Ask the doctor: Is it dangerous for me to go over my target heart rate?

My resting heart rate is on the high side, and it rises quickly when I exercise. I am afraid to go faster than 2 miles an hour on the treadmill, and I don’t feel like I’m getting a real workout. Is it dangerous for me to go over my target heart rate?

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By the way, doctor: Can you tell me about the tests for liver and muscle side effects from statins?

I am 80 and am taking a 40-milligram Crestor pill every day. Recently I saw a Crestor ad that said blood tests should be done to monitor for the possible side effects of liver or muscle injury. Can you tell me something about these tests?

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