Chapter 24 - Physical Activity at Medium and High Altitude Flashcards
(126 cards)
1
Q
What are the effects of being at near sea-level altitude?
A
No Effects On:
- Well-being
- Performance
2
Q
What is considered near sea-level altitude?
A
- Below 500m
3
Q
What is considered low altitude?
A
- 500-2000m
4
Q
What are the effects of low altitude/
A
- No effect on well-being
- Performance may be diminished
5
Q
At what level of low altitude might athletes performance be diminished?
A
- above 1500m
6
Q
How might performance decrements seen in low-altitude be overcome?
A
- Acclimatization
7
Q
What level is moderate altitude?
A
- 2000m-3000m
8
Q
What effects are seen at moderate altitudes?
A
- Well-being effects on unacclimated individuals
- Decreased maximal aerobic capacity and performance
9
Q
Can optimal performance at moderate altitude be restored?
A
- may or may not be restored with acclimatization
10
Q
What level is considered high altitude?
A
- 3000-5500m
11
Q
What are the effects of high altitude?
A
- Adverse health effects in most individuals
- Significant performance decrements even with full acclimatization
12
Q
What does the physiologic challenges at high altitude come from?
A
- decreased ambient partial pressure of oxygen (Po2)
13
Q
What does the oxygen transport cascade refer to?
A
- Progressive changes in the environment’s O2 pressure and body areas
14
Q
What does the oxygen transport cascade represent?
A
- Oxygen cascade at different elevations
15
Q
What must air that we inspire be?
A
- Warmed and humidified
16
Q
What is the partial pressure of water at body temperature?
A
- 47mmHg
17
Q
What does alveolar Po2 determine by?
A
- The removal of O2 into the pulmonary capillary blood and the addition of O2 from ventilation
18
Q
What is the slight decrease in Po2 between alveolar air and arterial blood?
A
- 5mmHg
19
Q
What is the Po2 of 40mmHg in mixed-venous blood due to?
A
- Tissue oxygen use
20
Q
What are some possible well-being effects at 1500m?
A
- Lightheadedness
- Headaches
21
Q
What are some possible well-being effects at 3000m?
A
- Insomnia
- Nausea
- Vomitting
- Pulmonary Discomfort
22
Q
What are some possible well-being effects at 4000m?
A
- Dyspnea
- Anorexia
- GI disturbances
23
Q
What are some possible well-being effects at 6000m?
A
- Lethargy
- General Weakness
24
Q
What are some possible well-being effects at 8000m?
A
- Impending collapse
25
How much does air temperature decrease with ascent?
- About 1C per 150m
26
What is the average temperature near the summit of Mount Everest?
-40C
27
What poses a serious risk of cold-related disorders at altitude?
- Low temperature
- Low ambient water vapor pressure
- High winds
28
How does the extremely low partial pressure of water at high altitude lead to dehydration?
- Evaporation of moisture from skin surface due to the large gradient between skin and air
29
At what point would there be a significant change in hemoglobin percent saturation with O2?
- approx 3000m
30
What happens to hemoglobin oxygenation when you transition from moderate to higher altitudes?
- Dramatic decrease
- Negative affect on mild-intensity aerobic exercise
31
Define Acclimatization
- Refers to adaptations produced by changes in the natural environment, whether through a change in season or place of residence.
32
Define Acclimation
- Adaptations produced in a controlled laboratory environment
33
What does altitude acclimatization describe?
- adaptive responses in physiology and metabolism that improve tolerance to altitude hypoxia
34
What is the response to immediate exposure of elevations >2300m?
- Rapid physiologic adjustments to compensate for thinner air and the accompanying reduction in alveolar PO2
35
What are some important immediate adjustments made in response to elevations above 2300m?
Increase
- respiratory drive to produce hyperventilation
- Blood flow during rest and submaximal exercise
36
What does hyperventilation from reduced arterial Po2 reflect?
- Significant immediate response to native low-landers to altitude exposure
37
What does a hyperventilation response to high altitudes do?
- Hypoxic drive increases
38
When does an increase in hypoxic drive increase? How long does it remain elevated?
When
- First few weeks
How Long
- A year or longer during prolonged exposure
39
What happens to resting blood pressure in early stages of altitude adaptation?
- Increases
40
What happens to submaximal exercise heart rate and cardiac output in altitude?
- Rises to 50% above sea level values
41
What happens to stroke volume at submaximal exercise in altitude?
- Remains unchanged
42
What compensates for arterial desaturation at altitude?
- Increased submaximal exercise blood flow
43
What happens to the sympathoadrenal activity during rest and exercise with altitude?
- Progressively increases over time
44
What coincides with increased blood pressure and heart rate at altitude?
A steady rise in:
- Plasma levels
- Excretion rates of epinephrine
45
What does an increased sympathoadrenal activity in altitude contribute to?
Regulation of:
- Blood pressure
- Vascular resistance
- Substrate mixture during short- and long-term hypobaric exposure
46
Sketch the Catecholamine Response of Altitude?
- Check Notes
47
Sketch the Comparison of O2 Cost and Relative Strenuousness of submaximal exercise at sea level and altitude
- Check Notes
48
Sketch the comparison of cardiorespiratory and metabolic responses during exercise at Sea Level and Altitude
- Check Notes
49
What allows body water to evaporate as inspired air becomes warmed and moistened in respiratory passages?
- Ambient air in mountainous regions remains cool and dry
50
What leads to moderate dehydration and accompanying dryness of lips, mouth, and throat at high altitudes?
- Fluid loss
51
When does fluid loss become pronounced at high altitudes? Why?
When
- physically active people
Why
- large daily total sweat loss
- Exercise pulmonary ventilation
52
Sketch the response to altitude of sensory functions
- Check Notes
53
What are the immediate pulmonary acid-base responses to altitude?
- Hyperventilation
- Bodily Fluids become more alkaline due to reduction in carbon dioxide with hyperventilation
54
What are the longer-term pulmonary acid-base responses to altitude?
- Hyperventilation
- Excretion of base (HCO3-) via the kidneys and concomitant reduction in alkaline reserve
55
What are the immediate cardiovascular responses to altitude?
Increase
- submax HR
- submax Cardiac Output
Same or Slight Decrease
- Max Cardiac Output
- Stroke Volume
56
What are the longer-term cardiovascular responses to altitude?
- Submax HR elevated
- Submax Cardiac Output below sea-level
- Stroke Volume Decreases
- Max Cardiac Output decreases
57
What are the longer-term hematological responses to altitude?
Decreased
- Plasma Volume
Increased
- Hematocrit
- Hemoglobin Concentration
- Total # Red blood cells
58
What are the longer-term local responses to altitude?
Increased
- capillarization of skeletal muscle
- Red blood cell 2,3-DPG
- Mitochondria Density
- Aerobic Enzymes in Muscles
- Loss of body weight/lean body mass
59
how does the effect of hyperventilation at altitude to increase alveolar PO2 relate to the bodies CO2 level?
- Opposite Effect
60
What does carbon dioxide loss from fluids in the body create?
- Physiologic disequilibrium
61
How does the body manage the disequilibrium created by the carbon dioxide loss from fluids at altitude?
- Produces CO2 via the action of carbonic anhydrase
62
What does the high level of carbonic anhydrase activity do?
- decreases H+ in the blood
- Makes body fluids more alkaline
63
How does the body control ventilatory-induced alkalosis?
Very Slowly
- kidneys excrete base (HCO3-) through the renal tubules
64
What does the control of ventilatory-induced alkalosis by the kidneys through the renal tubules do?
Restores normal pH
65
What happens when the pH is restored by the kidneys following ventilatory-induced alkalosis?
- Increases the respiratory center's responsiveness to enable an even greater hyperventilation response
66
What does establishing acid-base equilibrium with acclimatization occur at the expense of?
- Loss in absolute alkaline reserves
67
What happens to blood lactate concentrations during submaximal exercise on immediate ascent to altitude compared to sea-level values?
- Increased
68
What is an explanation for the increases in blood lactate accumulation during submax exercise during immediate ascent to altitude?
- Increased reliance on anaerobic metabolism
69
What happens following several weeks of altitude exposure at the same submaximal and maximal intensity exercises?
- Large muscle groups produce lower blood lactate levels
70
What does lower blood lactate levels at the same submax or max intensity following several weeks of altitude exposure occur despite of?
- Lack of increase in VO2max or regional blood flow in active tissues
71
Where does research point to involving the lactate paradox?
- Reduced output of epinephrine (during exercise)
- Its controversial
72
What does epinephrine do for glucose?
- Mobilizes hormone
73
What reduces the capacity for lactate formation?
- Reduced glucose mobilization
74
What might reduced lactate formation during maximal exercise at high altitudes partly reflect?
- Reduced CNS drive
75
What does a reduced CNS drive do?
- Reduces capacity for all-out effort
76
What is the most important longer-term adjustment to altitude exposure?
- Increase in blood's oxygen-carrying capacity
77
What two factors account for the adaptation of increased blood oxygen-carrying capacity?
- Initial decrease in plasma volume
- Increase in erythrocytes and hemoglobin synthesis
78
What happens to the body fluid in the first several days of altitude exposure?
- Shifts from the intravascular space to the interstitial and intracellular space
79
What does the decrease in plasma volume that occurs within several hours of altitude exposure do?
- Increases red blood cell concentration
80
What happens after a week at 2300m regarding plasma volume?
- Declines about 8%
81
What happens after a week at 2300m regarding red blood cell concentration and hemoglobin?
Red Blood Cell Concentration
- Increases 4%
Hemoglobin
- Increases 10%
82
What does the rapid plasma volume reduction do compared to the arrival at altitude values?
- increases the oxygen content of arterial blood
83
Define Diuresis
- Increased urine output that accompanies the fluid shift from plasma during acclimatization
84
What does diuresis do?
- Maintains balance in the fluid compartments despite a lower total body water content
85
What does a reduced arterial Po2 at altitude stimulate?
- Increase in total number of red blood cells, or polycythemia
86
What initiates red blood cell formation?
- Erythropoietin
87
How quickly does the initiation of red blood cell formation from erythropoietin occur?
- within 15 hours after altitude ascent
88
Where does erythrocyte get produced?
- The marrow of the long bones
89
What happens to erythrocyte production during prolonged altitude stay?
- Remains elevated
90
What is seen in some healthy high-altitude natives?
- High red blood cell count compared to native lowlanders
91
What does the blood of a typical miner in the Andes contain?
- 38% more erythrocytes than lowlanders
92
What happens to well-acclimatized mountaineers' blood carry?
- More oxygen per deciliter than lowland residents
93
What is the result of increased hemoglobin concentration?
- Even with reduced hemoglobin oxygen saturation at altitude, the quantity of oxygen in arterial blood may approach or even equal sea-level values
94
What can chronic hypoxia do?
- Initiate remodeling of capillary diameter and length
95
How does chronic hypoxia's initiation of remodeling of capillary diameter and length?
- formation of new capillaries
96
What does the formation of new capillaries due to chronic hypoxia do?
- Increase oxygen conductance to neural tissues
97
What do human residents of sea level also increase during an altitude stay?
- Increase tissue capillarization
98
What reduces the oxygen diffusion distance between blood and tissues? What does it do?
What
- Prolific Microcirculation
Do
- Optimizes tissue oxygenation at altitude when arterial PO2 decreases
99
What do muscle biopsy specimens from humans living at altitude indicate?
- Myoglobin increases up to 16% after acclimatization
100
What does additional myoglobin do?
- augments oxygen "storage" in specific fibers
- Facilitates intracellular oxygen release and delivery at a low-tissue PO2
101
What does the increased concentration of red blood cell 2,3-Diphosphoglycerate (2,3-DPG) facilitate?
- Oxygen release from hemoglobin in long-term altitude exposure
102
Sketch the Oxygen-Hemoglobin Dissociation Curve
- Check Notes
103
What does prolonged high-altitude exposure do to lean body mass and body fat?
- Reduction
104
What does daily caloric intake from depressed appetite decrease by during the exposure period?
- 43%
105
By how much did reduced energy intake reduce body mass? What is this predominantly from?
How much
- 7.4kg
from
- muscle component of fat-free body mass
106
What does time required for acclimatization depend on?
- Elevation
107
Does acclimatization to one altitude ensure acclimatization to higher elevations?
- Only partial adjustments
108
How long does it take to adapt to altitude up to 2300m?
- approx 2 weeks
109
What is the acclimatization rate after the initial 2 weeks for 2300m?
- 610m every week
110
When do small declines in VO2max become noticeable?
- 589m
111
What is the rate of decrease in VO2max due to arterial desaturation?
- 7-9% per 1000m
- Altitudes up to 6300m
112
When does the rate of VO2max decrease drastically?
- above 6300m
113
What does VO2max average at 7000m?
- one half that at sea level
114
Why might there be small improvements in endurance during acclimatization, despite lack of concomitant increases in VO2max?
- Increase in minute ventilation
- Increase arterial oxygen saturation/cellular aerobic functions
- Blunted blood lactate responses
115
What happens to VO2max after several months of acclimatization despite relatively rapid increases in hemoglobin concentration?
- Remains below sea-level values
116
What offsets the hematologic benefits of acclimatization?
- Lower max HR
- Decreased Stroke Volume
117
What increases submaximal cardiac output at altitude?
- immediate response to physical activity
118
What happens to increases in submax cardiac output as acclimatization progresses?
- Diminishes
- Does not improve with prolonged exposure
119
What happens to progressive decreases in stroke volume during altitude?
- Stays reduced
120
What happens with lower cardiac output at high altitudes?
- Submax oxygen consumption remains stable through expanded a-vO2diff
121
When does maximum cardiac output decrease? what happens after?
- after 1 week above 3048m
- Remains lower throughout stay
122
What is the reduced blood flow in high altitude a combined effect of?
- Decreased plasma volume (reduced stroke volume)
- Increase in parasympathetic tone
123
What is the increase in parasympathetic tone at high altitude induced by?
- prolonged altitude exposure reduces maximum heart rate
124
When doesnt sea-level exercise performance improve after living at altitude?
- When VO2max serves as improvement criterion
125
What effects of high altitude acclimatization do not enhance sea-level performance?
- Residual muscle mass loss
- Reduced max HR and SV
- Reduced Max Q
126
Why do increases in the blood's oxygen-carrying capacity not necessarily increase sea-level performance?
- Reductions in Maximum Cardiac Output
