I saw a young kid at the CW Post Pratt Center gym today using a rope machine. He pulled on a thick black rope. He could adjust the resistance. As with all machines, too little resistance would have you using momentum, while too much resistance would have you go too slowly for any kind of cardiovascular burn. This machine uses the shoulder, chest and back muscles. Abdominal muscles are mostly secondary movers and stabilizers.
Disclaimer: None of the above information can be taken as a substitute for advice from a medical professional such as a physician.
My third book, Pocket Guide to Fitness, is available on www.louizapatsis.com, http://www.authorhouse.com, www.bn.com and http://www.amazon.com. If you look up my name on those Web sites, you will find my other books The Boy in a Wheelchair and Life, Work and Play: Poems and Short Stories.