I use the treadmill to help me with my running training and also to do power walks on days I want little impact.
When power walking, I spend 50% of the time on speed work, doing laps at either 5.2, 5.4 or 5.6 mph, with no incline, and 50% of the time on incline work, varying the speed and inclines constantly, each lap is different. So, last time I started at 4.6 mph and incline of 6, then decreased speed to 4.4 mph and increased incline to 8, then decreased speed to 4.2 mph and increased incline to 10, then combined 4.0 mph with incline of 12, and finally 3.8 mph with incline of 14 or 15, which is the max my treadmill will do. This targets the glutes fabulously, while the speed work hits the legs and glutes.
I love it and can do this for 6-7 miles at a time.
When I run, since I am still trying to get back into running, I alternate running intervals of 2, 3, 4, 5, 6, 7 etc minutes, with fast walking rest periods of 2 mins at 5.0 mph. I do less intervals as the interval length increases. So, 15 intervals when running for 2 mins, but 13 intervals when running for 4 mins, and down to 10 when running for 6 mins per interval. In addition, I increase the speed at which I run with each successive interval, so I gradually increase the demands paced upon my body. I always start at 6.5 mph and work my way up to 8 mph by the end. With this, I will cover a distance of 7-8 miles per session and I limit the running sessions to three times per week only. This allows my body rest time and a break from impact work.
This is how I use the treadmill. For me, it is not a time to plod away, at a passive pace, while watching TV. I push myself as far and as hard as I can to see results. I am someone who needs to push hard and I need to sweat. I do this instead of taking anti-depressants. It helps.
Clare