An athletic performance monitoring system, comprising: a global positioning satellite receiver for obtaining data relating to a series of time-stamped position points; a first athletic performance monitor for measuring physical data relating to an athlete's performance; a computing device programmed and adapted to generate calibration data for the first athletic performance monitor based on data obtained via the global positioning satellite receiver, wherein the calibration data includes a plurality of correction factors for a range of athlete speed and use conditions; and a computing device programmed and adapted to determine at least one of speed data or movement distance data for the athlete's performance, wherein the computing device for determining at least one of speed data or movement distance data uses a first correction factor relating to a first use condition for a first portion of a first athletic performance during which the first use condition applies, and a second correction factor relating to a second use condition for a second portion of the first athletic performance during which the second use condition applies, wherein: (a) the first use condition is a first wind speed condition and the second use condition is a second wind speed condition, and wherein the system further comprises a wind speed monitor for determining the use condition during the first athletic performance; or (b) the first use condition is a first wind direction condition and the second use condition is a second wind direction condition, and wherein the system further comprises a wind direction monitor for determining the use condition during the first athletic performance. a global positioning satellite receiver for obtaining data relating to a series of time-stamped position points; a first athletic performance monitor for measuring physical data relating to an athlete's performance; a computing device programmed and adapted to generate calibration data for the first athletic performance monitor based on data obtained via the global positioning satellite receiver, wherein the calibration data includes a plurality of correction factors for a range of athlete speed and use conditions; and a computing device programmed and adapted to determine at least one of speed data or movement distance data for the athlete's performance, wherein the computing device for determining at least one of speed data or movement distance data uses a first correction factor relating to a first use condition for a first portion of a first athletic performance during which the first use condition applies, and a second correction factor relating to a second use condition for a second portion of the first athletic performance during which the second use condition applies, wherein: (a) the first use condition is a first wind speed condition and the second use condition is a second wind speed condition, and wherein the system further comprises a wind speed monitor for determining the use condition during the first athletic performance; or (b) the first use condition is a first wind direction condition and the second use condition is a second wind direction condition, and wherein the system further comprises a wind direction monitor for determining the use condition during the first athletic performance. (a) the first use condition is a first wind speed condition and the second use condition is a second wind speed condition, and wherein the system further comprises a wind speed monitor for determining the use condition during the first athletic performance; or (b) the first use condition is a first wind direction condition and the second use condition is a second wind direction condition, and wherein the system further comprises a wind direction monitor for determining the use condition during the first athletic performance.