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Exercise Physiology > Lecture 13 > Flashcards

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 1st 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 pulmonary diffusion at acute altitude?

A

At rest, pulmonary diffusion does not limit gas exchange with blood but at altitude, alveolar PO2 is still = with capillary PO2 so it impacts gas exchange
- Hypoxemia directly reflects the ;low alveolar PO2

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16
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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17
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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18
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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19
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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20
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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21
Q

Lecture 13:

When exposed to acute altitude; why does SVmax decrease?

A

SVmax decreases due to decresaed PV

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22
Q

Lecture 13:

When exposed to acute altitude; why does HRmax decrease?

A

HRmax decreases due to decreased SNS responsiveness

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23
Q

Lecture 13:

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

A

Decreased VO2max

24
Q

Lecture 13:

What happens to Basal Metabolic Rate?

A

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

25
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

26
Q

Lecture 13:

What does the Mt. Everest study (1981) explain about VO2max and O2 requirements?

A

When climbing Mt. Everest VO2max decreased from 62 to 15m/kg/min therefore if sea level VO2max is less than 50ml/kg/min than climbing is not possible without supplemental oxygen

27
Q

Lecture 13:

What happens to anaerobic performance at altitude?

A

Anaerobic perfromance is unaffected (eg; 100m vs 400m sprint)
- ATP_PCr & anaerobic glycolytic sysmtems are unchanged
- minimal O2 requirements during anaerobic

28
Q

Lecture 13:

What does the thinner air with altitude allow for?

A

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

29
Q

Lecture 13:

What happens when you are acclimated & chronically exposed to altitude?

A

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

30
Q

Lecture 13:

What are some pulmonary adaptations when chronically exposed to altitude (long-time exposure)?

A

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)

31
Q

Lecture 13:

What are some blood adaptations that occur from chronic altitude exposure?

A

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

32
Q

Lecture 13:

What are some consequences of polycythemia?

A

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

33
Q

Lecture 13:

What is polycythemia?

A

A blood disorder that occurs from having too many red blood cells in the body

34
Q

Lecture 13:

What are some changes that occur in muscle function & structure due to chronic exposure to altitude?

A
  • muscle cross-sectional area decreases
  • capillary density increases (more capillaries)
  • muscle mass decreases (weight loss & protein wasting)
35
Q

Lecture 13:

What happens to muscle metabolic potential due to chronic altitude exposure?

A

Muscle metabolic potential decreases due to;
- decrease in mitochondrial function
- decrease in glycolytic enzymes
- decrease in oxidative capacity

36
Q

Lecture 13:

What happened to the study of runners following chronic exposure to altitude?

A

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

37
Q

Lecture 13:

What are 3 negative effects of altitude on optimizing training & performance?

A

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

38
Q

Lecture 13:

What are 2 training strategies for sea-level athletes who will sometimes compete at altitude?

A

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

39
Q

Lecture 13:

What is the best training combination for altitude?

A

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%

40
Q

Lecture 13:

What did the study of 5k run times show about living high and training low?

A

No improvement was seen when living high/training high or living low/training low BUT significant improvement seen when living high & training low

41
Q

Lecture 13:

What is Artificial Altitude Training?
- does it improve performance?

A

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

42
Q

Lecture 13:

Training high vs training low & altitude acclimation

A

Training high stimulates altitude acclimation but training low doesnt lose altitude acclimation
- training low permits maximal aerobic training

43
Q

Lecture 13:

What is the best approach for optimizing training & performance with altitude?

A

Natural lignin high with low training is best approach for elite athletes
- artificial approaches are possibly beneficial for on-elite exercisers

44
Q

Lecture 13:

What is Acute Altitude (Mountain) Sickness?
- when does it occur? Symptoms?

A

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

45
Q

Lecture 13:

What are some possible causes of Altitude Sickness?

A

1.) low ventilators response to altitude
2.) accumulation of CO2 (acidosis)

46
Q

Lecture 13:

What is the most common symptom of altitude sickness?

A

Headache (continuous & throbbing) - experiences most at above 3,600m
*typically worse in morning & after exercise

47
Q

Lecture 13:

What is Altitude Sickness Insomnia?

A

The interruption of sleep stages prevented by Cheyenne-Stokes breathing
- incidence of irregular breathing increases with altitude

48
Q

Lecture 13:

What are some preventions & treatments for altitude sickness?

A

1.) gradual ascent to altitude (pre exposure to improve performance)
2.) Acetazolamine (+ steroids)
3.) artificial oxygen & hyperbaric rescue bags

49
Q

Lecture 13:

What are the 2 life-threatening conditions caused by altitude?

A

1.) High-Altitude Pulmonary Edema (HAPE)
2.) High-Altitude Cerebral Edema (HACE)
*can develop from severe altitude sickness & must be treated immediately

50
Q

Lecture 13:

What are the causes of HAPE

A

Likely related to hypoxic pulmonary vasoconstriction & clots forming in pulmonary circulation

51
Q

Lecture 13:

What are the symptoms of HAPE

A

Shortness of breath
Cough
Tiredness/fatigue
Decreased blood O2 levels
Cyanosis
Confusion
Unconsciousness

52
Q

Lecture 13:

How is HAPE treated?

A

Supplemental oxygen & immediate descent to lower altitude

53
Q

Lecture 13:

What are the causes of HACE?

A

HACE is caused by complications of HAPE above 4,300m altitude
- endemic pressure buildup (from fluid buildup) in the intracranial space

54
Q

Lecture 13:

What are the symptoms of HACE?

A

Confusion
Lethargy
Ataxia
Unconsciousness
Death

55
Q

Lecture 13:

How is HACE treated?

A

Supplemental oxygen & hyperbaric bag along with immediate descent to lower altitude

Exercise Physiology (11 decks)

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