Lipitor is a brand name for atorvastatin, a medication that belongs to the statin class of drugs, which are used to lower cholesterol levels in the body [1]. According to a study published in the Journal of Clinical Lipidology, statins have been associated with muscle-related side effects, such as myopathy, myalgia, and muscle weakness, although the incidence of these side effects is relatively low [2]. Muscle-related side effects of statins can potentially affect one's ability to engage in physical activities such as stretching routines.

However, not everyone experiences these side effects, and the severity of the side effects can vary from person to person. In addition, there are ways to manage muscle-related side effects of statins, such as switching to a different statin, reducing the dose, or taking a break from the medication [3].

Therefore, if you are taking Lipitor and experiencing muscle-related side effects that are affecting your stretching routine, it may be worth discussing your options with your healthcare provider. They can help determine if the medication is causing the side effects and recommend alternative treatments or adjustments to your current medication regimen.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463373/
[3] https://www.health.harvard.edu/pain/managing-statin-muscle-pain