Wrist in Mameluke thumb draw archery: Ariffin 2018

A single archer, winner of the World Horseback Archery Championship in Korea in 2014, shot five arrows with a 45-pound traditional bow using the Mameluke technique, drawing with the thumb and finishing with the movement called khatrah: at the release the bow wrist deviates towards the little finger and the hand pushes forward, rotating the bow. Using electromyography of three wrist muscles in each arm (flexor carpi radialis, extensor carpi ulnaris, extensor digitorum communis), the authors estimated each muscle's force across six phases of the shot.

Flexor carpi radialis carried the most load in both arms. In the draw arm it reached 136 N at full draw and stayed at about 132 N at the release, with extensor carpi ulnaris at 60 N and the finger extensor at 21 N. In the bow arm the values rose phase by phase: flexor carpi radialis went from 159 N at full draw to 176 N at the release, and at the release extensor carpi ulnaris produced about twice the force of the finger extensor, 88 against 50 N, whereas at full draw the two were similar (44 and 46 N). The authors link this doubling to the ulnar deviation of the wrist that khatrah requires.

The archer, 75 kg and 170 cm, stretched and then performed maximum voluntary contraction tests for each muscle, in flexion and extension. The shot was divided into six phases: stance, nocking, pre-draw, full draw, release and follow-through; how the phases were identified is not described. The signal was band-pass filtered with a Butterworth filter, rectified, low-pass filtered and normalised to the maximum contraction; the five trials were aligned with a functional data analysis technique and then averaged.

Each muscle's force was estimated by multiplying the normalised activation by a theoretical maximum force, the physiological cross-sectional area times a specific tension taken from the literature: 1.6 cm² and 100 N/cm² for flexor carpi radialis, 2.1 and 0.8 cm² with 62 N/cm² for the two extensors. The same shots are also analysed in a second paper by the same authors on the upper limb.

One archer and five arrows describe that archer's shot, not the Mameluke technique in general. The forces are not measured: they are electrical activations converted into newtons using muscle cross-sections and tensions from tables, not from the person, and if those constants change every number changes. Some values exceed the theoretical maximum the method itself allows (flexor carpi radialis in the bow arm reaches 176 N against a maximum of 160, the finger extensor 50 against a maximum of about 50): the reference contraction probably fell short of the real maximum.

Sampling rate, electrode placement, filter frequencies and the criterion for separating the phases are not reported. The paper does not say whether the shots were taken on foot or on horseback, and arrow speed, which the authors say khatrah greatly increases, was not measured. The conclusion that these values can serve as a benchmark for reducing injury risk has no injury data behind it.

For archers using a Mediterranean draw and an Olympic recurve the transfer is limited: a thumb draw and actively rotating the bow at the release are different actions. For those who shoot historical bows or practise horseback archery with a thumb draw, the paper gives a qualitative picture: in the bow arm the wrist muscles work harder and harder up to the release, and at the release, with the ulnar deviation of khatrah, extensor carpi ulnaris is the one of the three measured muscles that rises most. It describes a single champion, useful for seeing where the wrist's work is concentrated, not a value to aim for or a safety threshold.