Chapter 11: Hydration Flashcards
Intracellular Fluid (ICF)
The water contained within a cell’s membrane, makes up approximately 2/3 of total body water.
Extracellular Fluid (ECF)
The water found outside of the body’s cells - ECF is found between cells and transported throughout the body via arteries, veins, and capillaries.
Osmolality
Describes the concentration of solutes in a liquid – various compartments hold fluids but the primary regulator of hydration status is the osmolality of ECF, specifically plasma osmolality. Multiple sites in the body house osmoreceptors that detect shifts in osmolality and generate responses to return the body to fluid and sodium homeostasis.
Dipsogenic Signal
Physiological factors such as high osmolality or low blood pressure, which prompt sodium and water appetite.
Baroreceptors
Specialized nerves that can sense change in pressure in the heart or blood vessels.
Hypo-Osmotic
A solution with a lesser concentration of solute (i.e., fresh water compared to salt water).
Gastric Emptying Rate (GER)
The rate at which fluids and their contents pass through the stomach via the pyloric sphincter and into the small intestine – the faster and more complete the GER, the more quickly carbohydrates and electrolytes can be absorbed into the mesentery system, where they feed the liver first and then the rest of the body via the vascular system.
Convection
The movement or flow of air over an object.
Euhydration
A normal hydration status.
Ad Libitum
Translates to “as desired” and refers to eating or drinking as you are normally driven to (i.e., not purposely overeating or undereating).
Exercise Associated - Hyponatremia (EAH)
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.
Urine-Specific Gravity (USG)
A measurement that represents the ratio of solutes in the urine versus distilled water.
Recovery Hydration
Fluid and electrolyte intake between two consecutive training sessions or competitions.
What are the 3 primary Involuntary actions that change the levels of fluid and electrolytes in the body?
Food & Beverage Intake, Sweat loss during exercise, Urine loss during recovery
What is the most significant influence-to-thirst for water?
ECF Osmolality
What other factors, aside from hydration status, can contribute to heat illness? Check all that apply.
Heat, Humidity, Convection
What other factors, aside from hydration status, can contribute to heat illness?
Environmental conditions, Level of exertion, Training status, Body composition, Clothing choice
In most cases, calculating the average client’s sweat loss is not necessary. However, for those clients that require a level of coaching where it is required, which equation provided yields a client’s sweat loss volume kilograms?
Initial Weight (kg) – Post-exercise weight (kg) + fluid consumption during (kg) – Urine volume (kg)
Because the use of osmolality and specific gravity strategies when determining hydration strategies are often impractical, a urine chart is often used to educate clients on their hydration status. Why is it important to collect and analyze urine in a clear container versus the toilet?
The urine in the toilet is diluted from the toilet water and will portray a false color indication used to compare with the Urine Color Chart.
Which of the following symptoms may be indicative of exertional rhabdomyolysis?
Extremely-dark-colored urine
Which item most accurately describes the role of fluid intake in regards to assisting body-temperature regulation during exercise in the heat?
Fluid intake can blunt increases in temperature during severe dehydration, but it cannot prevent all cases of heat illness.
Which item most appropriately describes the use of urine-specific gravity?
It should be assessed multiple times before exercise to determine if clients with heavy sweat losses routinely fail to consume adequate fluid during recovery.
A client completes three weight-training sessions with a Personal Trainer per week but also completes three, 1-hour group indoor cycle per week (not on the same day). They ask their Nutrition Coach for hydration advice. Which of the following responses would be most appropriate?
“Your workout sessions are not long enough in duration to cause sweat losses that dictate a personal hydration plan. Keep fluids available during exercise, and drink based on thirst.”
A client weighs 50 kg and is training to complete a cool weather half-marathon in a time of about 2 h. The client’s sweat losses are expected to equal 2 liters (about 4% of body mass). Which fluid intake goal would be most appropriate?
Begin the race euhydrated and simply drink to thirst.
A client’s pre-exercise weight is 75.0 kg. Their post-exercise weight is 73.5 kg. They consumed 0.25 liters of fluid during training. What was the volume of their sweat loss?
1.75 liters
Which of the following has research shown is true regarding most individuals engaged in training that produces significant sweat losses?
They significantly underestimate their sweat losses.
Which of the following scenarios would create the most optimal conditions for decreasing body temperature increase during exercise if the temperature and humidity were equal under each training scenario?
Cycling for an hour outdoors at 20 miles/hour
A client’s pre-exercise weight is 80.0 kg. Their post-exercise weight is 78.0 kg. They consumed 1.0 liters of fluid during training. What was the volume of their sweat loss?
3.0 liters
When assessing a client’s sweat losses, a Nutrition Coach determines that their change in body mass is approximately 1.5 kg. How many liters of sweat does this equal?
1.5 liters
A client who trains for triathlons has asked how much fluid he should consume between his morning runs and afternoon bike rides. He has determined his sweat losses from his early morning runs average around 2 liters. Which range of fluid intake would be most appropriate?
2.5-3.0 liters
What signaling mechanism triggers thirst due to a significant loss in total body water from sweating?
Baroreceptor
A client has repeatedly exhibited a pre-exercise USG range between 1.028 and 1.032. How would a Nutrition Coach interpret this finding?
The client needs to increase their fluid intake between training bouts.
A client weighs 70 kg and is training to complete a marathon in a time of about 4 h. The client’s sweat losses are expected to equal around 4 liters (about 6% of body mass). Which fluid intake goal would be most appropriate?
Drink 2 liters of fluid during the race.
Urine-specific gravity is best assessed with which tool?
Refractometer
