Thanks for writing to Health Care Magic
There can be enlargement of heart wall with excercise. The condition is called athlet's heart as u described. This is a benign condition and doesnot require treatment. However this needs to be strongly confirmed as there are several other dangerous causes of increased thickness of cardiac muscle
. These need to be ruled out. Get all the investigations done. Wait for a period till it is confirmed that the enlargement of ur heart doesnot have any serious causes. After everything is ruled out u can get back to ur daily routine.
Hope this helps u
Thanks and regards