What is 4 pack abs?

4 pack abs, also known as upper abs, are the top two sections of the rectus abdominis muscle. These muscles are located on the front of the abdomen and can be seen when there is a low level of body fat. Achieving 4 pack abs requires a combination of strength training exercises such as crunches and planks, as well as a healthy diet and regular cardiovascular exercise to reduce overall body fat. While having a 4 pack may be aesthetically pleasing, it does not necessarily indicate a person's overall fitness level or strength.