Professional Sprinter/track athletes use them. I've read several articles on this and have talked to numerous coaches. It's kind of hard to describe but i'll give it my best:
You can set a frequency on these machines to pulse every certain amount of seconds. Track athletes time exactly how long it takes to take 1 stride. They then set that time in the machine. All of the pads are set up to hit their hamstrings, glutes, quads, calves, and abs (hence the major muscles in sprinting). Basically the shock or pulse simulates the ground contact and stride frequency. This method is used once, sometimes twice a week, and is a favorite in rehabilitation workouts. I have not personally tried this but do have some friends who have and said the results were very good in helping them with ground contact and shaving time off their runs. I plan to try this sometime in January. Also, keep in mind that this isn't a $250 6 pad machine. They normally use 12-20 pads which is quite expensive. Hope this makes sense and helps a little.
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