One of the best methods of cross training and one of the least utilized is walking on the treadmill. Yes, I said walking. While I was at Columbia, we had a freshman runner diagnosed with a stress fracture in her lower back very early in the season. We assigned her to a very high volume walking protocol. She did this for six weeks until she was cleared to run. Six weeks later, she was a NCAA I Cross Country All-American, as a Freshman! She worked up to 50-90 minute walks on the treadmill. We would set the inlcine at 4.5% and the speed at 4.0 – 5.0 making sure to never alter he normal walking gait.