What is it?
A term, used in combat sport, to describe a limited ‘ability’ to absorb blows to the jaw or chin. It’s a significant disadvantage, but the likes of Amir Khan and Wladimir Klitschko have managed to become champions despite supposedly weak mandibles.
What’s behind it?
The New York State Athletic Commission, after examining dozens of boxers, found that while skull thickness was a sometime indicator of toughness, genes and their influence on punishment thresholds were at the root of the ‘glass jaw’.
Also known as
‘China chin’ (which references the delicate, translucent material) and ‘suspect jaw’. The converse – ‘iron chin’, ‘granite chin’ – is used for boxers such as Muhammad Ali and Evander Holyfield, who had a reputation for withstanding heavy punches.
Can it be fixed?
According to trainers, neck-strengthening exercises and learning to anticipate and roll with the punches, thereby reducing impact, help improve a fighter’s tolerance for punishment. But you don’t know if it’s fixed until you’re clocked in the jaw.