The drawing arm's tremor comes from the upper arm rather than the shoulder blade, and muscle activity explains only part of it

The summary today

The answer comes from a single laboratory study of 10 male beginners holding a 26-pound bow in six simulated positions, with motion sensors on the upper arm and the shoulder blade and electromyography of eight muscles. Tremor power is greater at the upper arm in both frequency bands measured, 8 to 12 hertz and 3 to 7. The link with muscle activity is weak and changes sign: at partial draw more activity goes with less tremor, at full draw partly with more, and the strongest correlation (r = -0.569) explains about a third of the variation. The authors infer two mechanisms, a neural one for the fast tremor, which does not follow contraction, and a reflex one for the slow tremor, which does. As early as 1993 a measurement of the draw hand's movement had separated the 8 to 12 hertz tremor from a slower oscillation that fatigue does not change. What is missing is expert archers, arrows actually shot and a link with where they land.

Also phrased as: "tremor at full draw"; "drawing arm shaking"; "shoulder tremor"; "shaking at anchor"; "where the tremor comes from"

Evidence

• 1993
  Context Archers Published later

  7 male university-level archers, draw-hand movement measured together with electromyography while they held the draw until fatigue, for 52 seconds on average: besides the tremor peak at 8 to 12 hertz, closely coherent with the muscle signal (coherence 0.81 to 0.96), there is a slower oscillation, below 5 hertz, that sustained effort does not change and that the authors link to movement control. It does not distinguish between upper arm and shoulder blade.

  Biomechanical Study of the Final Push-Pull in Archery · P. Leroyer, J. Van Hoecke, J.N. Helal

• 2010
  For Archers Published later

  10 male beginners with a 26-pound recurve bow, six simulated positions (arm at 90, 100 and 110 degrees of elevation, at partial and full draw), motion sensors on the upper arm and shoulder blade of the drawing arm and electromyography of eight muscles: tremor power is greater at the upper arm both at 8 to 12 hertz (F(1,28) = 8.96, p = 0.01) and at 3 to 7 hertz (F(1,28) = 40.5, p < 0.0005).

  Activation and tremor of the shoulder muscles to the demands of an archery task · Jiu-Jenq Lin, Cheng-Ju Hung, Ching-Chieh Yang, Hsing-Yu Chen, Feng-Ching Chou, Tung-Wu Lu

• 2010
  For Archers Published later

  In the same study the strongest correlation between shoulder muscle activity and tremor (r = -0.569) explains 33 per cent of the variation, as the authors themselves note among the limitations: how hard the muscles work says little about how much the arm shakes.

  Activation and tremor of the shoulder muscles to the demands of an archery task · Jiu-Jenq Lin, Cheng-Ju Hung, Ching-Chieh Yang, Hsing-Yu Chen, Feng-Ching Chou, Tung-Wu Lu

• 2010
  Context Archers Published later

  The link changes sign with the draw: at partial draw the coefficients between electromyography and tremor range from -0.22 to -0.57, while at full draw positive correlations with the slow tremor appear (up to 0.573). The 8 to 12 hertz tremor does not follow contraction (coefficients between -0.310 and 0.492), the 3 to 7 hertz tremor does, and the authors attribute the first to central neural modulation and the second to the mechanical reflex.

  Activation and tremor of the shoulder muscles to the demands of an archery task · Jiu-Jenq Lin, Cheng-Ju Hung, Ching-Chieh Yang, Hsing-Yu Chen, Feng-Ching Chou, Tung-Wu Lu

Status history

1. 1990 Not studied In the registry's bibliography nobody has yet measured the drawing arm's tremor: neither where it comes from nor how much it depends on muscle work.
2. 1993 Not studied The first measurement of draw-hand tremor arrives, on seven university archers holding the draw until fatigue: alongside the 8 to 12 hertz tremor, which closely follows the muscle signal, there is a slower oscillation that sustained effort does not change. The study does not distinguish between upper arm and shoulder blade, so the question remains unanswered.
3. 2010 Reported The first study to ask the question, on 10 beginners in the laboratory with sensors on the upper arm and shoulder blade, finds stronger tremor at the upper arm in both bands, and a weak link with muscle activity that changes sign with the draw and at best explains a third of the variation. It is a single small study, of beginners and with no arrows shot: reported.

Related

Related articles

• The string elbow: where it sits and what changes when it risesWhere the string elbow sits in strong archers, whether aligning it with the line of force earns more points, and what changes when it rises.
• Bow arm tremor in archery: why it happens and how to reduce itBow arm shake at full draw is two movements, a slow sway and a fast tremor. What the studies measure, where the tremor comes from and how to reduce it.

Research lines

• 27 studiesTremor and sway while aiming: telling two phenomena apart since 1990
• 21 studiesFatigue, arrow volume and recovery: the dated trail

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