When an archer reaches full draw, dozens of muscles are working together, from the fingers of the drawing hand to the deep abdominal muscles. One of the most studied ideas in motor control is that the nervous system does not regulate them one by one but in groups: combinations of muscles with fixed weightings that switch on following a shared time course. These are muscle synergies, and in archery they can be extracted from surface electromyography.
What an archer wants to know is what separates an elite archer's shot from that of someone who has been shooting for less time, and the measurements answer in two parts. The number of synergies is the same at every level, about three: what changes is when they switch on, above all in the follow-through, and how the work is shared between the fingers, the arms and the shoulder blades. Within an elite archer's shooting, the best arrows are not the ones on which the body is stillest, but the ones on which the joints compensate for each other more as the release approaches.
What muscle synergies are
A synergy, in this sense, has two components. The first is a group of muscles with their relative weightings, which stays the same throughout the movement: one muscle may count for a lot and another for little. The second is a curve over time, which says when that group switches on and how strongly. Combining the curves with the groups reconstructs the signal recorded from each muscle, and synergies are usually extracted with a statistical method, non-negative matrix factorisation, which looks for the smallest number of synergies that still gives a faithful reconstruction.
Two things need to be kept in mind before any result. Synergies are derived from the muscles the electrodes are placed on, so a study that measures the arms and shoulders says nothing about the trunk; and their number depends on the criterion used to decide that the reconstruction is good enough. That is why the most useful comparison is between archers of different levels measured in the same laboratory, with the same muscles and the same method.
The three synergies of the shot
A laboratory in Beijing made that comparison in twenty-eight recurve archers, eight at national level, twelve at intermediate level and eight novices, recording thirteen muscles of the arms, shoulders and back over twelve shots at 30 m. Three synergies emerged at all three levels, on average 2.9 in the elite archers, 2.6 in the intermediates and 2.9 in the novices, with no significant difference, and each one corresponds to a phase of the shot.
-
End of the draw
The first synergy combines the triceps and anterior deltoid of the bow arm with the middle trapezius, which draws the shoulder blade back: it is the group that holds the push of the bow while the string reaches full draw.
-
Aiming
The second brings together the elbow extensors of the bow arm with the middle deltoid, posterior deltoid and triceps of the drawing arm, the muscles that hold the anchor while the archer aims.
-
Follow-through
The third works after the release: the biceps and finger extensor of the drawing arm, together with the biceps, anterior deltoid and latissimus dorsi on the bow side. The authors assign it the job of carrying the release through, with the drawing hand continuing behind the head.
The skeleton of the shot is therefore the same for the elite archer and the novice. Within that skeleton, though, muscles, timing and angles vary from one archer to the next, so much so that in the registry the idea that elite archers share a single correct shooting technique is refuted.
The trunk was not measured in that study. The data on the abdominal muscles come from two other laboratories, and they agree with each other. In kyudo, across nine practitioners, the coordination module that works in the second half of the shot loads on the internal oblique and transversus abdominis in the four most experienced and on the external oblique in the other five; in twenty-eight Indian archers of three levels the transversus works at 22.9% of maximal contraction at anchor and 32.9% at release in the elite group, against 7.4% and 12.2% in the novices. The registry therefore reports that in more experienced archers the transversus abdominis plays a larger part in stabilising the trunk, with a caution that comes from eight French elite archers: in the follow-through of their arrows scoring 8 or less the transversus is more active, not less, than on the 9s and 10s, so a more active transversus is not enough on its own to make a better shot.
Around the clicker
Synergies describe how the muscles are grouped through the shot; how hard each one works at the most delicate instant is shown by a different measurement. A master's thesis from the University of São Paulo followed ten recurve archers from the Brazilian national team over 72 arrows at 70 m, with electromyography on twelve arm and trunk muscles. Eleven muscles out of twelve were more active in the window from 50 milliseconds before to 50 milliseconds after the clicker drop than in any window up to half a second earlier, and pairs of muscles rose almost in unison, with correlations between 0.72 and 0.99, nearly all above 0.90.
The picture does have exceptions, though. The lumbar multifidus stayed between 2% and 4% of maximal contraction in every window before the clicker drop, without rising; the finger extensor was the muscle most independent of the others; and in the rectus abdominis, latissimus dorsi, upper trapezius and posterior deltoid the mean was higher still between 50 and 150 milliseconds after the drop, so in these muscles the peak may come just afterwards, although the study does not compare the two windows with a test. For that reason, and because the measurement has not been repeated in another laboratory, the claim that at the clicker drop almost all the arm and trunk muscles are more active than in the half second before, and move together is reported. It does not conflict with the three synergies, because the two studies measure different things: one how the muscles are grouped in the phases of the shot, the other how hard each one works at that instant.
What changes from one level to the next
If the number of synergies does not change, the difference lies elsewhere, and the first place it shows is timing. In the Beijing study the centre of activation of the follow-through synergy fell at 91.4% of the shot cycle in the elite archers, 87.9% in the intermediates and 71.9% in the novices, so much earlier, and with an enormous spread: the standard deviation was 3.7 points in the elite group and 29.5 in the novices. The centre of the draw and aiming synergies, on the other hand, did not change significantly from one level to another, and nor did the duration of any of the three. In the novices the synergies also overlapped more often, and the busiest moment of the shot, for everyone, was the middle of the follow-through.
The same study also finds the make-up of the synergies changing. In the follow-through synergy the flexor digitorum superficialis of the drawing hand carried less weight in the elite archers than in the intermediates and novices, and in the aiming synergy the novices used the middle deltoid less. This points in the direction of a finding that recurs across laboratories, that expert archers hold the draw with the shoulder and back more than with the forearm: in thirty Japanese archers, in the second before the clicker drop, the lower trapezius worked at 54.0% of maximal contraction in the elite group against 39.4% in the pre-elite group and 34.0% in the novices, and the ratio of upper to lower trapezius fell from 2.33 to 1.23 going up the levels. The claim is reported, because these are comparisons between different groups measured once, and in twenty-seven Turkish archers it was the posterior deltoid and middle trapezius that separated the levels.
This is also where the idea comes from that elite archers activate their muscles less while aiming. In three samples from different laboratories, in 2014, 2018 and 2026, the muscles of the fingers, arms and trunk almost always work less in the elite archers: in the most recent, eight French elite archers and seven intermediates at 70 m, the elite archers show less activity in eleven of the twelve muscles that differ between the groups. In all three, however, part of the trapezius that holds the shoulder blade works harder in the elite archers, and the posterior deltoid goes one way in 2014 and the other in 2026. Stated for every muscle, the claim that while aiming, elite archers activate their muscles less than intermediate archers is contested; the reading that holds up best is that elite archers shift the work from the fingers and arms to the shoulder blades.
The last difference is consistency from one shot to the next, and it has the most data. As early as 1990, with electromyography, Olympic archers repeated the same muscle pattern on 92% of their shots, national-level archers on 41% and novices on none, and the registry reports that expert archers repeat the shot with less variability than novices. Among archers who are already expert, though, consistency of movement alone does not separate the arrows in the 10 from the rest, and to see why you have to look inside the shooting of a single archer.
What happens on the best arrows
The study that answers this question followed six elite archers from a national squad for ninety arrows each at 18 m, and looked at how the angles of the shoulders, elbows and wrists varied from one arrow to the next. The variation was there on every arrow. On the 9s and 10s, though, it combined so that the changes cancelled each other out, and the orientation of the arrow stayed the same: the index that measures this compensation was around 0.4 to 0.6 at the release, against 0.1 to 0.3 on the arrows scoring 6 to 8. The compensation was absent at the start of the aim and built up towards the release; on the worse arrows it was still present, only weaker.
The result changes how consistency should be read, because an elite archer's joints move even on good arrows, but in directions that do not shift the arrow. The registry reports that on better arrows the joints of the shot compensate for each other more, and goes no further because there is a single study, of six archers. Two other pieces of work point the same way while measuring different things. In eight Brazilian archers of national level, on the best arrow the movement of the body over the feet went together with that of the bow, with correlations of 0.83 towards the target and 0.80 vertically, while on the worst arrow the link was absent; in ten Turkish traditional archers the bow's jolts while aiming were explained only by the action of both hands together, and by neither hand alone, but score was not measured there.
For individual muscles, arrow by arrow, the data agree less. In the eight French high-level archers, over 549 arrows at 70 m, the posterior deltoid and middle trapezius of the drawing arm were more active while aiming on arrows scoring 8 or less than on the 10s. On the finger flexors of the drawing hand two laboratories reach opposite answers: in four Turkish elite women archers, at 18 m indoors, the flexor digitorum superficialis worked slightly less on the 10s, at 80.0% of maximal contraction against 85.6% on the 8s, while in the French archers at 70 m the finger flexor and extensor were more active on the 10s. That is why the claim that on the best arrows the finger flexors work less before the clicker drop is contested.
At the release
When the string goes, the balance between the push of the bow hand and the pull of the drawing hand breaks, and both arms move. Only one study has measured this, with an accelerometer on each arm of two Malaysian university recurve archers, eighteen arrows each at 70 m. At the release the two arms moved in opposite directions on all three axes, with one exception: the movement across the line of shot on arrows with a middling score. Vertically the bow arm dropped and the drawing hand rose by almost equal amounts, between 1.5 and 3 cm depending on the score band; along the line of shot the bow arm went forward much further than the drawing hand went back, 6.8 cm against 1.2 on low-scoring arrows and 9.2 against 1.6 on high-scoring ones.
The registry reports that at the release the two arms move apart in opposite directions. No measurement has shown, however, that the size of that movement tells you where the arrow goes. The authors see a link in the movement across the line of shot, larger in the bow arm on low-scoring arrows and in the drawing hand on high-scoring ones, but with two archers, standard deviations as large as the means and no statistical test, the data describe the shape of the movement and cannot carry a comparison between arrows.
The legs take part too, and before the release. Nine expert Korean archers and nine novices simulated the shot on a force plate: in the experts the load under the feet was already shifting before the release, in the opposite direction to the push coming from the bow, and five leg muscles out of eight peaked in the window before the release, while in the novices the work came afterwards. It is a single study, with no arrows and no score, and the registry reports that expert archers prepare their balance before the release, while novices correct it afterwards.
What this means for training
Guidance for training comes from two sources: what the measurements say about the differences between levels, and what training studies have found on score. The measurements yield only one point, and it is the one made by the authors of the Beijing study themselves: the clearest difference between novices and experts lies in the timing of the follow-through, so they suggest that coaches and archers work on the timing and coordination of that phase.
On strength, the data need careful reading. The only study to compare the options, in sixty Indian archers of national level over twelve weeks, saw the group that alternated gym work and bow-specific strength reach an adjusted mean of 590.7 points over 72 arrows, against 569.1 for gym work alone, 557.4 for bow work alone and 532.6 for the group that trained as usual. In the registry the claim that combining gym strength and bow-specific strength improves score more than either alone is reported, with a limit that matters: the groups were not randomised, and the combined group trained six times a week, more than any other.
Elastic band exercises that mimic the draw are the most common way of bringing gym work closer to the shot, and here too the picture is split. In 2026 the first randomised study to separate the bands from everything else, in twenty-four traditional archers over eight weeks, saw grip and strength rise more than in the control group, but not score, which improved equally in both groups, and the claim that elastic band exercises improve score is contested. Work on the lower trapezius follows the same pattern. The registry reports that lower trapezius exercises rebalance the work of the trapezius muscles, because in fourteen Taiwanese university archers twelve weeks halved the ratio of upper to lower trapezius on the drawing side, from 2.2 to 1.1; that scapular stabilisation exercises improve score, on the other hand, is contested, and in a randomised trial of thirty-one Korean elite archers the score did not move.
That leaves variety in practice. In motor learning it is a widespread idea that changing the conditions helps a movement hold up outside the situation in which it was learned, but in archers the two studies that compared alternating distances with a fixed distance reach opposite results: in the first the group that changed distance gained 27.3 points and the fixed group 15.5, in the second the fixed distance won, 24.7 against 14.5. The claim that training at varying distances raises score more than always shooting at the same one is contested. On attention, too, which many coaches advise directing outwards, archers have a single direct comparison, sixteen young elite archers with six arrows per condition at 70 m, and in that comparison looking at the sight rather than feeling one's own body did not change the score.
How fatigue changes coordination
Synergies are usually measured in rested archers, and what happens as a session goes on is shown by studies of individual muscles. Since 2024 three papers have followed the same twenty Polish club archers, and after a hundred arrows electromyography finds a shift rather than a breakdown: the infraspinatus of the drawing arm drops in amplitude and in frequency, the lower trapezius produces a lower peak, while the deltoids and upper trapezius work harder, which is how the body compensates. In the same sample, however, three portions of the trapezius and the middle deltoid do not show the frequency drop typical of fatigue, and in 2026 the tone, stiffness and elasticity of six muscles are the same before and after the hundred arrows, which for these archers are a normal session. That is why the claim that beyond 100 arrows per session the shoulder muscles become fatigued is contested.
When fatigue is present, the two studies that looked for it find it in the bow. In twelve Italian archers, after a protocol of holds at full draw, the lateral sway of the bow increased in all twelve, by 20% on average, while the centre of pressure under the feet did not move; in seven university archers holding the shooting position to exhaustion, the frequency drop in the posterior deltoid went together with a tremor that showed up in the movement of the bow limb. The registry reports that muscle fatigue increases bow sway while aiming, on the strength of two small studies without a control group.
What you can see without a laboratory
Synergies cannot be seen by eye, because they need electrodes and a statistical analysis. Some of what the measurements have found does leave traces that a camera can pick up, though.
The first is the follow-through. After the release the bow arm goes forward and down while the drawing hand goes back and up: this is the movement described by the accelerometer study. That in the best archers the shoulder muscles stay active after the release, while in novices the activity stops, has been seen for decades; that keeping them active in the follow-through goes with better arrows, on the other hand, is contested.
The second is consistency. Filming a series of arrows from the side and comparing the frames at the clicker drop shows how much the position of the bow arm changes from one shot to the next, and it is a useful check for someone who is learning, because it is between novices and experts that variability falls. For archers who are already expert it is less useful: the best arrows are not the ones with the least movement but the ones on which the joints compensate, and a video cannot tell a movement that shifts the arrow from one that is cancelled out by another.
The third is aiming sway, which increased with fatigue in both fatigue studies. A camera placed diagonally behind the archer reads the vertical movement of the sight well but not the horizontal one, because from behind a rotation of the bow and a sideways shift look alike: the claim that a camera behind the archer, placed diagonally, measures vertical aiming sway well, but not horizontal sway rests on three archers from the German national squad and is reported. With the camera always in the same place you can compare the first ends of a session with the last, bearing in mind that from there only vertical sway reads well, whereas in the twelve Italian archers it was lateral sway that increased with fatigue.