Forearm muscles at the release: Ertan 2003 study

Thirty people in three groups of ten, five men and five women in each, were recorded with electromyography while shooting: archers from the Turkish national team, beginners from a city archery club, and university students who had never shot. Two muscles were studied, the flexor digitorum superficialis and the extensor digitorum of the drawing forearm, and the signal was synchronised with the fall of the clicker by a switch mounted on the bow handle.

The central finding is that everyone, non-archers included, answers the fall of the clicker with an active contraction of the extensor and a gradual relaxation of the flexor. In this sample, then, the release is not a simple letting go of the fingers: the fingers also open through contraction of their extensors. The time at which the extensor reaches its peak changes with level: about 100 milliseconds after the clicker in the elite archers, 200 in the beginners and 300 in the non-archers. The difference between elite and non-archers in the normalised extensor value is significant at 300 milliseconds (p 0.010).

On the flexor, relaxation is faster in the elite archers than in the other two groups, and at 200 milliseconds the normalised activity separates elite from beginners (p 0.017) and beginners from non-archers (p 0.025). In all three groups extensor and flexor differ from each other across every interval after the clicker falls.

Before the clicker, elite archers and beginners show a stable balance between the two muscles; the non-archers instead arrive with the extensor already more active than the flexor in every interval, a preparation phase the archers do not have. One elite archer, a woman among the top ten in the world rankings, does the opposite of all the others: her extensor activity falls significantly 100 milliseconds after the clicker, and her flexor switches off faster too.

The elite archers were national team members, with FITA scores of 1,296 for the men and 1,322 for the women and eight and ten years of training; the beginners came from the city club, with scores of 1,157 and 1,147 and five and four years of practice; the non-archers were students with no experience at all. The mean ages differ between groups: 21.8 and 24.8 years in the elite group, 17.3 and 16.6 in the beginners, 28.2 and 24.4 in the non-archers.

The recordings were made in a laboratory, in a single session for each participant. Surface electrodes were placed on the central portion of the two muscles, located by palpation while the subject simulated the shooting position and contracted maximally; the skin was shaved, lightly abraded and cleaned with alcohol, the two electrodes about two centimetres apart and the reference on the olecranon of the drawing elbow.

A mechanical switch fixed to the bow handle marked the exact moment the clicker fell, and its signal was superimposed on the electromyographic trace. After three practice shots, each participant shot twelve arrows in succession, with sampling at 500 hertz triggered by hand shortly after full draw so that the release fell roughly halfway through the recorded period. Five seconds were recorded for each shot, two and a half before and two and a half after the clicker fell, and the analysis uses the two second window centred on the clicker.

The signal was rectified, averaged over 100 millisecond intervals and normalised against each muscle's maximal voluntary contraction, obtained by having the fingers contract in the three-finger hook against a stable resistance, as when holding the string. The means of the twelve shots were computed for each subject and then for each group. The comparison between the two muscles within each group is a paired-samples t-test, interval by interval; the comparison between groups is a one-way analysis of variance with Tukey tests.

The resolution of the analysis is 100 milliseconds, so the three values of 100, 200 and 300 milliseconds are one interval, two intervals and three intervals rather than measured times. Within that grid there is no distinguishing an archer who reacts to the clicker from an archer who anticipates it, and the paper reports no statistical test on the timings at all: the difference between groups is significant on the amplitude of the signal at 300 and at 200 milliseconds, not on the moment of the peak.

The moment the arrow leaves the string was not measured. The only time reference is the fall of the clicker, and the release is inferred from the shape of the muscle signal. On this the abstract contradicts itself: it states that everyone shows a gradual relaxation of the flexor and then concludes that a clear relaxation of the forearm flexors affecting the release movement was not observed.

The groups are not comparable on anything other than shooting. The mean ages run from sixteen to twenty-eight, the beginners are adolescents and the non-archers the oldest adults in the sample; the non-archers shot with a bow that was not theirs, whose draw weight and settings are not given, and met a clicker for the first time. Two muscles only, on one arm, in a single session, over twelve arrows in a laboratory.

No measure of accuracy accompanies the recordings: the FITA scores come from other occasions rather than from the arrows recorded, so the study does not link the muscle strategy to where the arrows went. The case of the world-class archer who does the opposite of all the others remains a single case, and the paper draws no consequences from it. In the earlier work the authors cite, some high-level archers used the flexor-relaxation-only strategy: seven of the fifteen archers in one of those studies instead used the extensor contraction seen in the subjects here.

This is the source the registry uses when the release is discussed as an active movement. The widespread teaching says the string should go through a simple relaxation of the fingers, since its tension is enough to open them; here, across thirty people at three different levels, the fingers open with a measurable contraction of their extensors, while the flexors switch off gradually. The authors do not put this forward as a technique to teach: they describe it as what they found in the signal.

The difference between levels lies in speed, not in strategy. In the national team archers the extensor peaks within the first 100 millisecond interval after the clicker, in the beginners within the second, in the non-archers within the third; and the flexor switches off earlier in the elite archers. The strategy itself is the same for everyone, including those who had never shot: it is not an ability that gets acquired, it is the way the hand opens.

The observation that stays most useful concerns the non-archers: they came to the clicker with the extensor already active, preparing for the release before the signal, and the archers had no such preparation phase. The opposite of what one might imagine: those who cannot shoot do not wait, they anticipate.

Two things this source does not say: it does not say that a release done one way or the other scores more points, because accuracy was not measured, and it does not say how much time actually passes between the clicker and the arrow leaving, because the analysis window is 100 milliseconds wide.