Sure, smoking is bad for you -- but what happens when you combine it with something really good -- like running eight miles a day? Do you get a healthier smoker? Or an unhealthy athlete?
It's one of those is-the-cigarette-half-smoked-or-half-unsmoked conundrums. And there's no definitive answer.
"If people can quit, that's the best thing," says Dr. Robert Sallis, director of sports medicine at Kaiser Permanente Medical Center in Fontana. That seems obvious, but Sallis explains that many of the risks associated with smoking are immediately and dramatically reduced upon quitting. Then he adds: "If you can't stop smoking, exercise will mitigate some of the effects."
Lung cancer is a prime example. Although smoking increases the risk of the disease, exercise seems to provide a protective effect. In a 2006 study published in the journal Cancer Epidemiology Biomarkers & Prevention, women who were current or former smokers and had high levels of physical activity were less likely to develop lung cancer than those who were more sedentary.
"When you exercise, that improves your cardiovascular function and your HDL cholesterol, and generally, it's just good for you," says Dr. Stanton Glantz, professor of medicine in the division of cardiology at UC San Francisco. "So if you smoke and exercise, you're going to be better off than if you smoke and don't exercise."
But, he adds, smoking may also hamper athletic abilities. "The balance is going to depend on how much you smoke and how much you exercise. But I can tell you unequivocally that people would be better marathoners if they didn't smoke."
Inhaling cigarette smoke causes a number of effects in the body that can affect performance. In the lungs, it increases tissue inflammation, narrowing airways and allowing less oxygen to the body. Since working muscles need more oxygen, this could result in less strength and energy during exercise.
A study examining the effects of smoking cessation found some fitness improvements after a week. Eleven young men who smoked about a pack a day for 3 1/2 years were subjected to several tests while on a stationary bike before quitting, and then a week later. The 2000 study, published in Medicine & Science in Sports & Exercise, showed that pulmonary functions showed no significant improvement, but oxygen concentration considerably increased, and exercise time was greatly extended.
"Part of what's happening is the physical irritation" to the lungs, Glantz says. "The industrial solvents that are in cigarette smoke -- benzene, acrolein -- and then there's the particulate matter and the tars. You're bathing cells in industrial-grade solvents and it's going to reduce oxygen transport."
The effects of carbon monoxide in cigarettes while smoking and afterward take a tremendous toll on the body, says Dr. Zab Mosenifar, medical director of the Women's Guild Lung Institute at Cedars-Sinai Medical Center. It compromises the ability of the blood's hemoglobin to transport oxygen from the lungs to the body, especially the muscles, during exercise.
Carbon monoxide molecules attach to hemoglobin molecules, hampering the hemoglobin's ability to pick up oxygen from the lungs and deliver it to the body. "This robs the muscles of extra oxygen," he says. Nicotine, Mosenifar adds, is a vasoconstrictor, narrowing the muscular wall of blood vessels, slowing blood flow. Over time, this can cause permanent damage to the arteries.
After years of smoking, some people may contract chronic obstructive pulmonary disease, a combination of emphysema and chronic bronchitis that causes irreversible lung damage and airway obstruction.
So why do some smokers who exercise say they feel little or no effects from cigarettes? Health experts say part of it might be a degree of denial. Age, how long they've been smoking and how much they smoke are factors. Genetics and physiology might also play a part in how the body handles the damage from cigarette smoke.
Lung and cardiovascular function have to be fairly compromised, says Glantz, in order for people to notice a change: "A lot of these effects accumulate over time," he adds, and smokers may not feel them until they have tremendous trouble breathing, or serious heart problems.
Men and women who exercise might get tired or winded sooner or feel their legs cramp up, but if they've been smoking for a long time, and with no significant breaks in the habit, Glantz says, they may have nothing to which they can compare it.
The good news, he adds, is that most cardiovascular effects begin to reverse with a few days of quitting. "So if you were to take an athlete and have them quit for a week or two and have them do the same run again, on the average they'd do better." Some acute effects from smoking, such as lung tissue inflammation, can go away permanently, while others, such as cancer risks, linger.
"Two cigarettes a day is enough to have adverse cardiovascular effects," says Glantz. "In terms of the underlying biology, there's no question that it's affecting their cardiovascular systems in ways that are affecting their ability to exercise."
Mosenifar, a marathoner, doesn't buy the argument that regular exercisers can use their healthy habits to justify their smoking. "It's like someone saying, 'I steal, but I also go to church or synagogue, so I'm doing something positive.' They're two separate issues. People need to do some serious soul searching."