Falls are dangerous for anyone, but they can be particularly worrying for senior citizens whose bodies aren't as resilient as they used to be. University of Missouri scientists may have a way to prevent those slips. They've developed a sensor system that measure changes in your gait speed and stride length to predict likely falls up to 3 weeks before they happen. If you slow down or shorten your stride in a significant way, it can alert health care workers (complete with imagery) so that they can take action before there's an injury.