My client recently reinjured a knee that’s been problematic for a long time. It’s a severe sprain and her wedding is only 6 weeks away. She is bummed to say the least and desperate to continue to lose weight up until the big day. Once the swelling subsides I can have her on her feet but for the time being we will be seated for most of the workout. We will focus mostly on upper body and I could use ideas for either position (seated or standing) that will keep her heart rate elevated!!!
Upper body ergometry is a great idea, however, after her six weeks are over, I would collaborate with her physical therapist to make sure that how you are training her is safe and effective.
As you haven’t indicated what type of knee injury it is, it is a bit difficult to give a suggestion.