Turkish archery and final draw: Ödek 2024 study

In traditional Turkish archery many archers stop a little short of full draw, settle the aim on both axes and then complete the draw with a last short pull, which the paper calls the final pull. The study asks how short that last stretch should be, measuring not accuracy but the smoothness of the movement.

Ten traditional archers shot from about a metre and a half in five conditions: stopping at 100, 98, 96, 94 and 92 per cent of their own maximum draw before the last stretch. Three accelerometers, one on the grip and one on the back of each hand, recorded the movement during aiming. From those data comes jerk, the derivative of acceleration, which measures how jagged a movement is, in the logarithmic dimensionless form that makes it independent of duration and amplitude; the closer the value to zero, the smoother the movement.

Jerk changes markedly with the starting point of the final pull, at all three sensor positions: repeated measures analysis of variance gives large effects, with partial eta squared of 0.98 for the bow, 0.99 for the bow hand and 0.92 for the drawing hand. The lowest values fall at 98 and 96 per cent. The bow hand and the bow follow the same pattern: at 98 and 96 per cent they do better than the shot with no final pull, at 94 and 92 per cent worse. The drawing hand does not separate the shot without a final pull from 98 and 96 per cent, while at 94 and above all 92 per cent it clearly worsens. The absolute differences, though, are very small, between 0.00 and 0.05 index units.

The length of the final stretch in centimetres is 1.57 at 98 per cent, 3.21 at 96, 4.70 at 94 and 6.27 at 92. Lastly, the jerk of the bow is not explained by the bow hand or the drawing hand taken one at a time, while the two together explain it well in all five conditions, with coefficients of determination between 0.79 and 0.91.

The ten participants averaged 32.4 years of age and 6.2 years of practice, six men and four women, and used the final pull in both competition and training; they trained three days a week for an hour and a half to two hours. The paper describes them as archers with national and international competition experience, and lists the exclusion criteria: no condition related to tremor, no injury or surgery in the previous six months, no medication, no other scheduled physical activity, and no stimulants or sedatives in the preceding twelve hours. The bows were their own traditional composites, with draw weights the paper gives as between 38 and 55 pounds and averaging 42.25 with a standard deviation of 2.09.

Acceleration was collected at one hundred samples a second with three three-axis accelerometers built into activity monitors, placed on the upper front of the grip and on the back of the third and fourth metacarpals of each hand. A camera at one hundred frames per second, on a tripod 160 centimetres from the ground on the drawing-hand side and perpendicular to the arrow flight plane, filmed the whole shot. Synchronisation was done by fixing the three monitors in a box and dropping it from about 30 centimetres in front of the camera, using the impact as a common reference.

Maximum draw was defined as the mean of three shots without a final pull, marking the arrow shaft level with the back of the grip and measuring the distance to the base of the nock. Marks at 98, 96, 94 and 92 per cent were made on the same shaft, each carrying a one millimetre rubber ring, because in early attempts without rings the archers could not see the marks and missed the intended distances.

After five warm-up shots each archer took fifteen shots, three per condition, from about a metre and a half from the target, in order from the shortest stretch to the longest. The instructions fixed the timings: reach the position in three seconds, align for three seconds, complete the draw in two seconds, wait one second at full draw and let go. One minute of seated rest separated the shots, and during the break the shot just taken was reviewed on a computer: four shots across the whole study were repeated for not meeting the conditions. The analysed segment runs from the moment the prescribed draw is reached to the release. Acceleration was filtered between 2 and 15 hertz, since physiological hand tremor lies between 8 and 12, and jerk was computed on the three axes and then averaged. The comparison is a repeated measures analysis of variance with Bonferroni correction, bringing the threshold to 0.005, plus multiple linear regression explaining the jerk of the bow from that of the two hands. Scores were not collected: the archers were only asked to shoot as close as possible to a spot of their own choosing.

The largest limitation is the distance. The shots were taken from about a metre and a half from the target, so nobody measured where the arrows went, and the author says as much: a study looking at score differences across final pull lengths remains to be done. Everything here concerns the smoothness of the hand and bow movement, and the step from there to a score is an inference leaning on other studies.

The sample is ten people, which the author gives as the main limitation, explaining that it was hard to assemble a homogeneous group of traditional archers using that technique with similar experience. Ten people and three shots per condition means fifteen shots each: a narrow base for a repeated measures analysis with five levels.

The measured differences are tiny. In the table of pairwise comparisons the index gaps run from 0.00 to 0.05, while the F values reach enormous figures, in one case above twelve thousand: numbers like those arise when variability between shots within the same archer is extremely low, and they say the effect is repeatable rather than large. The regression results also carry printing inconsistencies: one trial reports F with two and seven degrees of freedom equal to 19.83 with p of 0.048, which does not follow, and in another a t value of 3.141 is given as non-significant with p of 0.196. The equipment figures do not add up either: a mean draw weight of 42.25 with a standard deviation of 2.09 cannot sit with a stated range of 38 to 55 pounds across ten bows.

The measurements that would explain the result are missing. There is no electromyography, and the author lists this among the limitations: tremor and jerk arise from muscle activity, which was not recorded here. The aiming phase was not split into a static and a moving part, so in shots with a long final pull the jerk of the drawing hand also contains the intended movement rather than tremor alone. The order of conditions was fixed, from the shortest stretch to the longest, so fatigue and familiarity with the series overlap with the effect. Finally the bow is a traditional composite, without stabilisers or dampers, and the author notes that an archer's error therefore transfers more directly: the same design on an Olympic recurve might give a different result. The journal is a Turkish national venue.

The study describes something traditional Turkish archers already do and puts numbers on it. Those who stop very little short of maximum draw, around one to three centimetres, move hand and bow more smoothly than those who stop six centimetres short, and also than those who do not stop at all. The reason offered is twofold: holding full draw for six seconds lets tremor in the bow hand grow, while a long final stretch adds the movement itself to the drawing hand, and the best balance lies in between.

It should be said plainly that this is not a measurement of score. From a metre and a half away there is no telling whether the arrow lands closer to the centre, and the link between jagged movement and points remains a hypothesis borrowed from other work. The differences found are also small on the scale of the index used, even if they repeat within each archer.

One thing the paper measures usefully, and independently of the final pull, is this: the movement of the bow while aiming is explained by neither hand on its own, while the two together account for roughly eighty to ninety per cent of it. In practice the bow is steady or it is not according to how the two hands behave together, and looking at one of them is not enough to work out where the movement comes from.