Hi,

Sometimes physio is looking to provide stability around a joint and isolate a particular muscle therefore the exercise can feel like it is not working particularly hard (ie a static quad where you are pushing the knee straight into the bed). Be sure to listen to the instructions of your physiotherapist in terms of the technique. The next thing to do is give them a quick call or email to clarify these questions. All physiotherapists on here will be working blind and have not seen the alignment of your hip/ knee or completed an assessment. The exercises you describe sound like strengthening exercises. Be sure to maintain good posture in your upper body so that you are not compensating with your back muscles ie leaning forward while bring the leg back.

Hope thats helped a bit!