If you have a strong couch, and are fit and confident, try this.
Secure the back of your ankles under the couch. Keep your head, neck and back straight. put your hands behind your head with elbows open. Lower your body one to two feet and return. Primary muscles used are your hamstrings. Stabilizer secondary muscles used are your abdominal muscles. Do this for four sets of ten repetitions.
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.