Lipitor, also known as atorvastatin, is a medication used to treat high cholesterol levels. According to the Mayo Clinic [3], one of the common side effects of taking statins like Lipitor is muscle pain or weakness. However, the sources provided do not mention any direct effects of Lipitor on heart rate during physical activity.

A study published in the Journal of Clinical Lipidology [2] analyzed the effects of atorvastatin on physical fitness in patients with high cholesterol levels. The study found that atorvastatin did not have a significant effect on heart rate or physical fitness in patients. However, the study was conducted on a small sample size and more research is needed to confirm these findings.

Another source [1] provides information on the pharmacokinetics of Lipitor. It states that Lipitor is rapidly absorbed after oral administration and reaches peak plasma concentration within 1-2 hours. The elimination half-life of Lipitor is approximately 14 hours. However, this source does not provide any information on the effects of Lipitor on heart rate during physical activity.

In conclusion, while there is no direct evidence to suggest that Lipitor affects heart rate during physical activity, it is important to note that muscle pain or weakness is a common side effect of taking statins like Lipitor. Patients who experience any unusual symptoms while taking Lipitor should consult their healthcare provider.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4679305/
[3] https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/in-depth/statin-side-effects/art-20046013