Cupping is a traditional medical technique that many cultures have accepted as part of their healing modalities. In Chinese Medicine, we use cupping for internal medicine as well as muscular therapy. Cupping is a great way to reduce tight muscles without having to deal with the pro-long soreness of deep tissue.
In my experience,cupping is more effective for people that have systemic tightness in muscles groups. Many athletes enjoy the benefits from cupping. However, cupping can leave marks over the area that was treated. Some people get scared when they see the marks. I often describe them as having the appearance of having a fight with a large octopus. The marks are not permanent and usually go away within a week or two. Some people will not have any marks left after the session.
Here is another clip from Michael Phelps, and yes, it makes me cry with that sound track. There is a short section where you see Michael Phelps receiving Fire Cupping, a very traditional way of using the cups.