Fluid, Electrolytes, And Exercise Flashcards by Brandon Focer

What is water’s role in the body?

Solvent, Solute, Reactant, Product, Carrier, Lubricant, Shock absorber, Coolant, Catalyst, Ionizing agent, Messenger, Controller

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What are water’s unique properties?

High heat capacity
High thermal conductivity
The above 2 help keep the body from overheating

High latent heat of evaporation

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In thermoneutral conditions, what is body fluid balanced maintained at?

0.2% of total body weight

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How is fluid lost?

Urine, feces, sweat, respiration, and transcutaneous water loss

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What 2 receptors help maintain hydration?

Hypothalamic osmoreceptors - gauge the osmolality of the blood
Vascular baroreceptors - gauge the pressure within major vessels

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What is osmolality?

Concentration of particles dissolved in fluid

High - dehydration
Normal - euhydration
Low - overhydration

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What is vasopressin?

Antidiuretic hormone - increases water reabsorption

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Where is vasopressin released from?

Pituitary gland

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What does renin do and where is it released from?

Controls the production of aldosterone

Kidneys

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What does aldosterone do?

Helps manage blood pressure

Retains sodium

Loses potassium

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What is angiotensin II?

Helps regulate blood pressure by constricting (narrowing) blood vessels

Triggers sensation of thirst and desire for salt intake via hypothalamus

Stimulates release of vasopressin

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Factors that affect fluid status

Body size
Body composition
Physical activity
Environmental (temperature, altitude, humidity)

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What is the DRI recommendations for water intake?

Males - 3.7 L/day (130 oz) or 16 cups
Females - 2.7 L/day (95 oz) or 12 cups

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What is the daily percentage of fluid consumed by food and beverages?

Food - 20%
Beverages - 80%

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What two minerals are found in the greatest concentration of sweat?

Sodium and chloride

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Symptom of large salt losses in sweat

Dry, white residue on the skin and clothing after sweat dries

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Health risks of large sodium chloride losses

Heat-related problems
Hyponatremia
Muscle cramps

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Hydration recommendations pre exercise
Both answers

5-10 ml/kg of body weight 2-4 hours before

2 hours before: 16-24 oz

15 minutes before: 8-16 oz

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Hydration recommendations during exercise:

General
High intensity (30-75 minutes)
Endurance and intermittent, high intensity (1-2 hours)
Endurance (2-3 hours)
Endurance (>/=) 2.5 hours)

Typically depends on sweat rate

General guideline: 0.4-0.8 L/hr

High intensity (30-75 minutes): 6-12 oz of water every 15 minutes (plus carbs and electrolytes as needed)

Endurance and intermittent, high intensity (1-2 hours): 6-12 oz of water every 15 minutes plus carbs (and electrolytes as needed)

Endurance (2-3 hours): 6-12 oz of water every 15 minutes plus carbs (and electrolytes as needed)

Endurance (>/=) 2.5 hours): 6-12 oz of water every 15 minutes plus carbs (and electrolytes as needed; may also be beneficial to add small amounts of protein)

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Hydration recommendations after exercise

Drink 1.25-1.5 L for every 1 kg of body weight lost

Benefits of adequate fluid intake on heart rate, stroke volume, cardiac output, skin blood flow, core temperature, perceived exertion, performance

Heart rate Lower
Stroke volume Higher
Cardiac output Higher
Skin blood flow Higher
Core temperature Lower
Perceived exertion Lower
Performance Better

What is the most biologically active molecule in the body

Water

An appetite for what minerals exist

Sodium chloride, but not for any other minerals

What percent of body weight change is considered excessive regarding hydration status

> 2%

What sweat glands are responsible for secreting sweat during exercise and heat exposure and are part of the thermoregulatory response

Eccrine

Total volume of fluid loss is based on

Environmental conditions Size (surface area) of individual Metabolic rate Physical activity Sweat loss Composition of diet Volume of excreted fluids

Why is water loss high during cold temperatures

The air inhaled during cold weather activity contains relatively little water vapor, so as it is warmed and humidified during its transit through the respiratory tract, additional water loss occurs

What is the minimum daily water need for a completely sedentary individual and what is the requirement in most minimally active individuals

Sedentary: No less than 1 L/day Minimally active: 3-4 L/day

Average water loss per hour of most athletes

1-2 L/hr

Ingesting an extra 3g of sodium requires how much additional fluid intake

1 L

How much water is required to excrete the urea produced from 100 G protein

700 mL

How much fluid is required to oxidize 100 kcal of carbs, protein, and fat

Carbs: 15 mls Protein: 13 mls Fat: 9 mls

Three reasons why thirst is an unreliable regulator of fluid needs during exercise

Behavioral - signals can be easily missed or disregarded due to distractions Fluid may not be readily available Physiological - osmolality must reach a certain point to trigger thirst

What is the average level of thirst threshold for people

290-295 mOsm/kg

How much sweat needs to be lost for electrolyte intake to become important

Greater 4 L

Sensation of thirst is a function of what

Changes in plasma sodium concentrations (plasma osmolality) and of changes in blood volume Drinking plain water removes the osmotic drive to drink (by quickly diluting the sodium concentration of the blood) and reduces the volume dependent drive (by partially restoring blood volume), causing the premature satiation of thirst Plasma sodium decreases Blood volume increases

Why is it unwise to recommend glycerol induced hydration

Athletes pay a metabolic cost for carrying around extra weight No compelling evidence it causes any physiological benefit Side effects Can possibly cause hyponatremia Banned for the World Anti-Doping Agency (may mask doping)

Why to avoid consuming a sports drink that contains more than 6-7% carbohydrates

Decrease the rate of gastric emptying Decreases the rate of fluid absorption

How much sodium is lost per hour during exercise

50 mEq/L or 1 g/hr

List the added benefits of consuming sodium in a rehydration drink

Stimulating athletes to drink more Palatability Reduces urination to help maintain blood volume

List the several different mechanisms of cooling and which ones are more prevalent in adults and children

Radiation, Evaporative, Conductive, and Convective Adults: evaporative/sweating Children: radiative and conductive

At what temperature is fluid most lost from urine or sweat

Urine: 68F Sweat: 85F

What is the amount of weight lost and physical effect of the below dehydration percentages 1% 3% 5% 7% 10%

1.5# - increased body temperature 4.5# - impaired performance 7.5# - GI problems, Heat exhaustion 10.5# - hallucinations 15# - circulatory collapse

Losing more than 2% of body weight from dehydration may result in

Early fatigue Difficulty making decisions Difficulty determining the best play Difficulty communicating with teammates

Why would an athlete’s fluid needs be increased in altitude training

Increase diuresis Expanding blood volume

How often should a well hydrated athlete urinate daily

Every 2-4 hours

Typical sports drink breakdown

15 g carbs/8 oz 110 mg/8 oz

Negative effects of consuming alcohol

Diuretic At risk for dehydration, heat illness, and cramping Suppresses fat use as a fuel during exercise Interferes with post-exercise recovery by delaying carb repletion and muscle recovery Increases risk for micronutrient deficiencies and adds empty calories Decreases restful and restorative sleep

What are the fluid, carbohydrate, electrolyte, and protein recommendations for the below activities High intensity activity (30-75 minutes) Endurance and intermittent, high intensity (1-2 hours) Endurance (2-3 hours) Endurance (>/= 2.5 hours)

High intensity activity (30-75 minutes): 6-12 oz/15 minutes (plus carbs and electrolytes as needed when > 1 hour) Endurance and intermittent, high intensity (1-2 hours): 6-12 oz/15 minutes plus carbs (and electrolytes as needed) Endurance (2-3 hours): 6-12 oz/15 minutes plus carbs (and electrolytes as needed) Endurance (>/= 2.5 hours): 6-12 oz/15 minutes plus carbs (and electrolytes as needed; may also benefit to add small amounts of protein)