The main way in which smoking hurts your health and performance at the gym is by decreasing lung capacity. When you work out, either with cardiovascular exercises or by weight training, you should do it with a level of intensity such that you breathe hard. Smokers begin with a lower capacity in general, so even if your muscles feel as though they can lift more weight, your lungs can't. Decreased lung capacity results in the transportation of less oxygen to your body, including your muscles, so you can also put yourself at risk for serious injury. Because of the high amounts of carbon monoxide you are inhaling when you smoke, you encourage your brain and cells to absorb more carbon monoxide than oxygen. This lack of oxygen prevents your muscles from operating at full potential.

If you are competing, smoking has bad cosmetic consequences as well. The tar not only blocks air from your lungs, but also turns your teeth yellow, and although your smile is not a part of the judging, overall appearance can make or break you. Smoking gives the impression that you simply don't care. Cigarette smoking also causes your skin to be less elastic, resulting in more stretch marks if you are putting on weight quickly. Unless you have a lot of time and money to spend getting the stretch marks surgically removed with lasers, they're pretty permanent.

It's a hard process, but quitting shows that you truly want to become a top bodybuilder. There are many programs available to help you quit, and chances are that your friends and family, who are probably sick of smelling like smoke, will help motivate you to stop. When you quit smoking, you increase your chances of building and maintaining more muscle mass, improve your overall health and appearance, and become a better role model to the young bodybuilders around you. Teens with parents who smoke are a lot more likely to light up as well, so if not for yourself, quit smoking to set a better example for the sport.