Chapter 9- Water Flashcards
(159 cards)
1
Q
what is the body’s principal way of getting rid of excess heat ?
A
sweating
2
Q
who has more %plasma in their body fluid- infants, men, or women?
A
adult men and women > infants
3
Q
in general, describe the distribution of proteins, fat, and water in babies’ bodies vs adult bodies
A
in adults, the three are more equally proportioned, but in babies, most of the body is water
4
Q
in most people, water accounts for what % of body mass
A
50-60
5
Q
how much water by mass in lean body tissues vs fat ?
A
75% in muscle, etc
vs 5% in fat
6
Q
who has more %interstitial fluid in their body fluid- infants, men, or women?
A
infants > men> women
7
Q
who has more %intracellular fluid in their body fluid- infants, men, or women?
A
infants > men > women
8
Q
why do men have more water content ?
A
they have more lean body mass and less fat than women
9
Q
who has more %total fluid in their body infants, men, or women?
A
infants> men> women
10
Q
who has more %fat- infants, men, or women?
A
women > men> infants
11
Q
what are the two variables which determine the proportion of body fluids ?
A
age and gender
12
Q
what are the 5 functions of water
A
resistance to temperature change cooling chemical reactions pH balance body fluids
13
Q
what is the major avenue of water loss during rest ?
A
urination (60%)
14
Q
what are the 4 avenues of water loss ?
A
urination 60% at rest
breathing
defecation
sweating
15
Q
during exercise, how much % water loss is through sweat
A
up to 90%
16
Q
what percent of energy is lost as heat ? what does this signify?
A
80%, meaning the body is not efficient at producing energy and using it
17
Q
explain how 80% of energy is lost as heat
A
for every L O2, 1 cal energy is produced and 4 cal heat
18
Q
calculate the energy made and the rate of heat production for an athlete consuming 4 LO2/min
A
4 LO2/min means that he is making it into 4x4=16 kcal/min heat and 4 kcal/min energy.
16 kcal/min heat= 960 kcal/L heat so this is the rate of heat production, which is 80% of the total energy production.
20% total energy would be 240 kcal/hr, and that means 240x 4.186 kJ/hr = 1004 kJ/hr
19
Q
where does the heat go in the body?
A
small proportion to skin, most to body core with venous blood
20
Q
during high intensity cycling, what happens to heat flow?
A
temperature increase in quads is 1 degree celsius / min which is a lot
21
Q
when temperature in muscle is too high, what cools it down ?
A
has to be cooled down or else contractile proteins and enzymes will denature
thermoreceptors in hypothalamus increase sweating and blood flow to skin
22
Q
during exercise at a constant work rate, how does heat production increase ?
A
in a square wave (step) fashion.
23
Q
when does the rise in body temperature plateau ?
A
when heat loss from body = heat production
24
Q
what causes the increase in core temperature in exercise ? (3)
A
exercise intensity
humidity
ambient temperature
25
what is the effect of a warm up on body temperature ?
intense warmup will increase core temp much higher and cause more fatigue
26
what is the temperature normally, in exercise, and in central fatigue ? what does this mean
36-38 normal
38-40 exercise
39.5 central fatigue
doesnt take a big increase for central fatigue
27
what is environmental heat stress determined by ? (4)
ambient temp
relative humidity
wind velocity
solar radiation (reflected from ground and direct)
28
what are the three ways heat is lost from skin by physical transfer ?
evaporation of sweat, convection, and conduction
29
what happens if the environment is hotter than the skin ?
heat is gained by convection and conduction , and evaporation can't occur
30
what is conduction ?
transfer of heat from one to another by direct contact
31
what is convection ?
heat exchange between solid medium and one that moves (air/water)
32
evaporation of 1L water= ? kcal ?
573
33
if you increase the ambient temperature and/or humidity how will sweat loss, core temp, and HR change
increase
34
if you decrease humidity but have high ambient temp how will sweat loss, core temp, and HR change
still will increase
35
at the same % humidity, but different temp, how will sweat loss, core temp, and HR change
higher temp will increase the variables
36
skin blood flow is an example of conduction or convection ?
convection (between solid medium and something moving)
37
at any given intensity, in which state will body temp increase faster?
dehydrated, also will be an increase in HR
38
what are the two heat inputs which determine heat load ?
exercising muscle and environmental heat gain from radiation, conduction, and convection
39
what is radiation ?
heat exchange w emission from one and absorption from other
40
what two things sense the heat load ?
the core and the skin
41
which body part integrates the info about heat load ?
hypothalamus
42
what are some modifying non thermal inputs received by the hypothalamus that can regulate temp ? (5)
```
blood pressure
osmolarity
Na+/Ca2+ ratio
hormones (estrogen)
cytokines (IL-6)
```
43
what is IL-6's role in modifying temp ?
raises set point temp of hypothalamus, causing rise of core temp in fever
44
what neurotransmitters can mediate hypothalamic sensory input ?
dopamine, serotonin, NE, and ach
45
what are the 5 ways that aerobic exercise from 70-100%Vo2max improves thermoregulation ? (2 blood, 3 sweating)
```
blood volume
blood flow
increased sweat gland size
earlier onset of sweating
increased sweat rate at a given core temperature
```
46
what relationship does dehydration upset ?
decreases sensitivity between sweat rate and core temperature, which causes fatigue and hyperthermia
47
what sickness happen when you can't adapt to dehydration ?
heat illness and cramps
48
what is the main point of how aerobic exercise training prevents hyperthermia:
maintains body at constant temperature during exercise in heat
49
exercise performance is impaired when a person is dehydrated at what degree ?
loss 2% of BW or more
50
does dehydration also affect sprint athletes ?
yes
51
what is the relationship between exercise capacity and body weight loss ?
inverse / negative
| the more body weight loss by dehydration, the less exercise capacity
52
how does dehydration affect glycogen use ?
the more dehydrated, the more the rate of glycogen use increases
this is because dehydration increases catecholamine response
53
how does body water loss affect Vo2max in lab or in other conditions?
body water loss higher in non-lab condition and causes a higher decrease in VO2max
54
what are the 4 negative and 2 positive relationships dehydration has with negative performance ?
decreased: blood volume, blood flow, sweat rate, heat dissipation
increased: core temperature, rate of muscle glycogen use
55
in an experiment with same people heat acclimated and unacclimated, what was found concerning core temperature ?
heat acclimation lowered core temperature when they were euhydrated compared to non-acclimated
however, when they were dehydrated, similar increases in core temperature were seen in both acclimated and non
56
does hypohydration affect force generation ?
yes
57
how does dehydration affect gastric emptying ?
reduced GE rate of ingested gluids
58
when should fluid consumption begin ? why ? (2)
during the early stages of exercise in the heat to minimize dehydration and also to maximize the bioavailability of digested fluids.
59
what is the mechanism of heat illness? talk about what happens in the blood and heart, and then what is produced and what happens to the gut
skin blood vessels dilate
pooling of blood in skin with increased heat loss
decreased central blood volume
decreased cardiac filling and stroke volume
increased heart rate to maintain same cardiac output
decrease in splanchic and renal and skin blood flow. this will all increase the core temperature
THEN, blood vessels will constrict from SNS as BP falls, meaning that ROS (reactive oxygen species) and nitric oxide (NO) will be produced, with NO being a specifically strong dilator. ROS will cause peroxidation of lipid membranes.
this will make membranes leaky; in the gut, this means more toxins will be able to come in, leading to endotoxemia (blood poisoning), and more hypotension.
consequence: organ injury, fainting
60
how does HR change in heat illness ? why ?
it has to increase to maintain cardiac output since SV decreases
61
what does ROS do ?
peroxidation of lipid membranes
62
what does ROS stand for ?
reactive oxygen species
63
what is a fancy word for blood poisoning
endotoxemia
64
what are risk factors for heat illness ?
```
dehydration
hot humid climate
obesity
lack of acc or PA
previous history
no sleep
medications
sweat gland dysfunction
upper respiratory/GI illness
```
65
why is obesity a risk factor for heat illness ?
larger body mass
66
how does sleep become a risk factor for heat illness
no sleep lowers HR max
67
which 2 medications are risk factors for heat illness
antidepressants (SSRI) and diuretics
68
what are the 2 most important factors in preventing heat illness ?
monitoring hydration status and promoting appropriate drinking
69
what is hyponatremia ?
low concentration of Na+ in blood
70
which population is hyponatremia most prevalent in
endurance athletes
71
what is the theory behind hyperhydration ?
explands blood volume which decreases plasma osmolarity, therefore improving heat dissipation
72
which compound is added to water for supposedly more effective hyperhydration ?
glycerol (increases fluid retention)
73
what is the caveat of hyperhydration studies ?
compare dehydration with hyperhydration states, while they should compare hyperhydration with euhydration
74
what did one hyperhydration study show about how hyperhydration can improve performance ?
increase of blood volume 400-500 mL improves cycling
75
how does glycerol help water absorption ? is it effective
absorbed in small intestine
increases medullary concentration in kidney, meaning you need more water absorption
effectiveness unclear
76
why is it unclear that glycerol helps water absorption ?
because it's hard to control for with rate of ingestion, timing, concentration of glycerol, exercise intensity duration, etc
77
during exercise, how can dehydration be avoided ?
by matching fluid consumption with weight loss
78
why is it hard to appropriately hydrate during exercise ? (3)
sweat rates vary
thirst is not a good indicator
limited opportunity to drink in certain sports
79
does water intake during exercise have an effect on time to exchaustion ? performance ? in thermoneutral ? in hot ?
yes yes yes yes
80
do most athletes drink enough during exercise ?
no because they drink ad libitum
81
how does time to exhaustion change if you dont hydrate during vs water regularly ?
improved endurance
82
in general, what is hypotonic ?
when there is more Na+ inside the cell which attracts water inside cell meaning less in intracellular fluid
83
what is a hypotonic drink ?
more water proportionally than nutrients
84
what is an isotonic drink ?
same water proportionally than nutrients
85
what is a hypertonic drink ?
more nutrients proportionally than water
86
which type of drink will have a lower concentration of salt ?
hypotonic
87
classify these in terms of their ability to improve time to exhaustion : no drink, water, isotonic, hypotonic
time to exhaustion will be improved in iso and hypo>>water>>no drink
88
classify these in terms of their ability to improve time to complete the trial : large fluid + CHO, large fluid, small fluid and CHO, small fluid
less time is better
improved time in large fluid + CHO>> large fluid > small fluid and CHO>> small fluid
therefore adding carbs to water has a beneficial effect on performance
89
what are the 5 reasons that sodium and other electrolytes are added to sports drinks ?
```
increase palatability
maintain thirst, to promote drinking
prevent hyponatremia
increase rate of water uptake
increase fluid retention
```
90
what is the effect of too much added carb in a drink ?
concentrated hypertonic solution is bad, delays the restoration of plasma volume during exercise
91
at what exercise stage should you be most concerned with replacing electrolytes ?
post exercise
92
does fluid intake matter for very strenuous exercise under 30 min ?
no because gastric emptying inhibited at high work rates, and insignificant amount of fluid will be absorbed
93
describe change in plasma volume after intake of hypotonic or hypertonic drink
for both, drop in plasma volume in first 15 mini
then, hypotonic drink will positively change the plasma volume more
the hypertonic drink is more concentrated, delays gastric emptying and slows absorption
94
what is the major electrolyte of extracellular fluids ?
sodium
95
explain how type of fluid consumption before exercise may improve time to exhaustion
no drink: short time to exhaustion
15%CHO-E drink a bit better
%CHO-E drink yields the best performance
therefore, w comparable hydration status a more hypotonic drink is better
96
what is the normal plasma sodium concentration ?
140-144 mmol/L
97
what is the plasma sodium concentration in cases of symptomatic hyponatremia ?
<130 mmol/L
98
what is the plasma sodium concentration in cases of hyponatremia with risk of seizure, coma, death?
<120 mmol/L
99
in what population is hyponatremia most common ? (3)
people who don't sweat a lot but drink large amounts of water or hypotonic fluids
women (sweat less)
people with cystic fibrosis genes (more prone to salt depletion)
100
as of <130 mmol/L sodium in plasma, what are some symptoms of hyponatremia ?
mental confusion, fainting, swelling of brain, edema
101
which hyponatremia symptoms are similar to dehydration ?
mental confusion, weakness, fainting
102
how often should one urinate w optimal hydration ?
1-2 hours
103
what kinds of foods and drinks should one abstain from to hydrate better ? (3)
caffeine, alcohol, and protein
104
what is the role of hydration before exercise ?
optimal sport performance with adequate hydration and fuel
105
what is the role of hydration during exercise ? (3)
MAINTAIN plasma volume, electrolyte balance, hydration
106
what are the two roles of hydration after exercise ?
replace water, electrolytes, and carbs lost
| restore body to euhydration
107
how much fluid should be consumed 2 hrs before exercise in mL or 6-8 mL/kg BW or oz?
500 mL or 6-8 mL/kg BW or 17 oz
108
how much fluid should be consumed 15 min before exercise in mL?
500
109
when should you start drinking fluids in preparation for exercise ?
24 hours prior
110
which vitamins add a yellowish hue to urine ?
B
111
what is the best indicator of hydration status ?
urine osmolality
112
what are three excellent choices for fluids before exercise ?
water, juice, milk
113
what are 5 things positively correlated with magnitude of water and electrolyte loss
```
body size
exercise intensity
ambient temperature
humidity
clothing
```
114
what is one thing negatively correlated w magnitude of water and electrolyte loss
acclimation
115
what is the rate of how much water and electrolyte do you lose in slow pace, low intensity effort in low to moderate temperature ?
<500 mL/hr
116
what is the rate of how much water and electrolyte do you lose in hot and humid environment ?
2000-3000 mL/hr
117
what is the formula for sweat rate ?
weight loss x fluids consumed during exercise / time of exercise (hr)
118
what are the units of sweat rate
L/hr
119
how much sodium is lost in sweat ?
1g sodium = 50 mmol sodium
| 20-80 mmol/L = 400-600 mg/L
120
how much potassium is lost in sweat ?
1g potassium = 20 mmol potassium
| 4-8 mmol= 80-150 mg/L
121
how much calcium is lost in sweat ?
small amounts
122
at what level should athletes maintain their hydration during exercise according to the consensus ?
less than 2% reduction in body weight
123
most athletes will achieve the consensus hydration recommendations by doing what ?
200-300 mL every 10-20 min during exercise
124
what is recommended that an athlete do to know how much to drink during exercise ?
sweat trials in different environments
125
how does volume of fluid digested affect fluid consumption and absorption during exercise ?
increased volume facilitates euhydration by stimulating gastric emptying: most athletes do not drink enough
126
how does the amount of carb in drink affect fluid consumption and absorption during exercise ? what are the recommendations ?
increasing carb amount prevents GI upset and helps maintain energy and power.
recommended 1g CHO/min (the same as 1L of an energy drink)
127
how does carb concentration affect fluid consumption and absorption during exercise ? what happens if it increases ?
recommended 6-8% carb solution
| more than 8%: decreases gastric emptying and intestinal absorption rates, causing GI disturbance
128
how can you determine CHO concentration in a drink ?
g CHO/240 mL x 100
129
how does type of carb in drink affect fluid consumption and absorption during exercise ?
recommended glucose and sucrose and glucose polymers
absorption maximized when you mix carbs
fructose not recommended
130
why is fructose not a good carb to include in sports drink ?
increases GI distress, but still some in sports drink for palatability
131
how does taste affect fluid consumption and absorption during exercise ?
flavored beverages increase fluid intake
132
how does exercise intensity affect fluid consumption and absorption during exercise ?
sports drinks are the recommended beverage for high intensity exercise, with CHO <7%
133
how do environmental conditions affect fluid consumption and absorption during exercise ?
high heat and humidity increases fluid needs, and you need CHO <7%
134
in which two cases are drinks with CHO <7% recommended ?
high intensity and high heat/humidity
135
how does altitude affect fluid consumption and absorption during exercise ?
increases fluid needs
136
how does colder temperature affect fluid consumption and absorption during exercise ?
colder air= drier air, water loss from humidification of passages, need more fluid
137
what are the two main electrolytes lost in sweat
Na and Cl
138
what are the Na+ intake recommendations for exercise >1hr
500-700 mg/ L water
139
is Na+ and Cl replacement physiologically necessary in exercise under 4 hours
no need but recommended
140
is Na+ and Cl replacement physiologically necessary in exercise over 4 hours
yes
141
what should one do in the first few days of heat acclimatization ?
may necessitate a temporary increase in sodium intake (maybe as high as 4-10g)
142
what are the 4 cases in which Na+ and Cl consumption during exercise is essential ?
exercise sessions > 4hrs
first acclimatization stages
ppl restricting sodium intake
ppl with not a well balanced meal before working out
143
what is the NATA recommendation for the 4 cases in which Na+ and Cl consumption during exercise is essential ?
add 0.3-0.7 mg sodium per L of fluid replacement, or even use salt tablets
144
what is the ideal temperature for a beverage
10-15 degrees
145
what is the protein recommendation for drinks ?
none
146
what is the ideal osmolality of a drink ?
hypotonic to plasma (290 mOsmol/L)
147
which 3 artificial sweeteners should be avoided ?
aspartame, saccharin, acesulfame potassium
148
which 3 drinks should be avoided bc they are stimulants ?
guarana, kola nut, caffeine
149
is the list of ingredients in order of weight or volume
weight
150
what are the 3 electrolytes we should have in beverages
Na, Cl, K
151
avoid products w a concentration of vitamins or minerals that___
have 10-20% DV in one serving.. this can cause GI distress. esp reconsider if 200% DV
152
what are 3 reasons you should avoid carbonated beverages when working out
full/bloated feeling
false sense of fullness
decrease fluid consumption
153
how much time does it take for ingested fluids to reach bloodstream? what does this mean ?
10-20 min so start drinking early
154
after how much time do you switch to sport drinks instead of water
60-90 min
155
what is the current recommendation for fluid after exercise
>150% weight loss within 6 hrs post exercise
156
what fluids should be had after exercise ?
a meal and water
| beverages like milk, soups, etc
157
what is the ideal beverage for post exercise replenishment containing (3)
carbs (restore muscle glycogen, increase intestinal absorption)
sodium (enhance fluid retention, restore electrolyte balance)
water
158
what is the recommendation for Na consumption post exercise
300-700 mg sodium/L of fluid lost in sweat
159
how fast should we rehydrate after exercise ?
ASAP (2 hrs after)
