Please get to the DR to get an offical check-up!

Long story short, my mother was diagnosed with a ventrical arythmia (completely mispelled, but I'm feeling to lazy to look up the correct spelling).

She's now on meds to help control the problem.

She's never been a cyclist, but both before diagnosis/treatment and after diagnosis, she's remained active in doing some sort of cardiovascular activity multiple times a week.

Her DR's encourage activity - it will only help her. When her blood pressure increased, they did suggest that she stop weight lifting untill it was back under control.

But nothing can subsitute for talking to your DR about all of this!