Can excessive exercise damage the heart

I am a 60 year old female, teetotal, no medication, gave up light smoking 30 years ago.  I am normal weight and have exercised regularly for many years.  Recently I increased my exercise routine a bit, averaging an hour of cardio working up to the upper limits of my training zone (60-90%) 5-6 times a week - no breathless or dizziness or nausea.  However, on one occasion recently I had transient and not very severe central chest pain after 45 mins and another time I had a swooshing gurgling sound under my left breast again after 45 mins. For the past couple of months I have also periodically had a flutter/vibration, lasting 5-10 seconds each time, in the left side of my chest, at rest and usually not in bed, working up to happening every 5 or 10 minutes during the day.   Blood tests (thyroid, glucose, iron, cholesterol, etc.) are normal and a resting EKG  showed saddled and slightly elevated ST segments in v5/v6.  I gave up all exercise for two weeks and then had an exercise EKG (slightly tall QRS complexes in v5/v6 noted more in recovery but otherwise normal with no physical ill effects).  By now almost all the fluttering had disappeared although I am still sometimes aware of my heart beat (slow at rest - under 60 pbm).  I then had an echo which showed normal LV size but mild mitral regurgitation.  I wore a holter monitor for 24 hours and am waiting for the results (I did not feel any fluttering during that time).  My question is whether I could have caused the fluttering by excessive exercise as it has virtually disappeared now that I have rested several weeks and resumed only mild exercise.  Could I have damaged my mitral valve with excessive exercise as well?  Now that it is damaged, what is a safe level to exercise?  What should be the maximum heart rate to reach during a session and how often per week?  What is the likely progression of MR?  Barring any other unforeseen events, will I eventually need surgery?  Thanks for any help you can provide.

[Michael J. McWilliams, M.D.]

My question is whether I could have caused the fluttering by excessive exercise as it has virtually disappeared now that I have rested several weeks and resumed only mild exercise.

Excessive exercise is not good.  What is considered excessive depends on the individual.  It is best to listen your body and if tells you back down, slow down.  Once your doctor tells you it is ok to exercise, exercise in moderation is probably best.  It is difficult possible impossible to define what constitutes "moderation" versus "excessive."  It varies from person to person.

Could I have damaged my mitral valve with excessive exercise as well?  

Mild mitral regurg is probably not clinically important.  You did not cause it with exercise.

Now that it is damaged, what is a safe level to exercise?  

I doubt you hurt your mitral valve with exercise.  The you have probably had that for a very long time.  Like I mentioned above, I cannot really define "safe" because it varies from person to person.  Ask your doctor what they think.

What should be the maximum heart rate to reach during a session and how often per week?  

I don't have enough information to answer a question like that.  Ask your doctor.

What is the likely progression of MR?  Barring any other unforeseen events, will I eventually need surgery?

If you have mild mitral regurg, the likelihood of you needing surgery is very, very low.  It should be followed at the discretion of your doctor, but it is unlikely to progress if your other tests are normal.

I hope this helps.