Smoking-induced elevations in blood carboxyhaemoglobin levels - Effect on maximal oxygen uptake

Many people engage in physical activity to reduce their cardiovascular risk associated with smoking. These people should be made aware of the metaboli c and cardiorespiratory changes induced by chronic and acute smoking and, i n particular, the exercise ramifications of increased levels of blood carbo n monoxide (CO). Smoking-induced elevations in the CO content of the blood can reduce exerci se tolerance and maximal aerobic capacity. Smoking also increases the relia nce upon glycolytic metabolism during exercise. Together, these factors con tribute to earlier fatigue in smokers compared with nonsmokers who exercise . Similar effects upon exercise tolerance are noted in those who inhale env ironmental tobacco smoke.