Treadmill running vs running outside

Does anyone know why I would be able to run on a treadmill without much shin pain but when I run outside I have aweful shin splints? I bought new Asics Gel 1130 and also inserts which helped. I still am having some pain though. I am a beginner of course, running only a max of about 1/2 mile at a time.

I find it much easier to run on a treadmill than in the neighborhood.    The treadmill must have more give to it than sidewalks or roads.  If you are running on pavement, I'm sure that is part of it.  I started out running in the neighborhood last spring & by summer the humidity was killing me.  Once I joined a gym I was able to really start working on my running goals; I really love knowing how fast I'm going, and how far I've gone.  I've never had shin splints, but my daughter used to get them periodically. 

Thanks for your answers. I too thought that maybe it was the surface. I live in a smallish town in the TX Panhandle and do not have a running store...I did do some research and bought what I thought to be the right shoes for me...now I think I may have to drive 4 hours away and get to a real runners store.

Before you drive four hours to get new shoes, do some research at Runner's World and see if you can determine your own gait type.  Runner's World has good advice on this.  Another good option is to have someone video you running from the front and back and see if your ankles are bending in one direction or the other.

Almost assuredly the treadmill is softer than running outdoors.  Shin splints CAN be caused by tightness in your calf muscles.  It pulls on the muscles of the shin.  It could also be a stress fracture (unlikely if you are not experiencing it on the treadmill).

I recommend you do calf and toe raises and maybe a few other exercises to strengthen your shins and calves.  Maybe do a run/walk thing until your legs build strength.  Roll you calf muscles with a Stick or Tiger Tail.

Good luck.  When all else faiils, seek professional help!

There is no doubt that a treadmill has more cushioning that outside.  The closest you'll come outdoors is to run on grass.  Also as mentioned, if you are beginning you could be suffering from something similar to shin splints... or a warning that your body will develop them if you don't slow down and give your legs time to adjust to the exercise.  You haven't described where the pain is, so it's difficult to say whether it's the muscles at the front of your leg... most likely the tibialis anterior or in the bone. 

As Wes mentioned, if you plan to run it's always a good idea to have your gait analysed.  Buying the most expensive shoe doesn't mean it'll help you.  Someone needs to analyse whether you pronate or supernate and what your natural stance is.  Then a suitable shoe can be found for you.