After the
implantation of pacemaker, there is no problem and you mother can carry out all her a activities.
Now coming to your case, extreme training would lead to
bradycardia and your resting pulse rate will go low, which is rather a sign of healthy heart
However 35 is too low, I would suggest you to get a 24 hour holter, which will help us detect pauses, which may be the reason of your
dizziness , and during the day do maintain a chart for activities, to see if during exercise your
heart rate goes up as expected, other test is Treadmill
stress test for chronotropic competence, which too would give up an idea of the increase in heart rate with exercise, if it doesn't increase adequately with exercise means that the heart is incapable of the same, and that may cause dizziness. .