Lipitor, also known as atorvastatin, is a medication used to lower cholesterol levels in the blood. According to Drug Patent Watch [1], Lipitor is a statin drug that works by inhibiting an enzyme involved in cholesterol synthesis, thereby reducing the amount of cholesterol produced by the liver.

While statins have been associated with muscle-related side effects, including muscle pain and weakness, recent research suggests that they do not have a significant negative impact on running performance [2]. In fact, a study published in the Journal of the American College of Cardiology found that statin use was not associated with decreased running performance in recreational runners [2].

However, there may be a fitness downside to statin drugs, as reported by The New York Times [3]. According to the article, statins may reduce the body's ability to adapt to exercise, potentially limiting the benefits of physical activity. This is because statins can interfere with the production of a molecule called coenzyme Q10, which is involved in energy production in the body. As a result, some experts recommend that individuals who take statins also take a coenzyme Q10 supplement to help counteract this effect [3].

In conclusion, while Lipitor may have some muscle-related side effects, it does not appear to have a significant negative impact on running performance. However, there may be a fitness downside to statin drugs, as they can interfere with the body's ability to adapt to exercise. Individuals who take statins may want to consider taking a coenzyme Q10 supplement to help mitigate this effect.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.runnersworld.com/news/a20859227/statins-wont-hurt-your-run/
[3] https://www.nytimes.com/2017/01/04/well/move/a-fitness-downside-to-statin-drugs.html