Tachycardia with Mild Exercise

I am a senior who exercises five times weekly.  My heart rate is always around 122 even after 40 minutes on the treadmill or bike.  yesterday after only 3 minutes it was 135.  I panicked and went to the treadmill where after 1 minute it was 150.  One of the fitness trainers took it manually and it was 156   I raced home in a panic and called my nephew who is parametic.  He told me not to worry as I had no other symptoms.  I called my internal medicine doctor who said he was not concerned.  It stayed high for one hour!!!  I realized I had forgotten to take my Prilosec yesterday morning.  Do you think I need to be concerned.  It caused me a lot of worry.  

[curmudgen]

If your doctors aren't concerned then try not to worry.  That said, a pulse of 122-156 is high.  Any chance you are becoming dehydrated?  If you take prilosec for GERD then perhaps you have a mild inflammation of your esophagus which in turn is irritating your vagus nerve causing an increase in heart rate.  If this was a one time occurrence then don't panic....monitor it in the future.