Cigarette smoking leads to many health hazards that all runners need to avoid. Firstly, the airway resistance within the lungs increases due to smoking. The process of oxygen absorption by the blood is also lowered. Plus, the physical endurance of the runner also decreases. All these effects can greatly restrict the performance of a runner. One needs to have healthy lungs when running so that they can take as much oxygen as they can from the surrounding air. When the oxygen is transported to the blood from the lungs, it travels to the muscles that are in use. Muscles can produce energy only when they receive a steady supply of oxygen. If the airways are constricted and absorption of oxygen by the blood is lowered, the muscles receive an inadequate supply of oxygen and cannot function properly. This would adversely affect performance. The person's endurance suffers and fatigue sets in.
Smoking of a cigarette could result in a three-fold increase in resistance of the airways. The mucus membranes also swell and this further elevates airway resistance. Cigarette smoke contains tar which coats the lungs and reduces the air sac's elasticity. This lowers the rate of oxygen absorption by the blood stream. Oxygen travels throughout the body as it adheres to the hemoglobin present in red blood cells. Carbon monoxide has a greater affinity to red blood cells and hence also binds to the hemoglobin. Elevated carbon monoxide levels can negatively affect the oxygen release from the blood into the red blood cells. This can affect the muscles of the heart and other parts of the body which are in need of oxygen. Exercise is known to improve oxygen uptake up to 20 percent. However smoking may decrease this effect by up to 10 percent. Studies have shown that smoking adversely affected physical fitness even in young individuals who were considered to be fit. Another study indicated that the physical endurance of smokers is lower than that of non-smokers or ex-smokers. These factors should be enough to indicate that running and smoking is a bad combination and one of the best decisions a runner could make is to quit smoking.
answered by G M