Hi Naomi. With clients who present with medical conditions such as the ones you mention in your question, I would definitely get a physician’s clearance and authorization for them to train with you before working with them. It’s the prudent and professional thing to do in my opinion.
Yes for any medical condition or risk factors that surpass guidelines it is imperative to not only get a release from their doctor but to have an ongoing relationship with the physician for future questions or situations.
It is our responsibility as professionals to keep the best interests of our clients in mind.