The platform vibrates/shakes according to what the therapist sets. For people like me, who can't walk far enough (due to imbalance from neuropathy) to maintain muscle mass in the legs, the muscles there and in your core are strengthened when you simply stand in place keeping your balance against the degree of vibration. I'm sure it is helpful for a lot of other physical strengthening situations. My therapist has only had it for about 3 months but I find I don't struggle as much to stand up from a seated position. Medicare does cover the cost.