Arm strength and shooting in youth: Mohd Saleh 2022

In 31 young archers aged 13 to 18 at the state training centre in Negeri Sembilan, Malaysia, ranging from beginners to the more experienced, the authors measured four qualities and set them against a shooting score. The four measures were arm strength, taken with a bow scale (mean 13.76 kg, range 7.80 to 19.14), endurance, counted as push-ups (mean 34.39, range 13 to 48), balance on one foot (mean 33.19 seconds, range 17 to 49) and the so-called draw force line length, measured on video (mean 121.97 cm). Scores ranged from 18 to 58, with a mean of 39.26.

The correlations with score reported are extremely high: 0.945 for arm strength, 0.906 for balance, 0.896 for push-ups and 0.669 for the draw force line. The physical measures were also strongly linked to each other, up to 0.908 between strength and balance. In the multiple regression only arm strength (p = 0.001) and endurance (p = 0.002) stayed significant, while balance and the draw force line no longer did. The authors conclude that arm strength and endurance are the factors that matter most for performance.

Each archer did three physical tests. Arm strength was measured by drawing the string with maximal effort against an Easton digital bow scale, which reads in pounds (the table reports it in kilograms). Endurance was the number of push-ups and balance the time standing on one leg in the stork test. For the draw force line the authors placed markers on the wrist, elbow and shoulder, filmed the shot from above with a Canon IXUS 105 digital camera and measured the length of the line in Kinovea. The equipment listed is a WINEX recurve bow with Easton ACE arrows.

The links were analysed with Pearson correlation and the relative weight of the four measures with multiple regression. The paper does not explain how the score was obtained: how many arrows, at what distance, on what target face.

The main problem is the sample. Young people aged 13 to 18, from beginners to experienced archers, differ at once in age, growth, strength and years of shooting: the older and more experienced ones are stronger and shoot better, so the correlations may reflect experience and physical development rather than an effect of strength on score. Age, sex and experience were not taken into account in the analysis. With no description of the score (neither distance nor number of arrows), it is also hard to tell what it measures.

Correlations of 0.9 between a one-legged balance test and a shooting score are unusually high for such different measures, and with predictors so closely linked to each other the regression is unstable. The regression table has confused headings, and the authors read the standardised coefficients (0.363 and 0.312) as percentage contributions to performance, which they are not. The text also says the draw force line has no significant relationship with score, while the correlation table shows it as significant at 0.669; the difference lies in the regression, not the correlation. Lastly, "draw force line length" is not a measure with a standard definition, and the journal is a regional outlet.

For anyone who shoots or coaches young archers, the study adds little. It is plausible that stronger and fitter youngsters shoot better, but here that cannot be separated from the fact that they are also older and more experienced, so the data do not show that strengthening the arms earns points, or how many.

The authors' suggestion of using these tests to pick out the most promising youngsters rests on exactly these correlations, and calls for a lot of caution: a weak thirteen-year-old today may simply be a thirteen-year-old who has not finished growing.