Rash Guards are a great way to save your skin from Gi burn when training hard. They prevent the constant rub against the elbows, around the shoulders as well as help reduce skin pinch by acting as a second layer on your skin. Other benefits can include skin compression which helps minimise muscle vibration while under stress and allow blood to circulate more freely.
Rash Guards come in many colours and designs. You can wear any of these colours and designs for training but only your rank or permissible colours for competition. Judo has a strict code allowing only white for females during competition while BJJ only allows colours of your Rank Grade.