Shot consistency in recurve: Kim 2023 study

Nine world-class Korean recurve archers, all women with more than ten years of shooting and at least one international win, shot 40 arrows at 8 metres indoors: 20 in the usual way, releasing when the clicker fell, and 20 without it, deciding for themselves when to release. Shots in the two conditions were taken in random order.

Without the clicker the draw was shorter (p=0.012, Cohen's d 1.07) and aiming more consistent: the precision index, the mean distance between the point aimed at on each shot and the average aiming point, was smaller (p=0.036, d=0.84). Draw length did not differ between conditions. On the force plates, the speed of the centre of pressure rose sharply in the last 50 milliseconds before release, a sign of an anticipatory postural adjustment; in the forward-backward direction this rise was steeper with the clicker than without (p=0.013), while sideways it did not change. Without the clicker, the archers with the smallest forward-backward adjustment were also those with the most consistent aim (r=0.75, p=0.019); with the clicker, and in the sideways direction, the correlation was not significant. Activity in the lower leg muscles (tibialis anterior and soleus) and their co-contraction did not differ between conditions.

The authors work at the Korea Institute of Sport Science and Seoul National University, and this study takes an earlier experiment of theirs, run with a frame that simulated a bow and with participants who were not professional archers, into real archery. The archers, with a mean age of 25.9, shot their own bows at the centre of a target, with a compulsory 20-second rest between shots and no instructions about posture. Six Qualisys infrared cameras at 100 Hz tracked markers on the limbs, clicker, stabiliser and drawing hand; two Kistler force plates recorded the centre of pressure, and wireless EMG recorded tibialis anterior and soleus in both legs.

The start of the draw was taken as the moment the bow, having been raised, began to come down; release was the first sideways jolt of the limb. The aiming point at release was calculated from the orientation of the stabiliser and the distance to the target, not from where the arrow landed. Posture and muscle activity were analysed over the 200 milliseconds before release. The two conditions were compared with paired t-tests and repeated-measures analyses of variance.

The authors name the main limitation themselves: 8 metres indoors is far from competition distances, and precision is calculated from the orientation of the bow at release, not from arrows on the target face. An index based on the stabiliser cannot see the variations in draw length and release that move the arrow up and down, which is exactly what the clicker is there to control. The paper reports that mean draw length did not change, but not how much it varied from shot to shot without the clicker.

The sample is nine archers, all women and all Korean, and the correlation between postural adjustment and precision rests on nine points, one per archer: a single outlier can shift it a great deal. Values for the precision index and draw duration appear only in charts. Shooting 20 arrows without a clicker in a laboratory is not the same as doing it in competition, and the study says nothing about what would happen over time. Lastly, the link between postural adjustment and aiming consistency is a correlation, and the explanation tying it to clicker reaction time is the authors' interpretation.

The authors do not say the clicker should go: they write that their results do not mean shooting without one is better, since the clicker takes one of many things off the archer's mind. What they propose is different: training the archer to anticipate the clicker falling rather than reacting to a signal that comes as a surprise, given that in this experiment waiting for the clicker lengthened the draw and made the postural adjustment in the last 50 milliseconds more abrupt.

For anyone who shoots, this is an interesting pointer to how the release is reached, but it was observed at 8 metres, in nine outstanding archers, with precision measured on the bow rather than on the target. It does not say whether the same holds for archers at lower levels, or whether training built on the idea changes scores.