In the basic principles of CrossFit^®, the goal is to improve fitness, related to the simultaneous development of strength and endurance. This is also the main idea of concurrent training, which has been researched since the 1980s. This article aimed to analyze the acute and chronic effects of CrossFit^® and to assess the relevance of using the concurrent training methodology. The findings show that CrossFit^® is an intense form of exercise that affects the function of the endocrine, immune, and central nervous systems. It also has potential in the development of strength and endurance parameters. These conclusions were compared with relevant concurrent training studies. Although the CrossFit^® interventions (workouts of the day) have much in common with concurrent training, methodological recommendations can only be partially transferred. The approach for training and athlete development must be based on the originality of this sport.