There are pros and cons to running indoors on a treadmill. One of the pros is that it is a great environment for improving your running form. An effective trick is to run as close to the front of the treadmill as you can. This helps teach you to land with your foot closer to your center of gravity (hips).
The top image is before and the bottom after. In the before image the runner is significantly heel striking and the knee looks to be locked out at impact. This greatly increases impact and braking forces, and with time will most likely lead to overuse injuries. In the below image the runner was instructed to run as close to the front of the treadmill as possible. By doing this the runner did a better job of not over-striding and their knee was slightly bent at impact. A win-win!
If you are curious to see how this can help out your running, stop by the store and we will be happy to help you out. To learn more about Good Form Running check out… www.annarborrunningcompany.com/good-form-running