Intensity in pregnancy: the talk test, not heart rate
Exercise in pregnancy used to be capped by strict heart-rate limits. Today, the guidance is to go by perceived effort and the talk test, which are more reliable and individual.
What the talk test is
If you can talk in sentences while exercising, the intensity is probably fine. If you can't get a sentence out, ease off.
How a kinesiologist helps
A kinesiologist tracks your effort and adjusts intensity across trimesters, safely and without guessing.