This study intends to present the content of the workouts for developing the main muscle groups in the fitness for the masses. The study was conducted in the „Maxim Gym” Fitness Center of Bucharest during a period of 6 months (January – June 2016), with a subject of 30 years old. The same workout program was used throughout the entire period of the study, by means of progressive overload and sets and by alternating the exercises for specific muscular zones. The results of the study reveal the decrease of the body weight, the increase of the thoracic perimeter and the diminution of the waist during breathing-in and breathing-out as well. These changes are due not only to the efficiency of the training programs used but also to the observance of an optimal diet every day. The analysis of the fitness tests highlighted an improvement of the development of the main muscular groups thanks to the increase of effort overload and to the number of reps maintained at the required parameters. Following up this study, we are able to confirm that the training continuity is ensured and the physical fitness is improved if an optimal relation between the muscle groups is reached during a training micro-cycle. The use of the sets with progressive increase and decrease of the overload, on various strength apparatus for the development of each muscle group, helps to enhance the specific strength and muscle power on each apparatus.