Outside running on a hard surface repeatedly and over doing the frequency of the exercise is a contributing factor. On a treadmill the problem is exactly the same and has the same name. When your shins hurt it's because of the running that you're doing not the surface you're doing it on. This is the case even when the surface is the running belt of a treadmill.
You may not expect shin splints on a treadmill and it's not reported so often. But that's because when people have experience in running they move from the treadmill onto outside. The treadmill is only used in special circumstances like speed training or when outside conditions like the weather doesn't favor it.
There is a further reason that it can happen on treadmills too and that is because the terrain you're running on never changes. Outside your legs have to make adjustments for the terrain you're running on, even when this is hard concrete. But on a treadmill the running action is the same every time. You're repeating the same steps over and over which can exacerbate running injuries like shin splints.
What shin splints are
Shin splints is a collective term for any injury occurring to the lower leg caused by running. It's normally on the front of the tibia which is the bone we feel the pain and tenderness on. But it can occur on other parts of the lower leg including the back where the fibula is. We all know the feel and pain of shin splints on the front of the lower leg.
They occur because the impact of the running surface is no longer being absorbed properly by the legs and feet. This is typical in training that's become more intensive or if the footwear needs replacing. Your running shoes may have lost their impact absorption or you may need to have a week of less intensive running or alternative exercising like an elliptical.
How to treat shin splints
As mentioned before your running shoes may need replacing and if they do, get them fitted using a speciality running store. This way you get the shoes that are right for you and will make your gait more efficient and less likely to stress your lower leg. There is the classic R.I.C.E treatment for soft tissue injuries. This is rest, ice, compression and elevation.
Remember to warm up and cool down before and after exercising. Stretching is a good way of treating shin splints and to help prevent them coming back again. There are shin stretches you can do where you sit on your feet with your legs bent in front of you and put pressure on your heels by leaning back. An advanced version is where you are in the same starting position you lift your knees.
This is not always convenient but will help the injury and reduce the pain and swelling. Try some strength exercises on the lower leg to help strengthen the muscles that support the area. Finally it's tempting to run through it and we've all done it but to prevent it getting worse and developing into stress fractures some treatment is needed.
I do my running exclusively on a treadmill and I have experienced shin splints. They've occurred when I've completed a long run. It doesn't happen often but I know when I've over done it. Your weight is a factor as your knees and shins have to take every pounding you give them. Fortunately you can just take a day off or have an easy run and you should recover.
Shin splints are far more common from running outside and can get worse if you don't do something about them. As long as you wear good running shoes, stretch before and after you workout and do strength exercises on the lower leg, shin splints doesn't have to be something that defines your routines. You can easily continue your running with some thought and care.