If you can bend over for a long time and increase your weight, it will help to increase the latitude and strength of your arm. However, the efficiency of this kind of exercise will be very low (it will take a long time to be effective), and because of the single movement and no lines on the arms, fitness pays attention to maximizing the training effect in the shortest time. For boys, the latitude of the arm is a strong embodiment, and the lines on the arm are an important embodiment to distinguish your sports level, especially when wearing short sleeves. And in my opinion, the boy's arm circumference of 40 is a dividing line, and more than 40 will give people a clear sense of strength visually. So boys need to pay attention to the establishment of arm latitude (horizontal and vertical) and lines. The following two muscles are developed by arm training.
Biceps brachii, starting point: the long head starts from the supraglenoid tubercle of the long tendon and the short head starts from the coracoid process of the scapula. Stop point: the tendon stops at the trochanter of radius, and the aponeurosis stops at the fascia of forearm.
Triceps brachii, starting point: the long head starts from the subscapular tubercle, the lateral head starts from the outer upper part of the radial nerve groove behind the humerus, and the medial head starts from the inner lower part of the radial nerve groove. Stop point: olecranon.