Week 13

Question 1

physics of altitude - moderate

Answer 1

Moderate altitude – 1500m – 3000m- in relation to athletics, we are concerned with this altitude range

Question 2

physics of altitude high

Answer 2

greater than 3000 m. More than 40 million people live and work between 3000m and 5500m

Question 3

extreme altitude

Answer 3

over 5500m
* Mt Everest 8848 m

Question 4

P02 in dry ambient air at sea level

Answer 4

.209 X 760 mm Hg = 160 mm Hg

Question 5

P02 in dry ambient air at 3048m

Answer 5

209 X 510 mm Hg = 107 mm Hg.

Question 6

P02 in dry ambient air at summit of mount everest

Answer 6

8848m (29,028ft.) =.209X250mmHg=52mmHg.

Question 7

physics of altitude

Answer 7

Oxyhemoglobin dissociation curve - only a small change in percent saturation of hemoglobin is observed with decreasing PO2 until an altitude of about
3,000m.

Question 8

air temperature

Answer 8

Air temperature decreases linearly by 6.5C per 1000 meters of altitude or 2oC (3F) per 1000 ft.
– Burnaby mountain is about 1000 ft, we often get snow up here when there is rain in Vancouver.
* Air becomes increasingly dry with increasing altitude - water loss via respiratory tract is higher at high altitude.
* Solar radiation-UV radiation is more intense at high altitude- sunburn, snow blindness

Question 9

decreased density of air

Answer 9

decreased external air resistance and work
force of gravity is decreased with distance form the earths centre
higher altitudes have favourable effect on sprinting, jumping, and throwing events

Question 10

endurance athletes

Answer 10

Endurance Athletes may experience declines in VO2 max and effects on performance as low as 580 m.
* The critical alveolar PO2 at which an un-acclimatized person loses consciousness within a few minutes during acute exposure to hypoxia occurs at an altitude of 7000m.
– Airplanes cruising altitude 10000 m

Question 11

increasing altitude and cardiovascular system

Answer 11

VO2 =(HR X SV) X (CaO2 -CvO2)
* With increasing altitude, CaO2 (arterial) progressively decreases.
* To compensate, cardiac output initially increases during rest and sub-maximum exercise via increase in heart rate.
* Over the first week at altitude, cardiac output falls to or below sea level values for the same VO2 and there is a progressive increase in O2 extractionàmore efficient method of delivering O2.
* The most important long-term adaptation to altitude is an increase in the blood’s oxygen carrying capacity.

Question 12

hemoglobin concentration and increasing altitude

Answer 12

Hemoglobin concentration starts to increase during the first two days at altitude due to a decrease in plasma volume and an increase in RBC production by bone marrow.
* These hematological changes during acclimatization are dependent on an adequate iron intake

Question 13

pulmonary system

Answer 13

Decreased alveolar PO2 à decreased arterial PO2 à stimulation of aortic and carotid chemoreceptorsàincrease in ventilationà increase in PAO2 and PaO2
* Hyperventilation- decreased PACO2 and PaCO2- increase in blood pH (respiratory alkalosis)- plasma bicarbonate (HCO3-) levels decrease during first two days because the kidneys excrete excess HCO3- to compensate pH.

Question 14

pulmonary ssytem

Answer 14

After the acid-base balance is corrected, hyperventilation persists during acclimatization. Within a week at high altitude, a new level for VE is attained - 40 to 100% above sea level values.

Question 15

responses to exercise

Answer 15

VO2max. decreases 3-3.5% per 1000 ft. above 5000 ft.
* At 4300m VO2max. is
decreased approximately 30%.
* Submaximal effort for same workload is higher
Even after several months of acclimatization, VO2 max. and time to exhaustion still remains significantly below sea-level values.

Question 16

responses to exercise

Answer 16

The percentage reduction in VO2max. is equal in both trained and untrained individuals.
* Oxygen requirements for working muscle are the same at altitude as at sea level for the same submaximal workload.
* However, heart rate and minute ventilation will be greater, requiring slightly more O2 for the same work rate.

Question 17

decrease in v02 max during exercise is to

Answer 17

a) decreased oxygen content of arterial bloodà decreased a-vO2 difference in maximal exercise
b) after acclimatization - decrease in maximal cardiac output due to a decrease in maximum heart rate and stroke volume.
– The decrease in maximal stroke volume is most likely due to the reduction in venous return which is caused by the decreased blood volume - Starling mechanism

Question 18

blood and lactate levels during exercise

Answer 18

During heavy exercise, muscle and blood lactate levels are higher at altitude for any given workload for two reasons:
a) Since the VO2max. is reduced, any given workload now requires a higher percentage of the VO2max. to perform
b) There is a reduced blood buffering capacity due excretion of certain amount of bicarbonate via the kidneys.
* Higher level of perceived exertion for any workload.

Question 19

acclimatization limits

Answer 19

The highest permanent settlement is located at 17,000 ft. in the Andes
* It has generally been observed that acclimatization stops and physical condition & mental function begin to deteriorate at altitudes above 17,000 ft. (5200m).

Question 20

time required for acclimatization

Answer 20

the longer you stay at moderate or high altitude, the better you perform in aerobic events but it never reaches sea level values.
* The number of days needed to acclimatize depends on the altitude:
* The length of time required depends to a large extent on the individual. A few people will never acclimatize and will continue to suffer mountain sickness.

Question 21

high altitude exposure

Answer 21

Acclimatization to one altitude ensures only partial acclimatization to a higher altitude.
* High altitude exposure for periods longer than two weeks results in a significant reduction in both body fat and lean body mass due mostly to appetite depression.
* The benefits of acclimatization are probably lost within 2 or 3 weeks after returning to sea level.

Question 22

altitude training

Answer 22

In order to attain top performance at altitudes of 2000m (6500 ft) or higher, endurance athletes should acclimatize for 2-3 weeks before their major competition.
* Non-endurance athletes may arrive close to the time of competition.

Question 23

mountain sickness

Answer 23

During the first few days at altitude, athletes may experience acute mountain sickness, which may hinder their training.
* Since VO2max. is decreased at altitude, intensity of training must be decreased. However, this problem can be solved by living at altitude, but going down to lower altitudes for few hours per day to train – “sleep high, train low”.
* It is not necessary to train at a higher altitude than the actual place of competition.
* Some athletes consistently fail at altitude- complicates team selection.

Question 24

performance after return to sea level

Answer 24

It is clear that altitude acclimatization improves one’s capacity to work at altitude.
* Several studies have reported no increase in VO2max. or performance in running events at sea level after several weeks of living and training at altitudes ranging from 7500 to 13,000ft. compared with pre-altitude performance.
* There is no consistent scientific evidence to support training at altitude to improve sea level performance.

Question 25

adaptation to altitude which should increase V02 max on return to sea level

Answer 25

a) increased hemoglobin concentration b) local muscle adaptations - increased number of mitochondria, oxidative enzymes, etc. * Adaptations which hinder performance on return to sea level: a) decreased maximum stroke volume and maximum heart rate which persists for a few weeks b) increased VE at a given workload- extra oxygen goes to respiratory muscles during exercise c) decreased buffering capacity of blood for lactic acid d) specificity of training - while at altitude, unable to train at sea level pace. Thus, lower the absolute workload to perform aerobic exercise

Question 26

live high train low altitude training

Answer 26

Athletes who use this method of training live and/or sleep at moderate altitude (6500-9000 feet), while going to a lower elevation (less than 4000 feet), in reasonable proximity, for a few hours daily to train. The purpose of this procedure is to get the beneficial physiological altitude adaptations, while maintaining sea level training intensity. * This method of training results in better sea level performance than is obtained by living and training at altitude for a number of weeks and then returning to sea level to perform.

Question 27

altitude illness

Answer 27

Altitude illnesses are on a continuum and are not separate illnesses. * Most altitude illness is preventable. Proper management requires early diagnosis and prompt intervention. A. Prevention of Altitude Illnesses B. Acute Mountain Sickness C. High-Altitude Pulmonary Edema (HAPE) D. High-Altitude Cerebral Edema (HACE) E. Other Medical Problems at Altitude

Question 28

prevention of altitude illness- staged ascent

Answer 28

1. Staged ascent - Slow ascent to altitude while climbing * Once reaching 2500m (8000 ft.), do not ascend more than 300 – 600m (1000 * If possible, don’t fly or drive to high altitude. Start below 3000m (10,000 ft) and walk up. * Acclimatize to lower altitudes before going to high altitudes * “work high but sleep low” * If you begin to show symptoms of moderate altitude illness, don’t go higher until symptoms decrease. Don’t go up until symptoms go down! If symptoms increase, go down, down, down! * In the presence of extreme cold or heat, or severe exertion, it may be necessary to ascend even more slowly than the above recommendations.

Question 29

prevention of altitude illness- avoid alcohol

Answer 29

Avoid alcohol and other depressant drugs eg. barbituates, tranquilizers and sleeping pills decreases respiratory drive during sleep resulting in a worsening of the symptoms.

Question 30

prevention of altitude illness - high carb diet and exercise

Answer 30

a diet of at least 70% carbohydrates reduces symptoms of acute mountain sickness by about 30% and can be started one to two days prior to ascent. until acclimatized, it is best to exercise moderately, avoiding excessive breathlessness and fatigue.

Question 31

drug prophylaxis

Answer 31

there are several drugs that can lessen the symptoms of high altitude illness. However their use is not recommended as a routine measure. The drug of choice is acetazolamide (Diamox).

Question 32

acute mountain sickness

Answer 32

Can occur at altitudes>2000m(6500ft.) but more common>3000m * AMS occurs 12 - 36 hours after arriving at altitude and usually lasts 2 to 3 days. dependent on the elevation, the rate of ascent, and individual susceptibility. Many people will experience mild AMS during the acclimatization process. This condition is exacerbated by exercise during the first few hours of altitude exposure.

Question 33

AMS- symptoms and treatment

Answer 33

Symptoms - headache, fatigue, irritability, loss of appetite, nausea, vomiting, dizziness, insomnia, generalized weakness. The syndrome resembles an alcohol hangover. * Treatment – the only cure is either acclimatization or descent. Symptoms of mild AMS can be treated with pain medications for headache and Diamox. Moderate or severe AMS requires descent to lower altitudes.

Question 34

high altitude pulmonary edema

Answer 34

pulmonary edema - accumulation of fluid in the alveoli- decreased diffusing capacity for oxygen direct effect of hypoxia on systemic arterioles is vasodilation. * However, hypoxia in the lung causes vasoconstriction – Vasoconstrictionbetterredistributesbloodflowtobetterventilated areas of lung Physiology of HAPE * Vasoconstriction - increased pulmonary vascular resistance- right ventricle must generate a higher pressure- pulmonary hypertension- greatly elevated pulmonary capillary pressure - movement of fluid from the circulatory system to the pulmonary interstitial spaces and alveoli.

Question 35

HAPE symptoms

Answer 35

Symptoms - shortness of breath, severe fatigue, cough which sometimes produces a frothy and/or bloody sputum, tachycardia, severe headache, insomnia, chest tightness or congestion, blue or gray fingernails or lips, often a slight fever; may rapidly go on to unconsciousness and death. * The symptoms often begin at night when shortness of breath at rest may occur.Treatment - descend to lower altitude immediately with or without oxygen - diuretics are quite effective if and only if fluids are replaced as rapidly as they are excreted. - Diamox is effective for prevention and treatment - Dexamethasone will improve symptoms

Question 36

high altitude cerebral edema

Answer 36

Accumulation of excess fluid in the brain * Rare below 3600m (12,000 ft.) * Symptoms – loss of coordination, – Confusion – Hallucinations – severe headache – severe weakness and fatigue – coma * Treatment - same as for HAPE – Descend – Diuretics – Diamox – dexamethasone

Question 37

treatment of altitude illness

Answer 37

Treatment of altitude illness is based on four principles: (1) stop ascent in presence of symptoms (2) descend if no improvement or if condition worsens (3) descend immediately if HACE, HAPE, loss of coordination, or changes in consciousness are present (4) ill persons must not be left behind alone or sent down alone.