Are there any cardio exercises for seniors that mainly use the arms and do not involve walking, biking, using a treadmill, or swimming?
There is not much option for this kind of cardio. You can go for aerobics in the water maybe. There are a few practices you can do in water that is not so intense. Other than that you can do chair exercises. Check this youtube video out so you know how to do it. https://www.youtube.com/watch?v=KbFz38FUuiA