CrossFit is a fitness regimen developed by Greg Glassman over several decades. Glassman, CrossFit's Founder and CEO, was the first person in history to define fitness in a meaningful, measurable way: increased work capacity across broad time and modal domains. He then created a program specifically designed to improve fitness and health.

CrossFit is constantly varied functional movements performed at high intensity. All CrossFit workouts are based on functional movements, and these movements reflect the best aspects of gymnastics, weightlifting, running, rowing and more. These are the core movements of life. They move the largest loads the longest distances, so they are ideal for maximizing the amount of work done in the shortest time. Intensity is essential for results and is measurable as work divided by time—or power. The more work you do in less time, or the higher the power output, the more intense the effort. By employing a constantly varied approach to training, functional movements and intensity lead to dramatic gains in fitness.