I have questions, mainly with pushups and my bad back.  Regualr pushups put a strain on my back.  If I do them on the stairs, with my hands higher than my feet, will I still be benefiting or is a differant group of muscles being worked??

Any other ideas?  I really need to get my chest back into shape.

Sgtar15

That would change the angle 45 degrees and definitely work different muscles, but many would still be the same.

Keep trying things like bench or dips to find something that will work your chest but not put much strain on your back.

Strengthen the abs.  I know they suck, but a lot of back problems (other than those related to severe injuries) are related to weak abs.  If your abs are not very strong, a LOT of stress is put on your back.  If you have strong abs, it helps to disperse any weight (that of your upper body, or anything you are moving/carrying) over your whole frame.

As far as pushups on the stairs, yes you will still be benefiting, and yes some muscles will be different than regular pushups.  You might also want to try doing pushups on flatground, but with you knees on the ground (and your feet crossed & in the air) instead of regluar PU's.  This will work the same muscles, but should put less of a stress on your back (and unfortunately arms) than regular push ups.

better than the stairs, have you seen those giant "excer-balls?"  they are large air filled balls that most people are seen doing sit up on.
Well they are a great supplement to any calastetic because you need balance to use it which usually hits the mostly untapped obliques on the sides of your abs.  Do your pushups with your feet on the excer-ball you will not only strengthen your pecs, shoulders and tri's but the stabilization muscles in the middle of your body.

You'll see these at any good physical therapist office.

You can also do pushups with your hands on the ball.  Having to stabilize your side to side movement also helps strengthen and stabalize your midsection.

Doing pushups on stairs would tend to put more emphasis on the lower part of the pecs, like decline.  But, you are not pushing nearly as much weight as a regular pushup, as most of the weight is shifted to your feet.  

Strengthening your ABS is great advice.  Train your lower back as well though.  Lay on your stomach and lift your legs and upper body off the ground and flex your back, hold for 10 seconds.  Repeat 3 times.  If this does not hurt(the bad kind of hurt), then gradually increase time and sets.  Do crunches instead of situps, and eventually, see if you can do regular pushups again.

If the pain persists, go see a doctor.