At the clicker drop almost all the arm and trunk muscles are more active than in the half second before, and they move together

The summary today

The question rests on a single, carefully made study, a master's thesis from the University of São Paulo. Ten recurve archers from the Brazilian national team, 72 arrows each at 70 metres, electromyography on twelve arm and trunk muscles: eleven muscles out of twelve are more active in the 50 milliseconds around the clicker drop than in any window up to half a second before, and pairs of muscles move almost in unison, with correlation coefficients between 0.72 and 0.99, the great majority above 0.90. The picture is not entirely uniform, though. The study compares the clicker window only with the windows before it, and in the hundred milliseconds after the clicker drop the mean activity of the rectus abdominis, latissimus dorsi, upper trapezius and posterior deltoid is higher still: for these trunk muscles the peak may come just afterwards, although no test compares the two windows. The lumbar multifidus stays at 2 to 4 per cent of maximum contraction in every window before the clicker drop, without rising towards the release; the finger extensor is the muscle most independent of the others; and the serratus anterior muscles form a separate group from the rectus abdominis. A synergy analysis of twenty-eight archers, in 2021, reads the same movement differently, with different groups of muscles switching on in different phases, from the end of the draw to the follow-through. Nobody has repeated the measurement in another laboratory or checked whether in beginners the muscles rise at different times.

Also phrased as: "the whole body works together at the clicker"; "peak activation at the release"; "muscle synchrony in the shot"; "electromyography at the clicker drop"; "co-activation of arms and trunk"

Evidence

• 2018
  For Archers Published later

  10 recurve archers from the Brazilian national team, 72 arrows at 70 m (12 ends of 6), surface electromyography on 12 arm and trunk muscles in 100 ms windows around the clicker drop. Eleven muscles out of twelve are more active between -50 and +50 ms from the clicker than in the windows back to -500 ms (F from 8.4 to 111.9, all p < 0.001); the exception is the lumbar multifidus, flat in those windows between 2.27 and 3.65 per cent of maximum contraction (F(4,3199) = 0.69, p = 0.59). The windows after the clicker drop are analysed separately: between 50 and 150 ms after the clicker the mean is higher than around the clicker in the rectus abdominis (28.77 against 18.75), latissimus dorsi (14.76 against 10.31), upper trapezius (39.66 against 35.21) and posterior deltoid (32.83 against 25.89), with very wide standard deviations and no test between the two windows. Cross-correlations between pairs of muscles range from 0.72 to 0.99, the great majority above 0.90: triceps, pectoralis major and posterior deltoid are coupled to all the postural muscles (0.91 to 0.99), while the finger extensor is the most independent (0.72 with the rectus abdominis, 0.76 with the finger flexor and multifidus) and the rectus abdominis correlates only weakly with the serratus anterior muscles (0.87 and 0.89). Master's thesis, not published in a journal.

  Temporal pattern in the muscles of the upper limbs and the trunk in the archery · Nadjila Tejo Machado

• 2020
  Context Archers Published later

  A world champion horseback archer using the Khatrah technique, muscle forces estimated from electromyography over the best 5 of 10 shots: on the bow side at full draw, pectoralis major 171 N, latissimus dorsi 118 N, middle trapezius 218 N; the trunk muscle average goes from 35 N in the starting stance to 169 at full draw and 76.7 at the end of the shot. A single case, a different style, no clicker, in a journal with questionable editorial standards.

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

• 2021
  Context Archers Published later

  28 recurve archers of three levels, electromyography of 13 muscles over 12 shot cycles at 30 m, synergies extracted with non-negative matrix factorisation: the end-of-draw synergy combines triceps and anterior deltoid of the bow arm with middle trapezius; the aiming synergy the bow-arm elbow extensors with middle and posterior deltoid and triceps of the drawing arm; the follow-through synergy biceps and finger extensor of the drawing arm with biceps, anterior deltoid and latissimus dorsi on the bow side. It describes how muscles group by phase, not when each one peaks.

  Muscle coordination during archery shooting: A comparison of archers with different skill levels · Zhang Baifa, Zhou Xinglong, Luo Dongmei

Status history

1. 2018 Reported The first study to time twelve arm and trunk muscles together, on ten Brazilian national team archers and seventy-two arrows each at seventy metres, finds eleven muscles out of twelve more active in the fifty milliseconds around the clicker than in the preceding half second, with synchrony coefficients between pairs of muscles almost always above 0.90. The exceptions are the lumbar multifidus, which does not change in the windows before the clicker drop, and the serratus anterior, which forms a separate group from the other postural muscles; on top of that, for several trunk muscles the mean over the following hundred milliseconds is higher still. A single study, of ten people: there is evidence in favour and it is limited.
2. 2020 Reported A single case of horseback archery, in a journal with questionable editorial standards, estimates the forces of the trunk muscles on the bow side with electromyography: they load up together to full draw, at about 169 newtons on average, and unload together after the release. It is a different style, a single archer, and there is no clicker to time from: the status does not move.
3. 2021 Reported A muscle synergy analysis of twenty-eight recurve archers of three levels, thirteen muscles and twelve shots at 30 metres, splits the movement into three groups of muscles that switch on in different phases: one at the end of the draw, one while aiming, one in the follow-through, each with different muscles. It does not contradict the shared rise around the clicker, since it measures how the muscles group together rather than how active each one is at that moment, but it is a reminder that saying all together simplifies. There is still a single supporting study, and the status does not change.

Related

Related articles

• Which muscles work in an archery shot, and at what share of their maximumWhich muscles switch on in an archery shot, in which phase and at what share of their maximum, and why studies give different figures for the same muscle.
• The final pull: what happens in the last millimetres before the clickerHow many millimetres and seconds the final pull takes, how it differs between better and worse arrows, and what the aim and the muscles do as the clicker drops.
• Muscle synergies in archery: the motor patterns of elite archersMuscle synergies in archery: what changes between elite and novice archers, and what happens on the best arrows, at the clicker and at the release.

Research lines

• 46 studiesShooting EMG from 1971 to today
• 54 studiesMovement variability and individual technique since 1971

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