Ozone exposure limits cardiorespiratory function during maximal cycling exercise in endurance athletes

Area of Science:

• Environmental Health
• Exercise Physiology
• Pulmonary Medicine

Background:

• Ground-level ozone (O3) is a major air pollutant known to cause respiratory issues.
• The impact of ozone exposure on exercise performance, particularly during high physical exertion, remains incompletely understood.
• Exercise involves hyperpnea (increased breathing), which may alter the effects of inhaled pollutants.

Purpose of the Study:

• To investigate if peak real-world ozone levels diminish pulmonary function and exercise capacity in trained athletes.
• To determine if ozone exposure increases symptom development during exercise compared to clean air.
• To test the hypothesis that ozone exposure negatively impacts exercise performance.

Main Methods:

• A double-blinded, randomized crossover trial involving 20 aerobically trained participants.
• Participants underwent exercise trials under two conditions: exposure to 170 ppb ozone or room air (<10 ppb ozone).
• Exercise protocols included moderate-intensity warm-up, heavy-intensity exercise, and a time-to-exhaustion test.

Main Results:

• No significant differences in oxygen uptake or ventilation were observed during submaximal exercise between ozone and room air conditions.
• During maximal exercise (time-to-exhaustion test), participants exhibited significantly lower end-exercise oxygen uptake, minute ventilation, and tidal volume when exposed to ozone.
• A trend towards lower exercise duration was noted in the ozone condition, suggesting reduced exercise capability.

Conclusions:

• Exposure to peak real-world ozone levels significantly reduces oxygen uptake and alters ventilation patterns during maximal exercise in highly trained athletes.
• The observed decreases in oxygen uptake and changes in respiratory patterns during maximal exercise suggest a limitation in oxygen transport.
• The combined effects of ozone dose and exercise intensity likely influence the severity of physiological responses, highlighting the need for further research into mitigation strategies.