Does Moderate Altitude Affect VO₂max in Acclimatized Mountain Guides?

Area of Science:

• Sports Medicine
• Altitude Physiology
• Exercise Science

Background:

• Altitude exposure typically reduces maximal oxygen uptake (VO2max), with effects often persisting even after acclimatization.
• Previous research indicates that highly trained athletes experience more pronounced VO2max reductions at altitude compared to non-athletes.
• The impact of moderate altitude on VO2max in well-acclimatized individuals, such as mountain guides, remains less understood.

Purpose of the Study:

• To investigate whether acute exposure to moderate altitude (2,000m) affects VO2max in acclimatized mountain guides.
• To determine if baseline fitness levels influence the preservation of VO2max at moderate altitude.
• To assess physiological responses, including heart rate and lactate levels, during submaximal exercise at moderate altitude.

Main Methods:

• 128 acclimatized male mountain guides performed two incremental cycle ergometer tests one week apart.
• Tests were conducted at low altitude (600m) and moderate altitude (2,000m).
• Measurements included oxygen uptake, heart rate, and blood lactate concentration.

Main Results:

• Lower baseline VO2max was associated with better VO2max preservation at 2,000m compared to higher baseline VO2max levels.
• Physiological responses (heart rate and blood lactate at 100W) at submaximal exercise intensity remained unchanged or slightly decreased at moderate altitude.
• Individuals with VO2max below the 80th percentile showed preserved VO2max, while those with higher fitness levels experienced potential negative effects.

Conclusions:

• Long-term acclimatization to moderate altitude can prevent VO2max decline at 2,000m, particularly in less fit individuals.
• Higher fitness levels may still lead to a negative impact on VO2max at moderate altitudes.
• Findings are relevant for professionals regularly working at moderate altitudes, including guides, military, and rescue personnel.