This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

v. To extend a joint beyond its normal position in a way that stresses the ligaments, often causing injury

v. extend a joint beyond its normal range

"Do not hyperextend your elbow joint during the movement."

holdout    extend    stretch out    exsert    stretch forth   

hyperextension