Exercise at High Altitude: Training and Competing Above Sea Level

When you exercise at altitude, everything changes. The reduced oxygen availability affects performance, recovery, and even poses health risks if you're not prepared. Whether you're hiking a 14er, competing in a mountain race, or just visiting a ski resort, understanding altitude's effects helps you exercise safely and effectively.

Understanding Altitude

Altitude Classifications

• Low altitude: Sea level to 4,000 ft (1,200 m) — minimal effects
• Moderate altitude: 4,000-8,000 ft (1,200-2,400 m) — noticeable effects
• High altitude: 8,000-14,000 ft (2,400-4,300 m) — significant effects
• Very high altitude: 14,000-18,000 ft (4,300-5,500 m) — severe effects
• Extreme altitude: Above 18,000 ft (5,500 m) — dangerous without acclimatization

What Happens at Altitude

• Lower air pressure = fewer oxygen molecules per breath
• Same percentage of oxygen (21%), but less density
• Body must work harder to deliver oxygen to muscles
• Heart rate increases for any given effort
• Breathing rate increases

Effects on Exercise

• Decreased aerobic capacity (VO2 max drops ~3% per 1,000 ft above 4,000 ft)
• Higher heart rate at same workload
• Faster fatigue
• Longer recovery needed
• Perceived effort feels harder

Acute Altitude Exposure

What to Expect (First 24-72 Hours)

• Shortness of breath during exertion
• Increased heart rate
• Faster breathing
• Headache (common)
• Fatigue
• Difficulty sleeping
• Decreased appetite

Acute Mountain Sickness (AMS)

Symptoms (typically 6-12 hours after arrival):

• Headache (hallmark symptom)
• Nausea or vomiting
• Fatigue
• Dizziness
• Difficulty sleeping

Mild AMS: Rest, hydrate, ibuprofen for headache, don't ascend further Moderate/Severe AMS: Descend immediately, seek medical attention

High Altitude Pulmonary Edema (HAPE)

Serious condition—fluid in lungs:

• Extreme shortness of breath
• Cough (may produce frothy/pink sputum)
• Fatigue out of proportion to effort
• EMERGENCY: Descend immediately, seek medical care

High Altitude Cerebral Edema (HACE)

Serious condition—brain swelling:

• Confusion, altered behavior
• Ataxia (loss of coordination)
• Decreased consciousness
• EMERGENCY: Descend immediately, seek medical care

Acclimatization

What It Is

Your body adapts to altitude over days to weeks:

• Increased breathing rate
• More red blood cells (takes weeks)
• Changes in oxygen delivery to tissues
• Improved efficiency

Timeline

• Day 1-2: Most symptoms
• Day 3-5: Significant improvement
• Week 1-2: Well-acclimatized for moderate altitude
• Weeks 2-4: Better adaptation for high altitude

Acclimatization Strategies

"Climb high, sleep low":

• Ascend during day
• Sleep at lower elevation
• Limits altitude exposure during sleep (when most vulnerable)

Gradual ascent:

• Above 8,000 ft: Limit sleeping elevation gain to 1,000-1,500 ft/day
• Every 3,000 ft: Take an extra rest day
• Don't rush

Pre-acclimatization:

• Arrive early before events
• Spend time at intermediate altitudes
• Altitude tents or masks (controversial, may help some)

Who Acclimatizes Differently

• Genetics play a role
• Fitness level doesn't prevent AMS
• Previous altitude success doesn't guarantee future success
• Some people never acclimatize well

Exercise Guidelines at Altitude

First 48 Hours

• Very light activity only
• No strenuous exercise
• Easy walking is fine
• Allow body to adjust

Days 3-7

• Gradually increase activity
• Reduce intensity 20-30% from sea-level efforts
• Monitor heart rate (will be elevated)
• Listen to body signals

After Full Acclimatization

• Near-normal training, but still modified
• Expect reduced peak performance
• Recovery takes longer
• Stay hydrated

General Principles

Intensity:

• Reduce by 20-50% initially
• Use perceived effort, not pace
• Heart rate will be higher at same effort
• Gradual return to normal over days/weeks

Duration:

• Shorter sessions initially
• Build up as acclimatized
• More rest between hard efforts

Recovery:

• Takes longer at altitude
• More rest days
• Extra sleep
• Adequate nutrition

Hydration and Nutrition

Increased Needs

• Dry air = faster fluid loss through breathing
• May not feel as thirsty
• Fluid needs increase 1-2 liters/day

Hydration Strategy

• Drink frequently, even without thirst
• Urine should be pale yellow
• Avoid excess alcohol (worsens dehydration and AMS)
• Limit caffeine initially

Nutrition

• Carbohydrate needs may increase
• Appetite often decreases at altitude
• Eat regular meals even if not hungry
• Iron supports red blood cell production

Supplements

• Acetazolamide (Diamox): Prescription medication that speeds acclimatization
• Iron: Only if deficient (test first)
• Others (beet juice, etc.): Limited evidence at altitude

Activity-Specific Guidance

Hiking

• Start with shorter, easier trails
• Ascend slowly
• Take frequent breaks
• Turn around if AMS symptoms develop
• Carry extra water and food

Running

• Significantly slow pace (30-50% slower initially)
• Shorter runs
• Walk uphills as needed
• Monitor for unusual fatigue or symptoms
• Avoid speedwork first week

Skiing/Snowboarding

• Many resorts at 8,000-12,000 ft base
• Gondola goes even higher
• Take it easy first day
• Hydrate (cold + dry + altitude = dehydration)
• Recognize AMS symptoms

Climbing/Mountaineering

• Follows strict acclimatization protocols
• Professional guidance recommended
• Know emergency descent routes
• Carry appropriate gear and communication

Cycling

• Reduced power output
• Descents cool you quickly
• Maintain hydration
• Adjust expectations for climbs

Altitude Training for Performance

"Live High, Train Low"

Athletes may live at altitude and train at lower elevation:

• Benefits of altitude exposure
• Ability to maintain training intensity
• Increases red blood cells over time

Altitude Camps

• 2-4 weeks at moderate altitude (6,000-8,000 ft)
• May improve sea-level performance
• Effects last 2-4 weeks after returning

Altitude Tents/Masks

• Simulate altitude while sleeping
• Mixed evidence for effectiveness
• Some athletes report benefits
• Expensive and cumbersome

Not for Everyone

• Some people don't respond
• Can interfere with recovery
• Should be periodized in training
• Work with coach/sport scientist

Returning to Low Altitude

After Living/Training High

• Performance may be enhanced for 2-4 weeks
• Time peak events appropriately
• Readjust to lower altitude quickly

De-acclimatization

• Body returns to sea-level function
• May feel "supercharged" briefly
• Effects fade over weeks

Special Populations

Those with Respiratory Conditions

• COPD, asthma, etc.
• Consult doctor before altitude travel
• May need supplemental oxygen
• Lower altitude threshold for symptoms

Those with Cardiovascular Conditions

• Heart disease requires medical clearance
• Altitude stresses cardiovascular system
• May need modified approach or avoidance

Pregnant Women

• Generally recommended to avoid very high altitude
• Moderate altitude may be okay (discuss with doctor)
• Reduced oxygen reaches fetus

Older Adults

• Can acclimatize well but may take longer
• More conservative approach
• Monitor symptoms carefully

Sample Acclimatization Plan

Day 1 (Arrival at 8,500 ft/2,600 m)

• Light walking only (20-30 min)
• Hydrate aggressively
• Rest and acclimate
• Go to bed early

Day 2

• Easy hike (2-3 miles, minimal elevation gain)
• Or: 30-min easy jog
• Continue hydrating
• Monitor for AMS symptoms

Day 3

• Moderate hike or longer easy run
• 50% of normal training intensity
• Feeling should start improving

Day 4-5

• 60-70% of normal training
• Add some moderate intensity
• Extend duration if feeling good

Day 6-7

• 80%+ of normal training
• Include some harder efforts
• Near full acclimatization for moderate altitude

Week 2+

• Normal training, still slightly modified
• Full high-intensity work
• Continue extra hydration and recovery

Warning Signs at Altitude

Stop and Rest If:

• Headache that worsens with exertion
• Unusual shortness of breath
• Confusion or clumsiness
• Nausea or vomiting
• Persistent fatigue

Descend Immediately If:

• Severe headache not relieved by rest/medication
• Difficulty breathing at rest
• Loss of coordination
• Confusion
• Persistent vomiting

Call for Help If:

• Symptoms of HAPE or HACE
• Unable to descend safely
• Someone loses consciousness

Moving Forward

Altitude adds challenge to exercise, but with proper respect and preparation, it's manageable and even beneficial. The key principles:

• Ascend gradually — give your body time
• Reduce intensity initially — let physiology adapt
• Hydrate extra — dry air depletes fluids faster
• Recognize warning signs — AMS can escalate quickly
• Be flexible — adjust plans based on how you feel

The mountains aren't going anywhere. There's no prize for pushing through dangerous symptoms. A smart, gradual approach lets you enjoy altitude exercise safely—and come back for more.

Respect the thin air. Adapt. Enjoy the view.