Cigarettes have been shown to severely increase your risk of serious health problems in regular smokers and those who have been exposed to large amounts of second-hand smoke. Some of these health risks include cancer, emphysema and bronchitis. For this reason, it's not surprising that smoking can also have negative effects on athletic performance.
Lack of Blood Oxygen
When you exercise, your heart rate increases in order to meet the blood oxygen demands of your muscles. Generally, the faster your heart rate, the more oxygen your muscles need. Cigarettes contain carbon monoxide, which binds to the hemoglobin in your blood more effectively than even oxygen, which means that your muscles are unable to get the oxygen that they require during exercise. This makes your heart work even harder.
Narrowed Blood Vessels
In addition to reducing your body's oxygen intake, smoking also narrows your blood vessels. This occurrence makes pumping blood throughout your body a slower and more difficult process while playing sports. It also puts extra strain on your heart every time it pumps, because it has to work harder in order to supply your body with the blood oxygen it needs to function.
Increased Resting Heart Rate
Your resting heart rate is also increased from smoking. Your resting heart rate is how many beats per minute your heart produces when not being active. This number is greatly increased in smokers due to the extra work your heart must endure in order to meet all physiological demands of your body. This also means that when exercising, your heart rate could possibly rise to dangerous levels in order to meet the physical demands you're requesting of it.
Airway resistance refers to the rate at which air enters and exits your lungs. According to The Non-smokers Movement of Australia, one inhalation of a cigarette can increase this resistance by up to three times. Other factors such as tar build-up, inflamed mucous membranes and reduced air capacity will also increase airway resistance, making it more and more difficult to produce the oxygen your body needs when playing sports.