Our "Amputee Running Series" aims to provide you with a practical guide to help you begin running with your prosthesis. This second installment will walk you through the kinds of running feet, which can hopefully help you narrow down your choice. For the basics of amputee running—how to prepare your body and prosthesis—check out Part 1.
Running feet types
Getting the right running foot that fits your needs, as well as the requirements of the sport, is important. But before we proceed, we'll answer the question on everyone's mind: Can you run with your everyday prosthesis? Yes, you can.
However, using a specialized running leg can make your performance significantly more efficient. It can also improve your running biomechanics.
There are several running feet available for different types of running, such as distance running and sprinting. So, it would help if you were clear on which category of running you want to do.
Running feet designed for sprinting are stiffer compared to long-distance running feet. The reason is to allow quicker energy return and propulsion.
Sprinting feet are manufactured in two categories: 100-200 meters and 400-800 meters. Össur has two sprinting feet available on the market—the Cheetah Xtreme and Cheetah Xtend. Its main competitor, Ottobock, also manufactures two—the Sprinter and the C-Sprint.
Long-distance running feet
Long-distance running feet are designed to run 3 miles (5 kilometers) or further. They feature a curve that looks more like a letter "C" than the "J" that is common in sprinting feet. Long-distance running feet will release energy over a slightly longer time span vs quick bursts from sprinting feet, a requirement with which the "C" design can facilitate.
Oscar Pistorious' "blades" were long-distance running feet designed and manufactured by Össur. The blades are called the Flex-Foot Cheetah. Typically, an Össur Cheetah foot is used when you don't have enough clearance under your socket to fit a Flex-Run with Nike Sole.
Limb length discrepancy
When your prosthetist aligns your running leg, he/she typically makes your prosthetic side 1-2 inches taller than your sound side. It may seem like an enormous leg length discrepancy. However, if your legs were made equal in length, your running leg would feel short when loaded during a run.
Prosthetic running feet provide a lot of energy through compression (storing) and release (energy return). So, when it's loaded while running, the prosthetic running foot can shorten up to 2 inches. Simply put, a prosthetic leg that is 2 inches too tall when standing or walking will feel just right when it's fully loaded during running.
A foot whip refers to the inward rotation of the foot when running. This issue is often caused by weak hip flexors and adductors, which can be strengthened through exercising and stretching these problem areas and ensuring proper alignment.
A foot whip is a normal movement that occurs in all runners. Prosthetically speaking, whips often occur with poor suspension, improper prosthetic knee rotation, as well as tight or weak hip flexors and adductors.If you are a runner, what running foot do you use? How is your experience with the prosthesis? Share your experiences with us in the comments section below.