1) Bodyweight exercise 2) Extension 3) Greater than normal extension 
[exercise] A hyperextension or back extension is an exercise that works the lower back as well as the mid and upper back, specifically the erector spinae. It may be performed using a Roman chair to hold the feet down and hips up or, without equipment, by lying face-down on the floor, and lifting the torso and arms together up off the floor....
Extreme extension of a limb or body part.
Extension of a limb or part beyond the normal limit. ... Synonym: overextension, superextension. ... (05 Mar 2000) ... 
(hi″pәr-әk-sten´shәn) extension of a limb or part beyond the normal limit.
Abnormal movement of a limb beyond its limit.
Type: Term Pronunciation: hī′pĕr-eks-ten′shŭn Definitions: 1. Extension of a limb or part beyond the normal limit. Synonyms: overextension, superextension
(hi;per-ek-sten;shun) Extension beyond the normal anatomical position or 180∞.
[n] - greater than normal extension
noun greater than normal extension
Extreme or excessive extension; greater than 180°
the extension of a part of the body beyond normal limits.
greater than normal extension