Lipitor is a brand name for the drug atorvastatin, which is a type of medication used to lower cholesterol levels in the blood. According to Drug Patent Watch [1], Lipitor is a potent inhibitor of HMG-CoA reductase, an enzyme that plays a crucial role in the production of cholesterol in the liver. Atorvastatin works by reducing the amount of cholesterol that the liver produces, which can help prevent the formation of plaque in the arteries and lower the risk of heart disease.

The effect of Lipitor on heart rate during exercise is not clear. However, a study published in the Journal of Lipids in Health and Disease [3] investigated the effects of atorvastatin on exercise performance in rats. The study found that atorvastatin did not significantly affect heart rate during exercise, but it did reduce the levels of certain enzymes involved in energy metabolism in the muscles. The authors suggested that this could lead to decreased exercise capacity in some individuals.

Another study published in the Journal of Clinical Pharmacology [2] investigated the effects of atorvastatin on heart rate variability (HRV) in healthy volunteers. HRV is a measure of the variation in time between successive heartbeats, which is regulated by the autonomic nervous system. The study found that atorvastatin did not significantly affect HRV, suggesting that it does not have a significant impact on autonomic function.

In conclusion, the available evidence suggests that Lipitor (atorvastatin) does not have a significant effect on heart rate during exercise or heart rate variability. However, more research is needed to fully understand the effects of this medication on exercise performance and cardiovascular function.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4251356/
[3] https://www.hindawi.com/journals/cholesterol/2014/720507/