Physical Activity at Altitude

What does decrease in ambient oxygen lead to

The Decrease in ambient oxygen leads to arterial hypoxia

What happens at higher altitude elevations

decreased PaO2

decreased PiO2

decreased SaO2

Acclimatization

adaptations produced by changes in the natural environment, whether through a change in residence or climate

Altitude Acclimatization

adaptive response in physiology and metabolism that Improve tolerance to altitude hypoxia

Immediate altitude adjustment- Pulmonary and acid-base balance

Hyperventilation- increase rate + depth of breaths (chemoreceptors detect low O2 partial pressure)

Bodily fluids become more alkaline from reduced CO2 w hyperventilation

Long term altitude adjustment- Pulmonary and acid-base balance

Hyperventilation

Increased excretion of bicarbonate by kidneys

Immediate altitude adjustment- Cardiovascular Response

Increase in submaximal heartrate

Increase in submaximal cardiac output

Long term altitude adjustment- Cardiovascular Response (HR, CO, SV)

submax HR elevated

submax CO falls below sea level values

submax SV decreases

Max CO decreases

What is the rate of decline in VO2max per elevation increase

A progressive decline in VO2max occurs at a rate of 10% per 1000 meters

What do cardiovascular longterm responses to altitude mean for training

These changes contribute to the inability to increase performance at sea level after training at altitude

Long term altitude adjustment- Hematologic

Decreased Plasma Volume

Decreased PaO₂ is detected by hypoxia inducible factor (HIF), which stimulates increased secretion of erythropoietin. EPO stimulates:

Increase in red blood cell number

Increase in hematocrit

Increase in hemoglobin concentration

Long term altitude adjustment- Muscle changes (capillarization, mitochondrial density, myoglobin, aerobic enzymes, body/lean body mass)

Increased skeletal muscle capillarization
• Increased mitochondrial density
• Increased level of myoglobin
• Increased muscles’ aerobic enzymes
• Decreased body mass and lean body mass

What happens to sodium and water in urine at high altitude

Increased loss of sodium and water in urine- helps to concentrate the red blood cells, but risk for dehydration

Timing of altitude adaptation

It takes about 2 weeks to adapt to altitudes up to 2300 m; thereafter, each 610-m increase in altitude requires an additional week

Recommendation for athletes competing at altitudes

begin training immediately during acclimatization to minimize detraining effects

Athletes will demonstrate improvements in aerobic capacity and race times while training at altitude

How long for acclimatization adaptations to dissipate after returning to sea level

Acclimatization adaptations dissipate within 2 to 3 week after returning to sea level

What mappens to maximum oxygen uptake at high altitudes

maximum oxygen uptake decreases at high altitudes

What happens to the strenuousness of effort at altitude

The relative strenuousness of effort increases at altitude

What happens to arterial oxygen saturation at higher altitudes

arterial oxygen saturation decreases at higher altitudes

What happens as to VO2max a result of arterial desaturation in higher altitudes

Arterial Desaturation Results in Decreases in VO2max at Higher Altitudes

What happens to exercise ventilation volume at higher altitudes

exercise ventilation volume increases with altitude

What does acute exposure to altitude do to catecholamines

Acute Exposure to Altitude Demonstrates Progressive Increase in Catecholamines

What does increased sympathetic adrenal activity coincide with at high altitudes

Increased sympathetic-adrenal activity coincides with increased heart rate and blood pressure

Is the maximum effect of EPO stimulated increase in RBC, hematocrit, and hemoglobin immediate

no, the maximum effect of EPO stimulated increase in RBC, hematocrit, and hemoglobin takes time

What happens to race time when training at altitudes

training at altitude make training adaptations that increase time-trial performance at altitude, but decrements in race time occur compared to sea level

When does altitude not exert adverse effects on events

Altitude exerts no adverse effect on events lasting < 2 minutes

Why does altitude exert no adverse effect on events lasting < 2 minutes

in exercises less than two minutes, the body uses anaerobic metabolism

Does training at altitude improve performance at sea level

no training at altitude does not improve performance at sea level

Why live high train low

at altitude you get red blood cell benefits

at low altitude training you maintain the same exercise intensity

When is alitude sickness experienced

Altitude Sickness Is Generally Experienced at Altitudes of 3,000 Meters (~10,000 Feet) and above

Serious implications of altitude sickness

Pulmonary Edema

Brain Edema