There are no mass and definition exercises
Especially with the general distinction between mass and definition exercises, it shows that some beginners and even advanced lifters do not understand the basic principles of strength training. According to common belief, it is the so-called mass exercises that bring “meat” on the ribs, while the definition exercises serve to bring shape this “meat” into an aesthetic physique. As already described above, you cannot shape a muscle, on the contrary, the muscle shape is always genetically predetermined.
The correct distinction would rather be that there are isolation and compound exercises. A typical isolation exercise (also called single-joint exercise) are e.g. leg extensions on a machine, while a multi-joint practice would be squats. In this case, the limiting point in an isolation exercise is the movement section in which the muscle must expend the most force in order to move the weight. To stay with the example of the leg extensions, here the limiting point is in the phase of the movement, in which the leg is perpendicular to the ground. Analogous, in the barbell curl, it would be the moment when the arm is bent 90 degrees. Of course there are also exercises on machines, e.g. pec deck or leg curls. By using an “Excenter”, an attempt is made to optimally adapt the force curve of an exercise to the different force ranges of a muscle.
The “dead spot” (= the limiting point in an exercise where the muscle must expend the most force) is eliminated in multi-joint exercises by distributing the load to other muscle groups, thereby helping to overcome this point in a combined effort. In the bench press these are above all triceps and shoulders. This makes it possible to use a much higher weight than in an isolation exercises, which in turn, makes the training effect greater for the target muscle. In the end, this results in a greater stimulus for muscle building, which is forced more strongly by multi-joint exercises than by isolation exercises
Therefore, in a training routine the focus should always be on the basic exercises, which are usually multi-joint exercises. These are then supplemented by isolation exercises, which make it possible to treat weak points in your physique by targeted isolation of a muscle.