The expert archer's shoulder: Kępczyński 2021

This short communication compares shoulder movement in 15 archers from the Polish national team with that of 15 people holding a bow for the first time, across the whole sequence: raising the bow, drawing, releasing and lowering the bow. The authors report shoulder moments in newton metres per kilogram of body weight and the course of the joint angles.

In the archers the mean moments were 0.005 and -0.073 Nm/kg for flexion and extension, 0.092 and 0.027 for abduction and adduction, -0.008 and -0.035 for internal and external rotation; in the novices 0.003 and -0.024, 0.085 and 0.051, -0.016 and -0.029. The archers raised the bow by abduction in the frontal plane with marked external rotation, from about 45 degrees of internal rotation to 100 degrees of external rotation during the shot; the novices turned the trunk towards the bow and relied more on flexion than on rotation. Differences between one archer and another were small, those between novices very large.

The authors conclude that the way experienced archers bring the shoulder into position loads the joint structures and may explain how common shoulder complaints are in the sport.

Measurements were taken in the main laboratory of the Warsaw University of Physical Education, using a VICON motion capture system with reflective markers placed according to the Plug-in Gait scheme. From the marker positions the authors derived shoulder angles and moments about three axes. The archers averaged 23.47 years of age and 11.07 years of shooting, the novices 27.75 years of age; body weight and height were similar.

The paper does not say which shoulder was analysed, how many trials each person performed, which bow and draw weight were used, or whether anyone shot at a target. Time in the charts is expressed in "seconds" up to 300, a duration that makes no sense for a single shot: most likely these are frames or a normalised scale, but the text does not say. There is no statistical analysis.

These are two pages without statistics: the moments are means without standard deviations, and the differences between groups are not tested at all. The values are very small, a few hundredths of a newton metre per kilogram, and there is no explanation of how they were calculated for a largely static action such as holding at full draw. The age standard deviations are identical in the two groups (9.25), which suggests a transcription error. Comparing archers with people who have never shot mainly measures the difference between those who can shoot and those who cannot, not a risk factor.

The step from shoulder rotation to injury is the authors' reasoning, not a finding: no participant was assessed for pain or injury. The idea that the novices' movement is easier on the shoulder does not follow from this comparison either, since a novice does not repeat that movement over thousands of arrows, and the draw weight used is not reported. The journal has questionable editorial standards.

For an archer the study changes nothing concrete. It describes in qualitative terms something every coach sees: the experienced archer raises the bow and sets the shoulder with a repeatable movement, while the novice improvises, differently each time. The figures are too few and too poorly documented to say how much one technique loads the shoulder compared with another.

The authors' claim that poor technique and an ill-chosen bow cause shoulder problems does not come from these data. The registry holds studies on archers' shoulders with measures of pain and function; this one remains a description of the movement in 30 people.