Muscles and the release in archers: Martin 1990

Fifteen archers from the United States team, eight men and seven women, mean age 24.7 years, with a mean FITA score for the season of 1,211 out of 1,440 and a best of 1,248, each shot six arrows with surface electromyography on the flexor digitorum superficialis and the extensor digitorum of the string arm. The group included the gold and silver medallists from the 1984 Los Angeles Games.

The principle taught is that the string should be let go by relaxing the flexors, without opening the fingers. The flexor behaves as expected in all fifteen: nearly constant activity over the first 900 milliseconds of the window analysed, then a fall in the hundredth of a second before the string leaves, and a decline that continues afterwards. The extensor splits the group in two. Eight archers show a fall there as well, that is, the release by relaxation of the coaching manuals. The other seven show a brief, sharp peak of extensor activity over the two hundred-millisecond intervals before the string leaves: the fingers open actively.

Neither group shoots better than the other. The mean FITA score for the season was 1,209 for the eight in the first pattern and 1,213 for the seven in the second. Each archer repeated his or her own pattern consistently over the six arrows: the coefficient of variation within a person was 16.2% for the flexor and 14.9% for the extensor, while between people it rose to 52.5% and 51.2%. Another unexpected finding: at full draw all fifteen kept both flexor and extensor active, well above resting levels, whereas the extensor was expected to be nearly silent.

One session per archer, in the university biomechanics laboratory. The recording sites were found by palpating the muscles while the archer simulated the shooting position and contracted maximally; the skin was shaved, lightly abraded and cleaned with alcohol, then 16 mm bipolar silver / silver chloride electrodes were placed about 2 centimetres apart, with inter-electrode resistance checked and the preparation repeated if it exceeded 5 kiloohms. The amplifiers filtered below 1 hertz and above 900, with a 60 hertz notch for mains interference; sampling was at 800 hertz.

Before shooting, each archer performed maximal isometric contractions of the flexors and extensors, sampled for two seconds at the peak, which serve as the reference: all shooting values are expressed as a percentage of that maximum. Then, after a rest and a few practice arrows, activity was recorded over five seconds for six shots, with sampling triggered by hand just after full draw was reached, so that the release fell roughly in the middle of the window.

For synchronisation, an electromechanical device on the bow marked two events: the clicker closing against the handle and, through an inertial switch, the acceleration of the bow as the string left. On average 185 milliseconds passed between the two. The analysis covers two seconds, from one second before the release, split into twenty intervals of a hundred milliseconds; the signal was full-wave rectified and integrated in each interval, and for each archer the mean of the six arrows was computed.

Six arrows per archer, in a laboratory, and the paper does not say at what distance or on what target face the shooting took place: the quality of the six shots analysed is not recorded, so whether they were good shots is unknown. The comparison between the two patterns uses FITA scores from the current season, gathered elsewhere and in competition, not the arrows measured here: 1,209 against 1,213 are means of eight and seven people, reported with no test at all. With groups that small, a real difference of a few points would not show up anyway.

Surface electromyography on the forearm also picks up activity from neighbouring muscles. The electrodes over the extensor digitorum sit among other extensors, and the study does not discuss this crosstalk: the burst attributed to the extensor digitorum could come in part from adjacent muscles.

Above all, the argument being tested is about the behaviour of the string, and the string was not measured. The coaching argument is that opening the fingers deflects the string sideways and makes the shot less consistent; what is seen here is only muscle activity, with no measure of lateral movement of the string, the nock or the arrow. The study can say that both patterns exist among very strong archers, not that they produce the same string behaviour. The setting is 1990, with the equipment of the time.

This page matters to anyone who has been told that the release is only a letting go. Among fifteen archers from the United States team, including the two 1984 Olympic medallists, half opened their fingers actively, with a burst of extensor activity two tenths of a second before the string left, and scored the same as the other half. The precept, taken as a general rule, does not describe what the best archers do.

The finding the authors highlight is a different one, and it is worth more: each archer repeated his or her own pattern far more consistently than the fifteen resembled each other. Variability within a person was about a third of the variability between people. What sets a strong archer apart, they suggest, is not which mechanism is used but how faithfully it is reproduced.

One thing the study did not check is worth stating: neither the string nor the arrow was measured, so the question of whether an active opening pushes the string sideways is still open.