Expert and novice archers compared: Musa 2018 study

Four Malaysian archers were compared in pairs, wearing sensors, while shooting at 50 metres. The first pair were two young women: one who had just won gold at the Malaysian national games (SUKMA), aged 20 with eight years of shooting, and one without a medal, aged 18 with six years. The second pair were two men: an experienced archer of 25, with twelve years of shooting and many medals, and a novice of 20 with one year.

The results are charts only, described in words without figures or statistics. According to the authors, the medallist and the experienced archer showed more activity in the finger extensor of the bow arm, less activity in the finger flexor of the drawing hand, a steadier bow, less pelvic sway and a lower heart rate, together with higher and more consistent scores.

The equipment was four Shimmer sensors: an accelerometer fixed to the pelvis for body sway, a sensor held by a glove on the bow hand for bow movement, EMG electrodes on the finger extensor of the left arm and the superficial finger flexor of the right, and a heart rate sensor at the wrist. Data were sent over Bluetooth to an Android phone at 51.2 samples per second. In the first pair each archer shot three practice arrows and one end of six; for the second the paper says only that the protocol was similar. The observations cover stance, aiming and release. Bow type, draw weight and arrows are not reported.

With one archer per level the comparison is between people, not between levels: the difference may come from body build (the experienced archer weighed 97 kg, the novice 76), the bow, the draw weight or simply that day. There are no figures, no averages over several arrows and no tests. Surface EMG is usually recorded at around a thousand samples per second; at 51.2 it shows the general shape at best, and the signal is not normalised to each muscle's maximal contraction. The link between heart rate and score is drawn from six arrows.

Some claims rest on references about other subjects: the relaxation of the flexor is credited to a paper on an Android platform for health applications, and bow movement to a study of walking. The journal has questionable editorial standards.

The study shows what can be recorded with four wearable sensors during the shot, not what separates a strong archer from a weaker one. The trends it describes, less body and bow movement and a more relaxed drawing hand in the better archers, point the same way as other studies with larger samples, but this paper does not measure them in a way that can be weighed.

The same group used the same sensors on 32 young archers in a 2017 paper, which at least reports figures and tests. For anyone wondering whether a wearable sensor could help their own training, this gives an idea of what can be looked at, not a result.