Nancy, according to Cathe, arm movements add 12% to your workout. They help increase the cardio.
I wear a HRM when I do elliptical and my HR, when I am doing intervals, can go as high as I want it to. 170 is the anaerobic threshold for me, so that is pushing pretty hard.
I usually go about 70rpm on a resistance level of 9. I use the arm handles and really push and pull when I want to increase how fast I am going.
I think the poster above who said she is working hard and sweating IS getting her HR up. You would have to be hardly going at all to NOT get your HR up. JMHO.