Hydration and Exercise Flashcards
What are the typical volumes of different fluids in the body for a 70kg individual? (armstrong 2007)
28 L Intercellular fluid
11 L interstitial fluid
3 L Plasma
What are the characteristics of intracellular dehydration?
- Fluid loss is hypo-osmotic to plasma
- Loss of water is greater than loss of osmolytes = increase in plasma osmolality
- An osmotic gradiant is created and water loss is shared between ICF and ECF
- Associated with sweat loss due to exercise-heat stress
What are the characteristics of extracellular dehydration?
- Fluid loss is iso-osmotic with plasma
- Loss of water and osmolytes occur in equal proportions = normal blood chemistry
- The osmotic gradient to pull fluid from the larger internal reservoir is absent
- Associated with fluid losses induced by diuretics, diarrhea and cold and altitude
What volume of fluid loss leads to 2% dehydration in a typical 70kg individual?
1.4L
What does AVP stand for and what’s another name for it?
Arginine Vasopressin; A.K.A Antidiuretic Hormone or ADH
What roles does AVP have in dehydration? (explain step by step)
- Cellular shrinkage due to dehydration
- Sensed by osmoreceptors in brain
- Increase neural firing
- AVP secreted by hypothalamous
- Concentrates urine by increasing water absorption
What are measures of both ICD and ECD?
Bioimpedence, BIVA, symptoms and BUN/Cr in the blood
What are the primary measures of ICD?
Blood plasma osmolality, Urine osmolality, and Urine specific gravity
What is the range of euhydrated blood plasma osmolality?
280-290 mOsmol/kg
What is euhydrated urine osmolality?
less than 700 mOsmol/kg
What is dehydrated urine osmolality?
more than 900 mOsmol/kg
What is the euhydrated Urine specific gravity
less than 1.020 g/mL
When is the best time to measure urine osmolality?
First morning void
Which of plasma and urine osmolality is quicker to respond to de/re-hydration?
plasma is quicker. urine has a delay
What is the relationship between stroke volume/HR and fluid loss? (montain and coyle 1992)
SV: Proportional negative relationship. As more fluid is lost, stroke volume decreases
HR: Proportional positive relationship
What is the relationship between RPE and dehydration?
Positive correlation
Why does increased requirement of skin blood flow increase cardiac strain?
Creates competition between central and peripheral circulation for limited blood volume
Why might you dehydrate similarly doing the same activity in the cold as in the hot?
Because you wear more clothes when it’s cold, creating a micro-climate around you, causing you to sweat similar amounts to when it’s hot out
What did Cheuvront and Kenefick 2014 find about the impact of dehydration on endurnace vs strength and power?
High evidence to see that dehydration affects endurance. Not much evidence show that even up to 7% dehydration affects power/strength.
What did Watson et al 2005 find about the impact of dehydration on sprints and vertical jumps?
No significant differences between euhydrated and dehydrated.
What did Ebert et al 2007 find about dehydration and time to exhaustion?
TTE impaired in dehydration trial compared to control
what is ‘cognition’?
All mental processes allowing us to perceive, think and remember but also to feel emotions and exert control over our environment
What are the two broad subcategories of cognition?
Cognitive functions
Mood state
What has been found in terms of the relationship between cognitive function and dehydration?
Some have found as dehydration increases, cognitive function decreases.
Others see no relationship
Evidence that suggests dehydration deceases mood state?
Shirreffs et al 2004
Massento et al 2014
