Hydration and Exercise

Question 1

What are the typical volumes of different fluids in the body for a 70kg individual? (armstrong 2007)

Answer 1

28 L Intercellular fluid
11 L interstitial fluid
3 L Plasma

Question 2

What are the characteristics of intracellular dehydration?

Answer 2

• 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

Question 3

What are the characteristics of extracellular dehydration?

Answer 3

• 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

Question 4

What volume of fluid loss leads to 2% dehydration in a typical 70kg individual?

Answer 4

1.4L

Question 5

What does AVP stand for and what’s another name for it?

Answer 5

Arginine Vasopressin; A.K.A Antidiuretic Hormone or ADH

Question 6

What roles does AVP have in dehydration? (explain step by step)

Answer 6

• Cellular shrinkage due to dehydration
• Sensed by osmoreceptors in brain
• Increase neural firing
• AVP secreted by hypothalamous
• Concentrates urine by increasing water absorption

Question 7

What are measures of both ICD and ECD?

Answer 7

Bioimpedence, BIVA, symptoms and BUN/Cr in the blood

Question 8

What are the primary measures of ICD?

Answer 8

Blood plasma osmolality, Urine osmolality, and Urine specific gravity

Question 9

What is the range of euhydrated blood plasma osmolality?

Answer 9

280-290 mOsmol/kg

Question 10

What is euhydrated urine osmolality?

Answer 10

less than 700 mOsmol/kg

Question 11

What is dehydrated urine osmolality?

Answer 11

more than 900 mOsmol/kg

Question 12

What is the euhydrated Urine specific gravity

Answer 12

less than 1.020 g/mL

Question 13

When is the best time to measure urine osmolality?

Answer 13

First morning void

Question 14

Which of plasma and urine osmolality is quicker to respond to de/re-hydration?

Answer 14

plasma is quicker. urine has a delay

Question 15

What is the relationship between stroke volume/HR and fluid loss? (montain and coyle 1992)

Answer 15

SV: Proportional negative relationship. As more fluid is lost, stroke volume decreases
HR: Proportional positive relationship

Question 16

What is the relationship between RPE and dehydration?

Answer 16

Positive correlation

Question 17

Why does increased requirement of skin blood flow increase cardiac strain?

Answer 17

Creates competition between central and peripheral circulation for limited blood volume

Question 18

Why might you dehydrate similarly doing the same activity in the cold as in the hot?

Answer 18

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

Question 19

What did Cheuvront and Kenefick 2014 find about the impact of dehydration on endurnace vs strength and power?

Answer 19

High evidence to see that dehydration affects endurance. Not much evidence show that even up to 7% dehydration affects power/strength.

Question 20

What did Watson et al 2005 find about the impact of dehydration on sprints and vertical jumps?

Answer 20

No significant differences between euhydrated and dehydrated.

Question 21

What did Ebert et al 2007 find about dehydration and time to exhaustion?

Answer 21

TTE impaired in dehydration trial compared to control

Question 22

what is ‘cognition’?

Answer 22

All mental processes allowing us to perceive, think and remember but also to feel emotions and exert control over our environment

Question 23

What are the two broad subcategories of cognition?

Answer 23

Cognitive functions

Mood state

Question 24

What has been found in terms of the relationship between cognitive function and dehydration?

Answer 24

Some have found as dehydration increases, cognitive function decreases.
Others see no relationship

Question 25

Evidence that suggests dehydration deceases mood state?

Answer 25

Shirreffs et al 2004

Massento et al 2014