String grips and release in recurve: Simsek study

A single high-level recurve archer, with FITA scores above 1300, shot at 18 metres with three different string hooks: the usual three-finger hook and two two-finger variants that the paper calls upper and lower, without describing them in detail. During the shots the electrical activity of nine forearm and shoulder girdle muscles was recorded, together with body sway on a force plate.

With the three-finger hook the finger flexors stayed contracted before the clicker went off and relaxed gradually just afterwards, while the extensors contracted abruptly after the click, which the authors read as the fingers opening. With the upper two-finger hook the flexors contracted and released sharply just before the clicker; with the lower one they contracted beforehand and relaxed gradually afterwards. With both two-finger hooks the extensors came in before the click, and the anterior deltoid was almost silent before the click and then contracted gradually. Fore-and-aft sway rose sharply around the clicker with the two-finger hooks, while the three-finger hook gave the mean sway closest to zero. The authors conclude that the three-finger hook is the most suitable and that it makes the best use of the shoulder blade.

Surface EMG (a wireless Delsys Trigno system sampling at 2000 Hz) recorded the flexor digitorum superficialis and extensor digitorum, the anterior, middle and posterior deltoid, the upper, middle and lower trapezius and pectoralis major, with a maximal voluntary contraction recorded for each muscle before shooting. The clicker sent an electrical pulse logged alongside the muscle signals, and the analysis covers the 400 milliseconds before it and the 800 after. A Kistler force plate under the archer's feet, 18 metres from the target, recorded forces and centre-of-pressure movement at 2000 Hz, normalised to body weight; only shots that hit the target were used for sway. There was a single session of 6 shots in all, after a 15-minute warm-up.

Six shots in all for three hooks means, if they were shared out as seems to be the case, about two per hook, from one archer who in all likelihood normally uses only one of them: the less familiar hooks may look less stable simply because they are less practised. The text gives no statistics and no numerical values for muscle activity or sway, and no data on where the arrows landed. The sway results contradict each other: the highest sway is first credited to the upper two-finger hook and a few lines later to the lower one. The conclusion about the shoulder blade does not come from the data either, since scapular position was not measured.

For anyone shooting with a three-finger hook, the study fits earlier work on skilled recurve archers: at full draw the forearm flexors and extensors work together, and at the clicker the flexors let go while the extensors take over. On the comparison between hooks, though, it supports no conclusion: with one archer and roughly two shots per hook, it is more a feasibility test than a comparison. Anyone who uses a two-finger hook, or is thinking of trying one, will find no data here that counts against it.