The elliptical machine is a godsend for a lot of gym goers: it’s smooth, it’s not too nerdy, it feels like something approximating a normal motion. And for many it is, but for a pretty large percentage of people, it’s absolutely awful. The reason is quite simple: the elliptical machine has a pivot point that may be too small or large for a large number of users. If so, it forces the lumbar spine to flex and rotate through the cycle. Flexing and rotation of the lumbar spine is NOT a good thing, and WILL decay the discs of the lumbar spine. A video analysis of the low back during this activity will show the issue right away. If there’s motion in the lumbar spine, it’s TIME TO STOP. Use the treadmill instead.
Also, you aren’t burning the calories you think you are, as the caloric output is based on the spinup phase of the flywheel, not the maintenance of momentum…. which means you’re burning only about a 1/6th of what it says.