Multifactorial archery analysis: Squadrone 1994

Two researchers from the Politecnico di Milano and the Institute of Sport Science in Rome measured movement, foot pressure and muscle activity together in 12 archers from the Italian federation: 5 at high level, with FITA scores above 1,300, and 7 at intermediate level, between 1,180 and 1,300. Each shot 20 arrows.

The main result is descriptive. Each archer repeated an electromyographic profile so consistent from shot to shot that any one of them could stand for all the others, but across archers no common profile emerged: each had their own. The normalised peak activity values in the paper's table range, for example, from 23 to 58 for the finger flexors and from 36 to 88 for biceps. The way of reaching full draw was personal too: some raised the bow and then brought the drawing arm back, while others moved both arms at once in opposite directions.

The differences the authors link to skill level concern the relative length of the phases, the stability of the bow and arm, and biceps activation, which was lower in the better archers (between 36 and 73, against 46 and 88). FITA score correlated with the mean length of aiming (r = -0.72) and with lateral bow sway (r = -0.67): those who aimed for less time and moved the bow less had higher scores. Centre of pressure movement on the force plate, on the other hand, was not enough to tell the two levels apart.

The archers shot from 12 metres from the target, in a laboratory set-up. The ELITE system tracked 23 reflective markers at 100 frames per second, placed on the head, shoulders, elbows, wrists, hands, iliac crests, knees, ankles and feet, plus three on the spine and three on the bow. A Kistler force plate recorded ground forces and centre of pressure movement at 1,000 Hz. Surface electromyography, also at 1,000 Hz, covered the finger flexors and biceps of the drawing arm and two portions of the trapezius on each side; the signal was rectified, integrated over 100 ms intervals and expressed relative to a maximal isometric contraction. An electrical device fitted to the bow marked the clicker closing, the release and the arrow leaving the string, so that every measurement could be aligned with the phases of the shot.

This is a four-page conference contribution: it describes the method carefully, but of the results it reports only the table of muscle peaks, two correlation coefficients and a comparison between two archers. Phase durations, bow sway values and any statistical test between the groups are missing, and it is not explained how lateral sway was measured. The two correlations are calculated on 12 people, using each archer's FITA score rather than the 20 arrows shot in the test, whose scores the paper does not report.

With cameras at 100 Hz, as the authors acknowledge, the release lasts about 3 frames and cannot be analysed. Shooting from 12 metres among cameras and a force plate is also different from shooting at 70 metres outdoors. The explanation offered for the archer with a tilted shoulder line and very active biceps, linked to an attempt to keep the bow shoulder down, is the authors' hypothesis about a single archer.

The most solid message for anyone who shoots is that repeatability is individual: each archer had a muscle pattern of their own, very stable from shot to shot, and two high-level archers with similar scores could have very different posture and activation. These data give no basis for copying a champion's muscle sequence.

The link between FITA score, shorter aiming and a steadier bow points the way many coaches would expect, but it comes from 12 archers and two correlations without the underlying data. The same goes for the lower biceps activity in the better archers: it fits the idea of a draw carried more by the back than by the arm, but the study does not measure that directly.