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Lecture 13 Flashcards

1
Q

Lecture 13:

What is the barometric pressure at sea level?

A

Pb ~760mmHg @ sea level

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2
Q

Lecture 13:

What is the Partial Pressure of Oxygen (PO2)?

A

The portion of barometric pressure exerted by oxygen
- PO2 = 0.2093 —> 0.2093 x Pb = ~ 159mmHg @ sea level
- PO2 is reduced at altitude & limits performance

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3
Q

Lecture 13:

What is Hypobaria?

A

Reduced barometric pressure at altitude
- results from the decreased Pb = hypoxia & hypomexia

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4
Q

Lecture 13:

What is Low Altitude & how does it affect performance?

A

Low altitude = 500-2,000m
- does not effect well-being but may decrease performance
*performance can be restored by acclimation

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5
Q

Lecture 13:

What is Moderate Altitude & how does it affect performance?

A

Moderate Altitude = 2,000-3,000m
- affects well-being in unacclimated people
- performance & aerobic capacity decreased
*may or may not be restored by acclimation

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6
Q

Lecture 13:

What is High Altitude & how does it affect performance?

A

High Altitude = 3,000-5,500m
- acute mountain sickness occurs & performance decreases
*performance not restored by acclimation

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7
Q

Lecture 13:

What is Extreme High Altitude & how does it affect performance?

A

Extreme high altitude = greater than 5,500m
- has severe hypoxic effects
*highest settlements at 5,200-5,800m

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8
Q

Lecture 13:

What is air temperature like at altitude?

A

Temperature decreases 1deg C per 150m ascent
- contributes to risks of cold-related disorders

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9
Q

Lecture 13:

How does humidity change at altitude?

A

Cold air holds very little water & air at altitude is very cold meaning very dry air
- this dry air causes quick dehydration through skin & lungs

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10
Q

Lecture 13:

What is solar radiation like at altitude?

A

Solar radiation increases at high altitude due to snow reflecting & amplifying the radiation & low water vapour being unable to absorb the rays
- UV rays have less area to travel though

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11
Q

Lecture 13:

What happens to pulmonary ventilation when exposed to acute altitude?

A

Pulmonary ventilation increases immediately (at rest &submaximal exercise but not maximal)
- decreased PO2 stimulates chemoreceptors in aortic arch
- tidal volume increases for several hours or even days

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12
Q

Lecture 13:

How does ventilation change during acute altitude?

A

Ventilation increases & can cause hyperventilation
- alveolar PCo2 decreases and CO2 gradient increases

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13
Q

Lecture 13:

What is Respiratory Alkalosis?

A

High blood pH levels that cause the oxyhemoglobin curve to shift left
- prevents further hypoxia-driven hyperventilation

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14
Q

Lecture 13:

How do the kidneys adjust in acute altitude?
- how did they help with respiratory alkalosis?

A

Kidneys work to excrete more bicarbonate to minimize blood buffering capacity & can reverse alkalosis by returning blood pH to normal

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15
Q

Lecture 13:

What happens to oxygen transport in acute altitude?

A

The decrease in alveolar PO2 causes a decrease in hemoglobin O2 saturation
- oxyhemoglobin dissociation curve shifts left & shape/shift of curve minimizes desaturation

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16
Q

Lecture 13:

What happens to gas exchange at the muscles when in acute altitude?

A

Gas exchange at muscles decreases
- decreased PO2 gradient at muscle
- 60mmHg gradient at sea level, 15mmHg gradient @ 4,300m altitude, & 10mmHg at 5,800m altitude
- because gradient is drastically decreased, O2 diffusion into muscle is significantly reduced

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17
Q

Lecture 13:

What are some short term responses to acute altitude exposure?

A
  • Plasma volume decreases within a few hours (loss of up to 25%)
  • respiratory water loss and increase in urine production
  • short term increase in hematocrit & O2 density
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18
Q

Lecture 13:

What happens to red blood cells when exposed to acute altitude?

A

Red blood cell count increases after weeks/months
- increase in red blood cell production in bone marrow & long term increase in hematocrit

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19
Q

Lecture 13:

When exposed to acute altitude; what does decreased cardiac output result in?

A

Decreased cardiac output leads to decreased SVmax & decreased HRmax

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20
Q

Lecture 13:

When exposed to acute altitude; why does SVmax decrease?

A

SVmax decreases due to decresaed PV

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21
Q

Lecture 13:

When exposed to acute altitude; why does HRmax decrease?

A

HRmax decreases due to decreased SNS responsiveness

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22
Q

Lecture 13:

When exposed to acute altitude; what does decreased cardiac output and decreased PO2 gradient result in?

A

Decreased VO2max

23
Q

Lecture 13:

What happens to Basal Metabolic Rate?

A

BMR increases as thyroxine & catecholamine secretion increases and food intake increases to maintain weight

24
Q

Lecture 13:

Why do you dehydrate quicker and lose appetite at altitude?

A

Faster to dehydration ad water is lost through skin & kidneys/urine and exacerbated by sweating (need 3-5L fluid per day)
- appetite declines and metabolism increases
- iron increase required to support the increase in hematocrit

25
Lecture 13: What happens to anaerobic performance at altitude?
Anaerobic perfromance is unaffected (eg; 100m vs 400m sprint) - ATP_PCr & anaerobic glycolytic sysmtems are unchanged - minimal O2 requirements during anaerobic
26
Lecture 13: What does the thinner air with altitude allow for?
Thinner air means less resistance thus improved swim & run times (up to 800m as anaerobic & do not require O2) - improved jump distances & varied effects on throwing events
27
Lecture 13: What happens when you are acclimated & chronically exposed to altitude?
Performance is improved but may never match that at sea level - pulmonary, cardiovascular, & skeletal muscle changes occur - 3 weeks are required at moderate altitude to experience these changes but are lost after 1month back a t sea level *1 extra week per every additional 600m
28
Lecture 13: What are some pulmonary adaptations when chronically exposed to altitude (long-time exposure)?
1.) increased ventilation @ rest & submaximal exercise 2.) resting ventilation rate is 40% higher than that at sea level (over 3-4days) 3.) submaximal rate is 50% higher 9longer time frame to reach this)
29
Lecture 13: What are some blood adaptations that occur from chronic altitude exposure?
1.) EPO release increases for 2-3 days 2.) polycythemia stimulated (increase in red blood cell count) 3.) elevated red blood cell count for 3 or more months
30
Lecture 13: What are some consequences of polycythemia?
Hematocrit rises from 45% at sea level to 60% at 4,500m altitude - hemoglobin increases proportionally to elevation - oxyhemoglobin curve may or may not shift
31
Lecture 13: What is polycythemia?
A blood disorder that occurs from having too many red blood cells in the body
32
Lecture 13: What are some changes that occur in muscle function & structure due to chronic exposure to altitude?
- muscle cross-sectional area decreases - capillary density increases (more capillaries) - muscle mass decreases (weight loss & protein wasting)
33
Lecture 13: What happens to muscle metabolic potential due to chronic altitude exposure?
Muscle metabolic potential decreases due to; - decrease in mitochondrial function - decrease in glycolytic enzymes - decrease in oxidative capacity
34
Lecture 13: What happened to the study of runners following chronic exposure to altitude?
Runners showed no major cardiovascular adaptations - 2 months of altitude resulted in more tolerance to hypoxia but no changes in aerobic capacity *possibly because… reduced atmospheric PO2 inhibited training intensity @ high altitude
35
Lecture 13: What are 3 negative effects of altitude on optimizing training & performance?
1.) hypoxia @ altitude prevents high-intensity aerobic training 2.) living & training leads to dehydration, low blood volume, & low muscle mass 3.) altitude training for sea-level performance has not been validated
36
Lecture 13: What are 2 training strategies for sea-level athletes who will sometimes compete at altitude?
1.) Compete ASAP after arriving at altitude - no benefits from acclimation & too soon for adverse effects of altitude 2.) Train high for 2 weeks before competing - past worst adverse effects of altitude & aerobic training at altitude is not as effective
37
Lecture 13: What is the best training combination for altitude?
Living high, training low allows for the best of both worlds as it allows passive acclimation to altitude & training intensity not compromised by low PO2 - aerobic performance improves 1.1% & VO2max improves 3.2%
38
Lecture 13: What is Artificial Altitude Training? - does it improve performance?
Used to try and gain benefits of hypoxia at sea level by breathing hypoxic air 1-2 hours per day & training normally - found no improvement
39
Lecture 13: Training high vs training low & altitude acclimation
Training high stimulates altitude acclimation but training low doesnt lose altitude acclimation - training low permits maximal aerobic training
40
Lecture 13: What is the best approach for optimizing training & performance with altitude?
Natural lignin high with low training is best approach for elite athletes - artificial approaches are possibly beneficial for on-elite exercisers
41
Lecture 13: What is Acute Altitude (Mountain) Sickness? - when does it occur? Symptoms?
Onset 6-48hrs after arrival & most severe days 2-3 - Symptoms; headache, nausea/vomitting, dyspnea, insomnia - possible to develop into more lethal conditions - increases with altitude, rate of ascent, & susceptibility *higher incidence in women than men
42
Lecture 13: What are some possible causes of Altitude Sickness?
1.) low ventilators response to altitude 2.) accumulation of CO2 (acidosis)
43
Lecture 13: What is the most common symptom of altitude sickness?
Headache (continuous & throbbing) - experiences most at above 3,600m *typically worse in morning & after exercise
44
Lecture 13: What is Altitude Sickness Insomnia?
The interruption of sleep stages prevented by Cheyenne-Stokes breathing - incidence of irregular breathing increases with altitude
45
Lecture 13: What are some preventions & treatments for altitude sickness?
1.) gradual ascent to altitude (pre exposure to improve performance) 2.) Acetazolamine (+ steroids) 3.) artificial oxygen & hyperbaric rescue bags
46
Lecture 13: What are the 2 life-threatening conditions caused by altitude?
1.) High-Altitude Pulmonary Edema (HAPE) 2.) High-Altitude Cerebral Edema (HACE) *can develop from severe altitude sickness & must be treated immediately
47
Lecture 13: What are the causes of HAPE
Likely related to hypoxic pulmonary vasoconstriction & clots forming in pulmonary circulation
48
Lecture 13: What are the symptoms of HAPE
Shortness of breath Cough Tiredness/fatigue Decreased blood O2 levels Cyanosis Confusion Unconsciousness
49
Lecture 13: How is HAPE treated?
Supplemental oxygen & immediate descent to lower altitude
50
Lecture 13: What are the causes of HACE?
HACE is caused by complications of HAPE above 4,300m altitude - endemic pressure buildup (from fluid buildup) in the intracranial space
51
Lecture 13: What are the symptoms of HACE?
Confusion Lethargy Ataxia Unconsciousness Death
52
Lecture 13: How is HACE treated?
Supplemental oxygen & hyperbaric bag along with immediate descent to lower altitude
53
Lecture 13: What is Hypoxia?
Lack of oxygen to the tissues - prevents from functioning properly
54
Lecture 13: What is Hypoxemia?
Low oxygen levels in your blood (arterial)

Exercise Physiology (12 decks)

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