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An Introduction to Carbon Monoxide Levels for Athletes

June 18, 2026 · The Clime Team
An Introduction to Carbon Monoxide Levels for Athletes

Carbon monoxide (CO) is a colorless, odorless gas produced by the incomplete combustion of carbon-containing materials. For athletes, exposure to elevated CO levels can pose significant health risks, potentially affecting performance and overall well-being.

What Are the Risks of Carbon Monoxide Exposure for Athletes?

Inhalation of CO reduces the blood's oxygen-carrying capacity by binding to hemoglobin, forming carboxyhemoglobin (COHb). Even at low concentrations, this can impair oxygen delivery to tissues, leading to symptoms such as dizziness, fatigue, and decreased exercise tolerance. Studies have shown that COHb levels between 3% and 6% can decrease exercise performance in healthy individuals. (ncbi.nlm.nih.gov)

How Does Carbon Monoxide Affect Athletic Performance?

Acute CO exposure can lead to:

  • Reduced Exercise Duration: Elevated COHb levels can shorten the time an athlete can perform at maximum capacity.

  • Decreased Maximal Exercise Effort: Higher COHb concentrations may lower the intensity an athlete can sustain during exercise.

  • Increased Fatigue: Impaired oxygen delivery can lead to quicker onset of muscle fatigue.

These effects are particularly concerning for athletes with underlying cardiovascular conditions, as CO exposure can exacerbate issues like angina and arrhythmias. (ncbi.nlm.nih.gov)

What Are the Sources of Carbon Monoxide Exposure for Athletes?

Athletes may encounter CO in various environments:

  • Indoor Venues: Poor ventilation in arenas or gyms can lead to CO buildup, especially if combustion engines are used nearby.

  • Outdoor Environments: Urban areas with heavy traffic can have elevated CO levels, affecting outdoor training sessions.

  • Altitude Training: Some training methods involve CO inhalation to increase hemoglobin mass, but this practice carries significant health risks and is banned by organizations like the Union Cycliste Internationale (UCI). (cyclingnews.com)

How Can Athletes Protect Themselves from Carbon Monoxide Exposure?

To minimize CO risks, athletes should:

  • Ensure Proper Ventilation: Train in well-ventilated areas to prevent CO accumulation.

  • Monitor Air Quality: Be aware of environmental conditions, especially in urban settings.

  • Avoid Harmful Practices: Steer clear of training methods that involve CO inhalation.

By understanding and mitigating CO exposure, athletes can safeguard their health and maintain peak performance.

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