Getting a medical certificate before starting a new job is pretty standard here. For most office jobs, it is mainly a formality (although they do note any spinal issues that might later be attributed to sitting down to long, etc). For others, it is essential, to document medical conditions that might be at a later date blamed on the employer/to show that the worker did not have said condition before starting. It offers protections for both parties.
When I worked at a clinical lab, the medical exams required before starting were impressive! Then again, I worked a few meters away from blood and tissue samples, so it made sense. I was also required to take a lot of extra vaccines!