1. An athletic performance monitoring device comprising: an accelerometer adapted to be worn by an athlete close to the center of gravity of the athlete; and a user-worn device with a processing system integral thereto such that the processing system can be worn by the athlete; wherein the accelerometer is further configured such that it can wirelessly communicate acceleration data, relating to the acceleration of the athlete, to the processing system, and wherein the processing system is configured such that, during use, it requests acceleration data from the accelerometer only when a predefined event has occurred, and such that it can process the acceleration data it receives from the accelerometer to provide athletic performance information.