How do these two compare? I have a Wii fit and I've been doing 20 minutes of running on the spot (once in a while I lap the pool table). Eventually I would like to go outside and run with my dogs when it's warmer. Because I can run on the spot for 20 minutes does that mean I should be able to jog outside for 20 minutes? Obviously there are some differences so I'm unsure.

Good question! I have no idea of the actual calories burned either way, but for me, I actually find it more difficult and tiresome running in place rather than moving forward. My feet and my knees tend to hurt more when running in place, but even if I move a little (like run around the sofa when playing Wii Fit instead of running in place), my knees and feet do not complain as much (though I do get a bit dizzy!). One thing I found very interesting on Wii Fit, though: my % at the end is much higher when I run in place than if I run around the sofa. I find that very strange.

Well I'd say running, specifically outdoors, is more difficult so I wouldn't expect to be able to run 20 minutes outside. What I'd recommend though is looking at something like the C25k program to train yourself to run.

Running in place has no wind resistance and no hills. At any given cadence it's easier than normal running.

This is probably because when you are running in place you land on your toes, with your leg straight below you putting pressure on your knee as well. When you're moving forward, your leg is slightly in front of you and you land on your heel.

I have done the jogging in place on the Wii Fit too. It's nice being able to watch something on TV while the Wiimote keeps me updated on how much longer I have to go. I did find however that when I started jogging outside, the jogging in place I was doing with the WiiFit really didn't transfer much. I could do the WiiFit jogging for 20-30 minutes fairly easily, but still became quickly winded when I first started jogging outdoors. It's just different I suppose. I am slowly building my way up with jogging outside though. I love being outdoors, so I find it really enjoyable. But I still do the WiiFit on cold and rainy days.

There are big differences between running outdoors, on the treadmill and on the spot... Outdoors you have all the resistances, hills, wind, etc., on the treadmill, you have the machine propelling you, on the spot, as Ashley said «... you are running in place you land on your toes, with your leg straight below you putting pressure on your knee as well.» BUT doing something is better than doing nothing... If it gives you sore knees, run around the living room, pool table or your significant other ...

I agree it's a different movement... I actually get foot cramps running on the spot sometimes and actual running makes them go away. I'm really anxious to see how I would do with actual running but there's no way I'm going to a track and there's to much snow to go outside. I think by summer I'll be more ready for it. Hah! Then I'll give my Border Collie cross a run for his money!

Maybe, try some power walking. You said you had a dog, so maybe try to walk a bit faster (burns about the same amount as a slow jog!) when you walk your dog. That way, you get a great workout--and so does your dog. Personally, I started out running by alternating between power walking/running around a local track until I got the hang of it. It takes a bit to build up the ability to run even one lap, but once you get it, you're a runner!