestinal upset.
how fluid should be consumed after exercise
> or= 150% (1.5 L/kg) weight loss within 6h post exercise
caution of fluid intake after exercise
avoid drinking large quantities of water -> decreases sodium osmolality + increase urine production
conséquence: delayed rehydration + hyponatremia
The ideal beverage for postexercise replenishment contains:
¡ Carbohydrates
Restore muscle glycogen.
Can increase the rate of intestinal absorption of both water & sodium.
¡ Sodium
Restores electrolyte balance.
Enhances fluid retention & the drive to drink.
¡ Water
Restores euhydration.
what type of fluids should be consumed after exercise
fluid containing CHO -> help fluid absorption
why is it important to have CHO in fluid consumed after exercise
if H20 only = decrease plasma Na & plasma osmolality = decrease stimulation to drink + increase urine output = delayed rehydration
recommendation for Na consumption after excise
300-700 mg sodium/L of fluid lost in sweat.
L = 34 oz = ~ 1.5-2.0 lbs of weight loss.
when to start rehydration
immedialty or <2h
Beverages and/or foods consumed after exercise should contain
carbs and Na
In which compartment is the largest
amount of body fluid stored?
intracellular fluid
The primary cation in extracellular fluid is:
a. sodium. c. calcium.
b. potassium. d. chloride.
a
Having a normal or optimal amount of
water in the body, sufficient to support fluid balance and meet required physiological functions, would be termed:
a. hypohydration c. euhydration
b. hyperhydration d. dehydration
c
Which of the following electrolytes might
be deficient in the diet of a person from an industrialized country (for example, the United States)?
a. sodium c. chloride
b. potassium d. phosphorus
b
Wearing uniforms and protective gear
while exercising in the heat typically:
a. keeps the sun off the skin and prevents body
temperature from rising.
b. restricts the evaporation of sweat and results in body temperature rising.
c. has little effect on body temperature.
b
A person exercising in a hot and humid
environment might lose how much fluid through sweating?
1 to 2 L/h
Water only is an appropriate pre-exercise
beverage for:
a. exercise lasting less than 60 minutes.
b. exercise lasting from 1 to 4 hours.
c. exercise lasting greater than 4 hours.
d. exercise lasting from 1 to 4 hours or greater
than 4 hours.
a
Two factors that may be associated with
hyponatremia include:
a. large losses of sodium in sweat and low water intake.
b. large losses of sodium in sweat and excessive
water intake.
c. intake of salt tablets and low water intake.
d. intake of salt tablets and excessive water
intake.
b
