[from CrossFit.com]

CrossFit begins with a belief in fitness. The aim of CrossFit is to forge a broad, general, and inclusive fitness. We have sought to build a program that will best prepare trainees for any physical contingency—not only for the unknown, but for the unknowable. After looking at a broad range of sport and physical tasks collectively, we asked what physical skills and adaptations would most universally lend themselves to performance advantage. Capacity culled from the intersection of all sports demands would quite logically lend itself well to all sport. Hence, our specialty is not specializing.

CrossFit is an evidence-based fitness program. We believe that meaningful statements about safety, efficacy, and efficiency, the three most important and interdependent facets of any fitness program, can be supported only by measurable, observable, repeatable facts, i.e., data. The CrossFit methodology depends on full disclosure of methods, results, and criticisms, and CrossFit HQ has employed the Internet as the primary means to support these values. Our charter is open source, making co-developers out of participating coaches, athletes, and trainers through a spontaneous and collaborative online community. CrossFit is empirically driven, clinically tested, and community developed. 

We define fitness as increased work capacity across broad time and modal domains. Capacity is the ability to do real work, which is measurable using the basic terms of physics (mass, distance, and time). Life is unpredictable (much more so than sport) so real world fitness must be broad and not specialized, both in terms of duration and type of effort (time and modal domains). 

The magic is in the movements. All of CrossFit’s workouts are based on functional movements. These are the core movements of life, found everywhere, and built naturally into our DNA. They move the largest loads the longest distances so they are ideal for maximizing the amount of work done in the shortest time (intensity). By employing a constantly varied approach to training, these functional movements at maximum intensity (relative to the physical and psychological tolerances of the participant), lead to dramatic gains in fitness. Intensity is essential for results and is measurable as work/time. The more work you do in less time, the more intense the effort. 

In implementation, CrossFit is, quite simply, the “sport of fitness.” We’ve learned that harnessing the natural camaraderie, competition, and fun of sport or game yields an intensity that cannot be matched by other means. The late Col. Jeff Cooper observed that “the fear of sporting failure is worse than the fear of death.” It is our observation that men will die for points. Using whiteboards as scoreboards, keeping accurate scores and records, running a clock, and precisely defining the rules and standards for performance, we not only motivate unprecedented output but derive both relative and absolute metrics at every workout. This data has important value well beyond motivation.