The Applied Exercise Science Lab is seeking competitive cyclists aged 18-35 to participate in a project studying the effects of a low dose of carbon monoxide on exercise energetics. While toxic in high doses, low levels of carbon monoxide have been shown to have separate, beneficial effects. The experiment will consist of four separate sessions, which together will last a total of four hours. Your oxygen uptake and caloric expenditure during submaximal cycling will be determined and you will be offered a Total Hemoglobin Mass (THM) measurement.