FLIGHT TIME

There is described a system for monitoring an athletic performance, comprising: one or more processors; memory storing computer executable instructions that, when executed by the one or more processors, cause the system to at least perform: receiving, from one or more foot sensor systems, launch input data relating to a plurality of foot launch events during a first time period; receiving, from the one or more foot sensor systems, strike input data relating to a plurality of foot strike events during the first time period; determining, by the one or more processors, a first flight time associated with a first set of timestamps of a plurality of timestamps associated with each foot launch event and foot strike event; and determining, based on the first flight time, an energy expenditure of a user during the first time period.