the knee problems stem from a bout with Cancer 2 years back. i had a type of sarcoma on my thigh bone and went though surgery plus 40 weeks of chemo that left my bones/muscles a little rough. but i will look to mix things up a bit. i go to normal gym so i will change things up. i have been doing that somewhat. usually i am cycling 45 minutes, treadmill for 5 minutes or so and sometimes elleptical machine for a few. i might do the stair climber instead of the elliptical. any opinions on that?