It is not clear that single and double joint training can not be distinguished, in fact, their training goals are not the same, and of course they are also compulsory!
In fitness movements, it can basically be divided into double joint and single joint training, double joint is also known as basic action, single joint is also known as isolated action. Then it is not difficult to know that the basic movements are compounds, while the isolated movements are the isolation of one muscle group.
The single-joint movement is mainly a training movement that exercises the lines and forms of muscle blocks. It is in a movement that only one joint is active, it is to concentrate the force of the local muscle group, and the muscle groups in other parts have little or no synergistic muscle group force, so that the stimulation of the local muscles can be concentrated and deepened, so the weight used is lighter.
In the single-joint movement, although the local muscle group is isolated for exertion, in the last few attempts, the local muscle group can no longer exert strength, resulting in synergistic force, in fitness training, it is called power training. For example, when standing barbell curls, the main thing is to concentrate on the contraction force of the biceps brachii to lift the barbell, and no borrowing force is allowed when using accurate technical movements. However, when lifting to the last 1 or 2 reps, it can no longer be done with the contraction of the biceps alone, allowing the barbell to be lifted with the help of the coordinated force of the back and legs.
Double joint movements, mainly training movements to develop muscle mass and strength. It refers to the simultaneous movement of two joints in a single movement, and when the local muscles are exercised, the active muscles and other synergistic muscle groups will be involved in exerting force at the same time, and the movement of these joints is similar to the lever movement of mechanical structure. As a result of the exertion of the synergistic muscles, the weight can be lifted heavier. For example, in the bench press, the main exercise is the pectoralis major muscle, because the joints of the shoulder and elbow produce a leverage ratio during the upward push. As a result, the anterior deltoid and triceps brachii also exert synergistic force.
It can be seen that these two types of training complement each other, and it is indispensable to build a good figure.