Lecture 5: Hydration

Question 1

What is euhydration?

Answer 1

refers to a normal state of body water, with deviations from this norm producing compensatory responses

Question 2

What is hyperhydration?

Answer 2

A sustained increase in body water, although often transient

Question 3

What is hypohydration?

Answer 3

refers to a sustained decrease in body water

Question 4

What is dehydration?

Answer 4

refers to the process of losing water, rather than a state of low body water

Question 5

What percent of an adult athletes body mass is water?

Answer 5

Roughly 60-70%

Question 6

How is body water controlled?

Answer 6

Through thirst and kidney regulation of urine output

Question 7

What is the daily variation of body water content?

Answer 7

less than 1% of body mass

Question 8

How is water lost in the body?

Answer 8

• Faecal
• Respiratory
• Urine
• Sweat

Question 9

What are water gains?

Answer 9

• Metabolic Water production
• Food
• Drink

Question 10

What are the three ways urine is measure pre-exercise?

Answer 10

Urine osmolality, urine specific gravity and urine colour

Question 11

What is urine osmolarity?

Answer 11

How concentrated your urine is

Question 12

What are the disadvantages of measuring urine osmolality?

Answer 12

Expensive, accuracy needs first void sample

Question 13

What urine osmolality shows that you are euhydrated?

Answer 13

<700 mOsmol/kg

Question 14

What is urine specific gravity?

Answer 14

Compares the density of urine with the density of water

Question 15

What urine specific gravity means you are euhydrated?

Answer 15

<1.020 mg/cm3

Question 16

What are the disadvantages of urine specific gravity?

Answer 16

Accuracy needs first void sample

Question 17

What are the advantages of urine specific gravity?

Answer 17

Relatively cheap and quick results

Question 18

How do you use urine colour as a measure?

Answer 18

Look at the colour and compare on a scale

Question 19

What urine colour shows you are euhydrated?

Answer 19

<3 on scale

Question 20

What are the advantages of measuring urine colour?

Answer 20

Very cheap and quick results, good education tool

Question 21

What are the disadvantages of measuring urine colour?

Answer 21

Accuracy needs first void sample, affected by other dietary components

Question 22

What is serum osmolarity?

Answer 22

how concentrated your blood is

Question 23

What serum osmolarity shows you are euhydrated?

Answer 23

~285 mOsmol/kg

Question 24

What are the advantages of serum osmolality?

Answer 24

Accuracy is the gold standard

Question 25

What are the disadvantages of serum osmolality?

Answer 25

Expensive

Question 26

Does starting exercise hypohydrated help performance?

Answer 26

There is an association, not remarkably strong but starting exercise well hydrated is very important

Question 27

What state of hydration should you start exercise in?

Answer 27

in a euhydrated state

Question 28

What are the guidelines for hydration prior to exercise?

Answer 28

Slowly drink 5-7ml/kg at least 4 hours prior to exercise If urine still dark drink further 3-5ml/kg 2 hours prior

Question 29

What assists with fluid retention?

Answer 29

Sodium

Question 30

What is important about beverages in the heat?

Answer 30

Beverage temperature, we want to reduce core temperature as core temperature causes fatigue

Question 31

What are the effects of dehydration on exercise?

Answer 31

- Decrease in skill performance - Decrease in mental performance - Opening of the blood brain barrier - Increased perception of effort

Question 32

How does dehydration impair performance?

Answer 32

- Increased body temperature - Increased RPE - Decreased mood

Question 33

How do we measure dehydration?

Answer 33

= (body mass loss/initial body mass) * 100

Question 34

How to measure sweat loss in L?

Answer 34

= Body mass loss (kg) + fluid intake (L)

Question 35

How to measure sweat loss in L/h ?

Answer 35

= [ Body mass loss (kg) + fluid intake (L) / time (mins) ] x 60

Question 36

What is elite athletes perception of fluid balance compared to their actual fluid balance?

Answer 36

They lost a lot more than they thought, they though they would maintain/gain - they actually lost weight

Question 37

How are hydration stratagies traditionally promoted?

Answer 37

centered on the recognition of individual sweat rates

Question 38

How much do athletes and adults underestimate their sweat losses by?

Answer 38

around 40-50%

Question 39

What are the effects of overhydration?

Answer 39

- Increase in body mass - Urination - Dilution of blood sodium - Hyponatremia?

Question 40

What is Hyponatremia?

Answer 40

occurs when the concentration of sodium in your blood is abnormally low

Question 41

What serum concentration indicates hyponatremia?

Answer 41

[Na] <135 mmol/L

Question 42

What are the symptoms of hyponatremia?

Answer 42

- Fatigue - Lethargy - Brain aneurisms - Death

Question 43

What is the issue with the symptoms of hyponatremia?

Answer 43

Symptoms are similar to dehydration, therefore a lot of people were treated with MORE water, making the situation even worse.

Question 44

What is the incidence of hyponatremia in endurance events?

Answer 44

10-40%

Question 45

What type of exercise is a risk factor for hyponatermia?

Answer 45

Longer than 4h, slower speeds (more chance to drink), extremely hot or humid enviornments

Question 46

What personal characteristics are risk factors for hyponatermia?

Answer 46

Females, low body weight (lower total body water to start with)

Question 47

What medication is a risk factor for hyponatremia?

Answer 47

Non-steroidal anti-inflammatories (generally for pain)

Question 48

What is the biggest risk factor for hyponatremia?

Answer 48

Excessive fluid intakes

Question 49

What cannot prevent the development of exercise-associated hyponatraemia?

Answer 49

The addition of sodium to drinks ingested

Question 50

What are the ACSM drink guidlines?

Answer 50

- Try to limit dehydration to <1-2% loss in body mass - Avoid gaining weight

Question 51

What is the major electrolyte lost in sweat?

Answer 51

Sodium (20-80mmol/L)

Question 52

What are sweat potassium concentrations?

Answer 52

approx. 2-8mmol/L

Question 53

How do you calculate salt losses?

Answer 53

Sweat sodium concentration (mmol/L) x sweat loss (L/h)

Question 54

How to convert sweat sodium (mmol) to milligrams?

Answer 54

x 22.99

Question 55

Why is sodium included in sports drinks?

Answer 55

- Improves palatability - Maintains extracellular volume - May attenuate the decline in blood sodium

Question 56

How does sodium affect thirst?

Answer 56

Sodium ingestion may promote fluid intake via increasing thirst and delay dehydration

Question 57

How does sodium affect gastric emptying/intestinal absorption?

Answer 57

Sodium is important for intestinal absorption - however the inclusion of sodium in a drink does not effect gastric emptying of intestinal absorption

Question 58

What are the guidelines for dehydration recovery?

Answer 58

Smaller regular volumes best

Question 59

What does rehydration within 6 hours require?

Answer 59

volumes greater than deficits induced i.e., 1.5 * BM losses

Question 60

What are the aims of recovery after exercise?

Answer 60

- Restore Muscle and liver glycogen levels to pre-ex. - Rehydrate to restore fluid and electrolyte balance * 1.5* BM loss - Repair, muscle repair & regeneration

Question 61

How much water do you need to drink to replace weight lost during exercise?

Answer 61

Need to replace 1.5 times body mass lost to become Euhydrated post exercise

Question 62

Why do you need to drink more than you lose after exercise?

Answer 62

due to obligatory water losses

Question 63

What is the ideal ingestion rate of water?

Answer 63

Very unclear - Ingesting a given volume over a longer period of time is likely to result in more efficient rehydration

Question 64

What is sodium the major ion of?

Answer 64

ECF

Question 65

Why is salty water better to drink after exercise?

Answer 65

some sodium remains in the vascular space = plasma osmolality and sodium concentrations do not decline as may occur if plain water is ingested

Question 66

How does CHO affect rehydration?

Answer 66

enhances fluid retention if the concentration of carbohydrate (6-10%) and volume of fluid (150% BM loss) ingested are sufficiently high

Question 67

How does protein affect rehydration?

Answer 67

related to a slowing of the overall rate of fluid uptake

Question 68

What concentration of salt in sports drinks was most liked by athletes?

Answer 68

18 and 30mmol/L