If you seek medical treatment for an injury you are having, you will likely get some general practitioner referral exercise treatments to perform.
General practitioner referral exercise will likely be slightly different than what a personal trainer would give you because they will be less focused on building straight muscular strength and more focused on injury or joint recuperation.
Practitioner referral exercise could also involve more work using rubber tubing for example, as this will be slightly less intense than free weight training. It will also provide constant tension throughout the movement so it may be a better way to promote strength in the ligaments and tendons.
Usually the movements that you will be recommended are ones that you can do in the comfort of your home; at least in the beginning of your treatment. If you were recently hurt then chances are this area of the body is a little weaker and it will be best to slowly work it back up to full strength. As time progresses then you will likely be directed to take your recovery to the gym where you will start applying more resistance to it.
If at any point you start experiencing pain while performing the activities that you have been told to do, ensure that you discuss this with the professional who is treating you. Never try and push your body too hard when coming back from an injury as you could end up setting yourself back much further.
Also be sure to keep up with the activities on a regular basis as directed by your physician. Too many people will start out doing them as often as they should however as the body part starts feeling better their frequency will drop off. This is a very bad thing to let happen, as while you may feel physically fine, all your muscle fibres and tendons will not likely be completely healed yet.
So take your assigned treatment seriously. It will enable you to get better quicker and get back to your normal workout routine as soon as possible.