Lipitor is a brand name for the drug atorvastatin, which is used to lower cholesterol levels in the blood. According to the National Health Service (NHS) [3], shortness of breath is a rare side effect of atorvastatin, which can occur in less than 1 in 10,000 people. However, the exact mechanism of how Lipitor affects breathing during exercise is not mentioned in this source.

A study published in the Journal of Clinical Medicine Research [2] investigated the effects of atorvastatin on exercise capacity in patients with dyslipidemia (abnormal cholesterol levels). The study found that atorvastatin did not significantly affect exercise capacity or respiratory function in these patients. However, this study did not specifically investigate the effects of atorvastatin on breathing during exercise.

Another source, Drug Patent Watch [1], provides information on the pharmacology of atorvastatin. It states that atorvastatin inhibits the enzyme HMG-CoA reductase, which is involved in the production of cholesterol in the liver. This inhibition leads to a decrease in cholesterol levels in the blood. However, this source does not mention any direct effects of atorvastatin on breathing during exercise.

In conclusion, while shortness of breath is a rare side effect of atorvastatin according to the NHS [3], the exact mechanism of how Lipitor affects breathing during exercise is not clear from the provided sources. One study found that atorvastatin did not significantly affect exercise capacity or respiratory function in patients with dyslipidemia [2], but this study did not specifically investigate the effects of atorvastatin on breathing during exercise. The pharmacology of atorvastatin is well-established [1], but again, no direct effects on breathing during exercise are mentioned.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463373/
[3] https://www.nhs.uk/medicines/atorvastatin/side-effects-of-atorvastatin/