I’m a pretty serious runner and I credit the slant board for not just with preventing Achilles and plantar fascia problems, but also with improving my ankle flexibility and range of motion. This is a great exercise item to have around the office to just step on to stretch or to use for more difficult calf raises. I now use it for weighted calf raises in my home gym and it is completely sturdy. Even the fittest athlete will have sore calves after using this board for the first time.