There are thousands of cross trainers claiming all sorts of things, but they all have one common flaw: They are based on 50:50 swing/stance timing. They are neither like walking nor running. The patented Bionic Runner mechanism has a timing and motion based precisely on running. It uses a unique 60:40 swing/ stance phase timing to maintain your running fitness, without the impact. This sets the Bionic Runner apart from old school cross trainers and ellipticals. It specifically recruits and stresses the same muscles as running, improving running-specific fitness and stride economy.