1) Upright Bike
Calories Burned: 350-400
Pro: It's fairly easy to get the hang of, so most people can feel comfortable right away. It's also less stressful on the knee joints than weight-bearing equipment.
Con: No matter how ergonomic the seat is, low-back stress from spinal compression can be a problem.
2) Treadmill
Calories Burned: 450-475
Pro: Walking and
running are natural activities, so most people can do them for a long period right away.
Con: Rapid increases in speed and/or incline can change gait patterns and cause injury. Use very gradual speed increments, don't go above a 3%-4% incline and use speed as the primary intensity adjustment.
3) Recumbent Bike
Calories Burned: 350-375
Pro: A wider seat with a backrest makes this a better option than the stationary bike for anyone with low-back problems.
Con: Sitting for long periods can still be uncomfortable for some people. Also, people with foot control problems such as foot drop (a weakness in the ankle and toe muscles) may have trouble because the feet can slip out of the pedal straps.
4) Elliptical Machine
Calories Burned: 420-429
Pro: It's less weight-bearing than a treadmill, and it's fairly easy to use. Plus, many come with upper-extremity attachments so you get a better overall workout.
Con: Depending on your size, the movement arc on the machine can be either too large or too small. A small person may be placed in an awkward position, throwing off the natural gait; a large person may not get enough of a stride for a good workout.
5) Stair-Stepper
Calories Burned: 430
Pro: It's challenging because essentially you're climbing uphill the entire workout. It's also less weight-bearing, so it can be an excellent rehab for most knee injuries.
Con: There can be a long learning curve. People often hold on way too much with their arms, and that can take away 30% of the effort. Also, a lot of people lean too far forward, which puts them in a poor postural position that can lead to injury.

