With a thumb release the bow arm works harder than the string arm

The summary today

Everything 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.

Also phrased as: "thumb draw"; "mongolian release"; "khatrah release"; "bow wrist in traditional archery"; "horseback archery"

Evidence

• 1971
  Context Kyudo archers Published later

  3 kyudo archers (fourth dan, second dan, beginner), a discipline in which the string is held by the thumb inside the glove, surface electromyography on 14 muscles: over the first half of the opening the wrist of the bow arm is fixed by the extensor carpi ulnaris and that of the string arm by the flexor carpi radialis, and the authors read the extensor's burst as the fixation needed to hold the aim and push harder (English abstract p. 39, results p. 40). It says which muscles hold the two wrists, not how hard one side works compared with the other: the amplitudes are not normalised and there is no comparison between sides.

  An Electromyographic Analysis of Japanese Archery · Sadatsugu Kamei, Hideji Matsui, Mitsumasa Miyashita

• 2018
  For Archers Published later

  1 horseback archery world champion, 45-pound traditional bow, khatrah thumb release, average of 5 shots: at release the flexor carpi radialis produces 176 newtons on the bow arm against 132 on the string arm, the extensor carpi ulnaris 88 against 60, the finger extensor 50 against 21. The forces are derived from normalised electromyography multiplied by muscle cross-sections and stresses taken from the literature.

  Wrist muscle activity of khatrah approach in Mameluke technique using traditional bow archery · Muhammad Shahimi Ariffin, Azmin Sham Rambely, Noratiqah Mohd Ariff

• 2018
  For Archers Published later

  In the same archer the force of the flexor carpi radialis grows phase by phase from the starting position to full draw, from 19 to 136 newtons on the string arm and from 29 to 159 on the bow arm, but between full draw and release the flexor carpi radialis of the string arm stops, from 136 to 132 newtons, while that of the bow arm keeps rising, from 159 to 176.

  Wrist muscle activity of khatrah approach in Mameluke technique using traditional bow archery · Muhammad Shahimi Ariffin, Azmin Sham Rambely, Noratiqah Mohd Ariff

• 2018
  Context Archers Published later

  On the bow arm the extensor carpi ulnaris and the finger extensor are level at full draw (44 and 46 newtons), then at release the former reaches almost twice the latter (88 against 50) and in the follow-through rises further to 112, while the flexor carpi radialis drops to 133. The authors link this to the ulnar deviation of the wrist that the technique requires.

  Wrist muscle activity of khatrah approach in Mameluke technique using traditional bow archery · Muhammad Shahimi Ariffin, Azmin Sham Rambely, Noratiqah Mohd Ariff

• 2018
  Context Archers Published later

  On the string arm too the extensor carpi ulnaris works harder than the finger extensor in every final phase: 48 against 20 newtons at full draw, 60 against 21 at release, 60 against 22 in the follow-through.

  Wrist muscle activity of khatrah approach in Mameluke technique using traditional bow archery · Muhammad Shahimi Ariffin, Azmin Sham Rambely, Noratiqah Mohd Ariff

• 2018
  Context Archers Published later

  The tables also report an "MVC (%)" column, higher on the string arm (81, 86 and 89 for the flexor carpi radialis, extensor carpi ulnaris and finger extensor) than on the bow arm (77, 59 and 83), which the paper does not explain. It cannot be the relative activation during the shot: according to the method, the forces are the electromyography divided by each muscle's maximal contraction and multiplied by the same maximum force on both sides, so the comparison between forces is already the comparison between relative activations, and it points the way the claim does. What that column measures remains unknown.

  Wrist muscle activity of khatrah approach in Mameluke technique using traditional bow archery · Muhammad Shahimi Ariffin, Azmin Sham Rambely, Noratiqah Mohd Ariff

• 2020
  For Archers Published later

  The same archer across ten muscles, the best five shots out of ten: over the six phases of the shot the arm produces 102 to 341 newtons on the bow side against 133-176 on the drawing side, the forearm 18 to 105 against 20-71, while the trunk works harder on the drawing side, 105-178 newtons against 35-169. Same data as in 2018, in a venue with questionable editorial standards.

  Upper Extremity Muscle Force for Traditional Archery using Khatrah Technique Questionable venue · Muhammad Shahimi Ariffin

• 2020
  Context Archers Published later

  The middle deltoid of the bow arm is the most heavily loaded of the ten muscles measured: 31 newtons in the starting position, 132 at nocking, 527 in the pre-draw, 759 at full draw, 800 at release and 734 at the end of the movement.

  Upper Extremity Muscle Force for Traditional Archery using Khatrah Technique Questionable venue · Muhammad Shahimi Ariffin

• 2020
  Context Archers Published later

  The biceps of the bow arm works mostly before the draw and halves once the bow is drawn: 188 newtons in the starting position, 189 at nocking, 87 in the pre-draw, 91 at full draw, then 127 at release and 160 at the end of the movement.

  Upper Extremity Muscle Force for Traditional Archery using Khatrah Technique Questionable venue · Muhammad Shahimi Ariffin

Status history

1. 1971 Not studied The 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.
2. 2018 Reported A horseback archery world champion, with a 45-pound traditional bow and a khatrah release, is measured on three muscles per wrist over five shots. At release the flexor carpi radialis produces 176 newtons on the bow arm against 132 on the string arm, the extensor carpi ulnaris 88 against 60, the finger extensor 50 against 21, and between full draw and release the flexor carpi radialis keeps growing only on the bow side. The forces are estimated from electromyography using cross-sections from the literature, and there is one archer: reported.
3. 2020 Reported The same archer is described across ten muscles of the upper limb and trunk, and the division of the load can be read in full: the arm and forearm work harder on the bow side, with the middle deltoid of the bow arm the most heavily loaded muscle of all, reaching 800 newtons at release, while the trunk works harder on the drawing side. It is a more nuanced picture than the claim, but these are the same data as in 2018, in a venue with questionable editorial standards: they count once and the status does not move.

Related

Related articles

• The string grip: what changes between two fingers, three fingers and the thumbTwo fingers, three fingers or the thumb on the string: what studies have measured on grouping, steadiness, muscles and release, and where the data stop.

Research lines

• 46 studiesShooting EMG from 1971 to today
• 9 studiesThe string grip: fingers, thumb and thirty years of comparisons

Other claims in this domain

• CorroboratedBetween one and a half and two tenths of a second pass between the clicker sounding and the arrow leaving7 studies · 94 archers measuredStatus since 1990
• ReportedA camera diagonally behind the archer measures the vertical sway of the aim well, but not the horizontal1 study · 3 archers measuredStatus since 2010
• ReportedA continuous final pull through the clicker leads to better shots9 studies · 56 archers measuredStatus since 1993
• ReportedA sound or light cue about the angle of the bow arm tightens beginners' groups2 studies · 1 archers measuredStatus since 2012
• ReportedA thumb grip on the string is less tiring than a finger grip3 studies · 9 archers measuredStatus since 1990

See all claims on technique and biomechanics