Fitness evaluation symptoms and conditions

I am a 60 year old male. I have been on high dose Niacin for more than 12 years. 2 years ago I started taking the combination drug, Advicor. (Lipitor and Niacin) Up until this point, there were no side affects with the Niacin other than occasional flushing. Since starting on the Advicor I have noticed a gradual weakening of muscles, and occasional joint pain. I have recently increased my exercise, thinking this was part of the aging process. I have not worked out consistently for 2 years. I have not noticed much improvement in my conditioning in the past 3 weeks, and have in fact noticed my quadriceps feel as though there is a buildup of lactic acid. I also notice my heart rate does not climb very high before my perceived exertion is above 50%. I did a fitness evaluation today at the health club I go to. The trainer mentioned that he hears the same thing from a lot of people who are on Lipitor. He went on to say, there heart rate is usually 20 bpm lower when on the drug. I am going to be talking with my physician to see about getting off Advicor and going back to just the Niacin. I will increase my exercise and more closely watch my diet. I want to thank the folks who have posted.