No-impact workouts?

I have been an avid runner for the past year or so, but over the past few months I've had a nagging stress fracture that has kept me from running. As soon as I stopped running I began biking and ocasionally swimming, but I have been steadily gaining weight ever since, putting me about 15 pounds over my ideal weight.

Now, my question is, what kind of workouts are there that have calorie burn rates similar to running? I am not able to do anything with impact due to my fracture.

Thanks for any input!

Sean

I would recommend swimming for sure.  :)

Cross country ski machine? I  did not look it up to compare the numbers...

WEight lifting -- HEAVY

I burn 500 - 600 cal in an hour of weight lifting vs 300 - 400 cardio.  Also some elliptical 

I'm agreeing with sweetjurney. Swimming burns a ton of calories and is very low impact.

I second dbackerfan: weight lifting. If heavy seems like too much, start with what you can do, and work up.

when i stress fractured i went to spin class (and the eliptical) i was also doing body pump i didn't gain weight.  and i went back to running at a quicker pace i think from body pump and spin classes.

good luck to you.

Bikram yoga,  one of the reasons why I go is because it burns as many calories as running.  Each class is  90 minutes in a room heated to 105 degrees.  It's definitely a challenging workout.