Some drugs are tolerated (nicotine and caffeine) and used by athletes. Smoking and chewing tobacco are common sources of nicotine, while persons with acute reactions to caffeine can be influenced through "acceptable" levels of associated drink and food ingestion. These drugs have an effect upon performance.
Addiction results in two basic extremes of metabolism, one in the presence of the drug, the other in its absence. When the dependency habit occurs independent of training times, applications to training are exposed to a shifting basic metabolism. …
