Ch 11: Hydration Flashcards by Troy Selby

Purposes of Water

Constitutes a great percentage of Body Mass
Helps fill the spaces inside and outside the cells
Continually being formed and broken down during metabolic pathways in the body
Found in all major vessels

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Water contained inside the cell membrane; Makes up 2/3 of the body’s water

Intracellular Fluid

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Water outside of the cell; b/w the cells and transported throughout the body via veins, arteries and capillaries.

Extracellular Fluid

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Primary factor that determines what space body water will occupy

Sodium and Potassium

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Major Extracellular Solute

Sodium

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Major Intracellular Solute

Potassium

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Molecules that contain a Positive or Negative Charge

Electrolyte

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Describes the concentration of Solutes in a Liquid

Osmolality

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Primary Regulator of Hydration Status

Osmolality of ECF (specifically Plasma Osmolality)

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Cause of the majority of fluid and electrolyte shifts in the body and between compartments

Food and Beverage Intake
Urine Loss during Recovery
Sweat during Exercise

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Physiological factors such as high Osmolality or Low Blood Pressure, which prompt Sodium and Water appetite

Dipsogenic Signal

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Specialized nerves that can sense change in pressure in the heart and blood vessels

Baroreceptors

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Most significant influence to thirst for water

Regulated by ECF Osmolality

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A solution with a Lesser concentration of Solute (Fresh water vs Salt water)

Hypo-Osmotic (Sweat)

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Key Driver of thirst

Plasma Osmolality

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The rate at which fluids and their contents pass through the stomach via the pyloric sphincter and into the small intestine

Gastric Emptying Rate (GER)

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Hydration efficiency was calculated as the volume of urine produced over a 4-hour period following ingestion of 1 liter of each beverage type

Beverage Hydration Index

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Best defense against experiencing a heat-related illness

Abstention from overexertion in hot external environmental conditions or microenvironments

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Key adaptations that improve tolerance to exercise in hot environments.

An earlier onset of sweating and greater sweat rate

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The movement or flow of air over an object

Convection (Wind, movement against air)

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Normal Hydration status

Euhydration

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Determinants of Sweat Evaporation Rate

Heat (higher temps increase rate of sweat evaporation)
Humidity (Environments with lower humidity increase the rate of sweat evaporation)
Convection

Factors involved in Heat Illness/stroke

Hydration
Environmental Conditions
Level of Exertion
Training Status
Body Composition
Clothing

Effects of Hydration status on Exercise Performance

Cardiovascular and Thermoregulatory Function

“as desired” and refers to eating or drinking as you are normally driven to (i.e., not purposely overeating or undereating).

Ad Libitum

Clinical Dehydration is defined by what?

Plasma Osmolality of Sodium, not by total body water

In the Laboratory, how is Euhydration defined

urine solute concentration (e.g., urine-specific gravity)

Hydration plan 3 steps

Establish Sweat Loss Volume from routine exercise sessions and determining if clients begin training in a Euhydrated status Once this information is established, Fluid prescription during and between exercise bouts can be developed

What do you need to determine client sweat rate?

A reliable digital scale. Clients should weigh themselves nude. Client should weigh themselves before and after the workout. Workout should last an hour. Avoid using the restroom

Fluid Intake should not exceed

Sweat loss volume

Fluid deficit should not exceed

Less than 2% body mass

Miscalculation of sweat loss

Underestimation

A potentially serious medical condition in which the plasma Sodium falls below 135 mmol/L, usually the result of fluid intake greatly exceeding sweat losses during prolonged exercise

Exercise Associated Hyponatremia (EAH)

Exercise Associated Hyponatremia (EAH) effects

Hyperhydration dilutes Extracellular Sodium which allows an Influx of of water in the Intracellular space which can lead to cells in the brain stem rupturing leading to coma or death. During exercise, blood flow to the kidneys is greatly decreased which does not clear existing fluid

Symptoms of Severe EAH

Coma and Seizures; Death

Mild Symptoms of EAH

Sweat Loss Volume Kilograms Equation

Initial Weight (kg) - Post-exercise weight (kg) + Fluid Consumption (kg) - Urine volume (kg)

EAH Symptoms

Weakness, Cramping, Vomiting, Disorientation and Confusion

Most popular methods to determine Pre-Exercise Hydration

Changes in Body Mass and Urinalysis

Body Mass in detection of Hydration Status

Record Morning Body Weight after voiding for a 3 day period and use a 1% decrease from a 3 day body-mass mass as a marker for Hypohydration

Aspects of Urinalysis to gauge real time hydration status

Osmolality, Color and Specific Gravity

Urine Color Chart

1-3 Hydrated, 4 - 8 Dehydrated

Measurement that represents a ratio of solutes in Urine compared to Distilled Water

Urine-Specific Gravity (USG) Manual Refractometer

Simple Hydration Advice

Encourage 500 mL of water before bed and another 500 mL 2 hours before exercise

Fluid strategies for endurance athletes

Place fluids along routes, place routes that pass water fountains, carry hydration packs, hand bottles, Sweat-loss assessment

Fluid and Electrolyte intake between two consecutive training sessions or competitions

Recovery Hydration

Key to Recovery Hydration

Replace Sweat-loss fluids and maximize the retention of these fluids before the next training session

ACSM Guidelines for Recovery Hydration

When less than 12 hours, Athletes should replace 150% of their sweat loss via beverage fluids

Supports Fluid Retention by decreasing Relative Urine Retention

Sodium, Protein and Carbohydrates

Five Steps for Developing a Hydration Strategy

1. Establish a Sweat-Loss Volume 2. Consume 500 mL before bed and 500 mL 1-2 hours before exercise if sweat-loss volume is expected to be Less than 3% 3. Prescribed Fluid intake if Above 3%; Provide opportunities for fluid intake Ad Libitum 4. Avoid exercise with extreme thirst of Dark Urine 5. Educate clients with Specific Gravity above 1.025 to consume 110 -120% Sweat Loss. Snacks

Signaling mechanism that triggers thirst from a significant loss of total body water from sweating

Baroreceptor

1.5 kg equals how many liters of sweat

1.5 L (Kg roughly equals Liters)

Greatest concentration of Intracellular Fluid

Potassium