AirLegs is a robotic exoskeleton which senses its users activity and makes them better, faster, stronger runners.  It relies on compressed air and can help its user run greater distances at higher speeds with less effort. This device was tested at the Army Research Laboratories in demonstrated a 10% reduction in metabolic cost (compared to no device) for users running at high speeds. It is the only device known to the US Army to officially augment the human running gait cycle.