Walkthrough to explain unusual information

I am designing a medical application related to physical rehabilitation and I have hit a wall.

I have several screens in which the user will do several physical exercises - their rehab training. The screen is field with a lot of information like current progress, repetitions, set, angle at which their movement is tracked (through some third party device). I need to find a solution to explain what every information on the screen represent and how it interacts with the user's physical exercise.

Some of the information is more obvious, i.e. the repetitions as they are displayed as (rep: 2/5) but some of them may be more confusing (i.e. what those angles represent).

Taking into account that this is a closed circuit app*, that the users may not have any previous experience regarding rehabilitation training and that the age demographic goes up to 60 years, would a walkthrough of several steps fit this scenario? (with an option to skip and return to the tutorial at any time)

• the app is available on the AppStore but it is useless without the third party devices therefore no random user will download it

I am asking this question as I have seen a lot of guides/tutorials/tips/advices on the web suggesting to avoid at any cost any possible walkthrough. While I understand this for general gestures, I believe that in this case no general user may be familiar with the information displayed unless they are having a background in the medical field.

I am looking forward to your answers.