Lipitor is a brand name for the drug atorvastatin, which is a medication used to lower cholesterol levels in the body. According to the sources provided, muscle-related side effects are known to occur with the use of atorvastatin, but chronic muscle strains specifically are not mentioned.

One study [2] found that statin-induced myopathy, which is a muscle disorder caused by the use of statins, including atorvastatin, can cause muscle pain, weakness, and tenderness. However, this study does not mention chronic muscle strains as a symptom of statin-induced myopathy.

Another source [3] suggests that muscle pain is a common side effect of statin use, including atorvastatin. The article explains that this pain can range from mild discomfort to severe muscle damage, but it does not mention chronic muscle strains specifically.

The drug patent information [1] for Lipitor does not mention chronic muscle strains as a known side effect of atorvastatin. However, it does list myalgia, or muscle pain, as a common side effect.

In conclusion, while muscle-related side effects are known to occur with the use of atorvastatin, including muscle pain and weakness, chronic muscle strains are not specifically mentioned in the sources provided. It is important to consult with a healthcare provider if experiencing any concerning symptoms while taking atorvastatin or any other medication.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4972163/
[3] https://www.health.harvard.edu/pain/managing-statin-muscle-pain