Usually, the oil used by bodybuilding athletes is tanning oil, which has a certain heat preservation effect. The main purpose of tanning is to highlight muscle lines and create appropriate shadow effect, but of course it can't achieve the effect of cosmetic surgery. This can better help the referee to judge the technical indicators such as muscle line, proportion and latitude. There are also quite a few bodybuilders or bodybuilders who specialize in taking photos and tanning with ultraviolet rays.