Video analysis for national archers: Vlasov 2017

Three researchers from the Lviv state university of physical culture describe how they used video analysis with 25 archers of the Ukrainian national team, thirteen men and twelve women, training indoors and outdoors. It is mainly a description of method; the only numerical data are a table of drawing-arm angles, measured on frames filmed from above during the shot.

Two angles are reported for each athlete. The first, at the elbow of the string arm, runs between 35.9 and 45.6 degrees in the men and between 31.7 and 49.7 degrees in the women. The second, formed by the string forearm with the line joining the two shoulders, runs between 116.8 and 146.5 degrees in the men and between 117.9 and 148.4 in the women. These are individual values from athletes ranked as masters of sport and masters of sport of international class, published one by one with no averages, no comparisons and no link to any score.

The rest of the article discusses how film changes the conversation between coach and athlete: immediate review between series for the short-term effect, a collective presentation at the end of the session to fix what has been learnt, and the move from qualitative observation to the measurement of angles.

Filming was done with a single Sony DCR-XR150E digital camera, moved in turn to five positions relative to the shooting line: from above, from behind, from the front, from the right and from the left. As soon as a series ended the raw footage was shown to the athlete and the coach, who commented on the quality of the movement and corrected it on the spot. Later the frames were imported, prepared with the camera's own software and analysed with the Dartfish Connekt package, which allows slow motion, magnification of a detail, freeze frame and the tracing of markers and angles.

All the athletes shot from the classic stance, side on to the target. The angles were traced by hand on the frames, following the method of an earlier paper, and collected in a personal file for each archer along with the footage; from there a presentation was built, shown with a projector and discussed as a group. The article also shows, as an example, an electromyographic recording synchronised with the video, but reports no measurements from it. There are no groups compared, there is no before and after, and the number of attempts analysed per athlete is not stated.

The article tests nothing. There is no group working with video and another going without, there is no before and after measure, there is no score: the statements about the usefulness of video feedback are the authors' reasoning, supported by the literature, not a result of this work.

The table of angles should be taken for what it is too. We are not told at which instant of the shot the frame was taken, how many repetitions lie behind each figure, or what the measurement error might be for an angle traced by hand on an overhead image from an uncalibrated camera. There are no averages, no deviations, no comparisons between men and women or between qualification levels, and no link to performance: two athletes with 31.7 and 49.7 degrees at the elbow may both be excellent, and the article says nothing more. The second measure, the angle between forearm and shoulder line, is defined one way in the text and another in the figure caption, which calls it an angle at the shoulder.

The venue is a regional Ukrainian journal and the text is in Ukrainian, with an English abstract.

What an archer can take away is the table, read for what it shows: across twenty-five athletes on a national team, the elbow angle of the string arm varies by eighteen degrees and the angle with the shoulder line by thirty-one. Even at the highest level, then, there is no correct angle to resemble, and the manuals that name one are describing an average that none of these athletes is obliged to match.

On method the article is a snapshot of how video was used in a national squad in 2017: filming from several sides, immediate review between series, a collective presentation at the end. It does not show that any of this raises scores, and it does not try to. In the registry it counts as a description of practice and as the source of those angle values, not as evidence on the effectiveness of video feedback.