Performance-boosting poison, Cycling’s lactic acid myth

Performance-boosting poison Elite road cyclists are becoming chemistry experts. Lightweighting their equipment with sophisticated materials such as carbon nanofibers has helped ease these athletes over many hills. They’ve recently been leaning into manipulating their biochemistry—and not without controversy. Professional cyclists’ latest wheeze is to dose their lungs with the odorless but poisonous gas carbon monoxide using a device known as a carbon monoxide rebreather. Its use requires the person to inhale a small, precise amount of CO. The approach lets team doctors monitor a cyclist’s level of hemoglobin, the red blood protein responsible for delivering oxygen to tissue. CO binds to hemoglobin more effectively than oxygen and thus prevents oxygen from reaching tissues, muscles, or organs. The idea is that this test will indicate how prepared a cyclist is for long and high-altitude races like the Giro d’Italia—events that require participants to summit mountains above 2,000 m, where levels of