Muay Thai or literally Thai boxing is a combat sport of Thailand that uses stand-up striking along with various clinching techniques. This discipline is known as the "art of eight limbs" as it is characterized by the combined use of fists, elbows, knees, and shins.
Like most full contact fighting sports, Muay Thai has a heavy focus on body conditioning. Muay Thai is specifically designed to promote the level of fitness and toughness required for ring competition. Training regimens include many staples of combat sport conditioning such as running, shadowboxing, rope jumping, body weight resistance exercises, medicine ball exercises, abdominal exercises, and in some cases weight training. Thai boxers rely heavily on kicks utilizing the shin bone. As such, practitioners of Muay Thai will repeatedly hit a dense heavy bag with their shins, conditioning it, hardening the bone through a process called cortical remodeling. Striking a sand-filled bag will also have the same effect.