https://matteocampagna.com/en/registry/technique/thumb-release-bow-arm Changes to this claim in Matteo Campagna's evidence registry: its status, its year-by-year history, revisions of the page. en-gb https://matteocampagna.com/en/registry/technique/thumb-release-bow-armEverything we know comes from a single archer: a horseback archery world champion with a 45-pound traditional bow and the khatrah release of the Mameluke technique, the one in which the string is held by the thumb. In 2018, electromyography of three muscles per wrist, turned into forces using muscle cross-sections taken from the literature, gives 176 newtons at release for the flexor carpi radialis of the bow arm against 132 on the string arm, and the same order for the extensor carpi ulnaris and the finger extensor; between full draw and release the flexor carpi radialis keeps rising only on the bow side. The detail most consistent with the technique is the extensor carpi ulnaris of the bow arm, which at release works almost twice as hard as the finger extensor and peaks in the follow-through, as one would expect from a wrist that deviates towards the ulnar side. In 2020 the same data, extended to ten muscles and published in a venue with questionable editorial standards, complete the picture: the arm and forearm work harder on the bow side, but the trunk works harder on the drawing side. Before 2018 there is only a 1971 finding on kyudo, where the string is also held by the thumb: it says which muscles fix the two wrists, not how hard one side works compared with the other. One person, forces estimated rather than measured, and no comparison with a three-finger release: it is not known whether the difference comes from the thumb or from the bow.claim:rilascio-pollice-polso-arco:revision:2026-08-22:3Sat, 22 Aug 2026 08:00:00 GMT https://matteocampagna.com/en/registry/technique/thumb-release-bow-arm#storiaThe first finding on a shot with the string held by the thumb comes from kyudo: in three archers electromyography shows that the wrist of the bow arm is fixed by the extensor carpi ulnaris and that of the string arm by the flexor carpi radialis, meaning that the two wrists have different jobs. How hard each side works compared with the other, however, is not measured: the question has not yet been asked.claim:rilascio-pollice-polso-arco:history_entry:2026-07-29:1971Wed, 29 Jul 2026 08:00:00 GMT https://matteocampagna.com/en/registry/technique/thumb-release-bow-armclaim:rilascio-pollice-polso-arco:new_claim:2026-05-11:riportatoMon, 11 May 2026 08:00:00 GMT