Mermaid line is not a unique physiological phenomenon of men, and girls can also form beautiful mermaid line through fitness. The proper name of mermaid line is "external oblique muscle of abdomen", which refers to two lines that form a V shape on both sides of male abdomen near the top of pelvis. Because its shape is very similar to the slightly contracted shape of the lower part of the fish, it is called a fishing line. But mermaid line is not a unique physiological phenomenon of men, and girls can also form beautiful mermaid line through fitness. The mermaid line of girls refers to the lines of abdominal muscles on both sides of the waist, which can show the beauty of girls' body curves. Girls with mermaid lines often make people lament their perseverance in fitness and exercise, and show confidence in their health and appearance. Mermaid line not only makes the waist stronger, but also makes the abdominal lines longer and makes the overall image of girls more exquisite. The vest line refers to the clear, flat and fashionable abdominal muscles of girls, showing a masculine aesthetic feeling. Girls with vest lines usually go through high-intensity exercise and strict diet control. This line shows the strength and firmness of abdominal muscles, which makes girls feel more athletic and confident.