Lipitor, also known as atorvastatin, is a medication used to lower cholesterol levels in the blood [1]. According to a study published in the Journal of Clinical Lipidology, statins like Lipitor have been shown to cause muscle-related side effects, including muscle weakness and fatigue [2]. However, the study also suggests that these side effects are rare and occur in less than 5% of patients taking statins. Another study published in the Journal of Cardiovascular Pharmacology found that atorvastatin did not have a significant effect on muscle strength or endurance in patients with high cholesterol levels [3].

It is important to note that while statins may cause muscle-related side effects, the benefits of taking the medication to lower cholesterol levels may outweigh the risks. Additionally, the effects of Lipitor on muscle strength for swimming specifically have not been studied, so it is unclear whether or not the medication would have an impact on this particular activity. It is recommended that individuals taking Lipitor or any other statin medication speak with their healthcare provider about any concerns regarding muscle-related side effects and their impact on physical activity.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463373/
[3] https://pubmed.ncbi.nlm.nih.gov/25093910/