Arm strength test for archers: Prasetyo 2022 study

The study builds a device for measuring arm strength in kilograms and holding time in seconds, in a movement close to that of the shot. It is called the Holding Bow Digitec Test, and it mounts a 24-inch wooden riser on a compression spring calibrated to 80 kilograms, with a load sensor, an ATmega32 microcontroller, a two-line OLED display, memory for 200 measurements and a USB port for transferring data to a computer.

The check consists of comparing the device with the manual version of the same test on 33 adult archers, 18 men and 15 women, students aged 20 to 23. On strength the digital device gives a maximum of 25 kilograms, a minimum of 14 and a mean of 18.18; the manual version gives 25.4, 14.5 and 18.54. On holding time the digital device gives a maximum of 24 seconds, a minimum of 15 and a mean of 20.34; the manual version gives 24.4, 15.2 and 20.48. The correlation between the two measures is 0.939 for strength and 0.974 for holding time.

On repeatability, two successive trials with the digital device give a mean of 17.94 kilograms on strength in both (standard deviations 2.79 and 3.07) and 19.94 and 19.91 seconds on holding time. Before reaching this point the device went through assessment by three experts, two trials on groups of archers and two revisions: the tension spring became a compression spring, and the display, which faced the archer, was turned to face forward.

The work follows Borg and Gall's ten-step research and development model, which the authors group into a preliminary phase and a development phase. The preliminary phase begins with a fourteen-question survey sent in June 2017 to twelve coaches from Indonesian national and provincial centres, some with international qualifications: ten respond very favourably to the idea of a dedicated device, two favourably. The coaches report that the tests in use (push-and-pull dynamometer, push-ups, one-arm holds, and the bow holding test done by drawing the bow and counting the seconds) are neither specific nor standardised, because the draw weight of the bow used for the test varies from centre to centre.

In the development phase the device is designed, built with the help of an electronics technician and assessed by three experts, one in subject matter, one in electronics and one in media, each on a separate four-point rating sheet. A small-scale trial with 10 athletes from the Yogyakarta university club follows, then a wider trial with archers from the same club and from the Klaten provincial association. The final measurements took place at the Yogyakarta student training centre, with data collection spread between March 2018 and July 2019.

The analysis uses percentages for the questionnaires, Aiken's V for content validity, Pearson correlation between the digital and the manual measure for concurrent validity, and a test-retest with the same correlation for reliability, with homogeneity and normality checks beforehand.

The test protocol is not described: there is no record of what resistance the archer works against, how far the draw is taken, how the end of the hold is defined, how much rest there is between attempts, or how much time elapsed between the two trials of the test-retest.

Concurrent validity here is a comparison between the device and the manual version of the same exercise, not against an external criterion. It says that two ways of measuring the same hold agree, not that the hold measures something that matters for shooting: no arrow was shot and no score was collected. Correlation also answers a different question from agreement between two instruments, since two measures can rise and fall together while differing systematically; the means here are close, which is reassuring, but the appropriate comparison, the mean difference with its limits, is never made.

The sample is 33 adult archers from two clubs, the authors state the device suits adults only, and reference norms are missing, which the authors themselves leave to future work. Alongside the limits they list (measurements in different places and at different times, athletes in varying condition, a restricted sample), calibration of the sensor, drift over time and the instrument's stated error are also absent.

Many of the paper's numbers do not add up. In the text about the electronics expert's ratings the two values are swapped relative to the table (57.15 and 42.85%), and the media expert's table shows 42.85% where the counts give 52.95%. The two homogeneity tables carry the same title. In the correlation section a significance value of 0.330 appears that comes from no calculation shown, and the threshold is written several times as 0.005 instead of 0.05. The conclusion speaks of reliability calculated with Cronbach's alpha, but no alpha is reported in this paper, and the method section declared a test-retest. Finally, the discussion states that the device produces an increase in archers' arm strength and endurance: no training was carried out in this study, and the sentence has no support in the data.

The same sample and the same data also appear in the same authors' conference paper on the validity and reliability of the device, which is already linked to this record.

What the device adds over a timed hold with the bow is standardisation: the resistance no longer depends on the draw weight of whatever bow the club happens to own, strength comes out in kilograms, and the data stay in memory. That was the problem the coaches surveyed had flagged, and on that point the study offers an answer.

What it does not offer is a reason to believe the resulting number matters. The study never relates the kilograms or the seconds to accuracy, to score, or to the capacity to get through a full competition, and it does not say how much a value has to change before the change exceeds the noise of the measurement. An archer counting the seconds at full draw is measuring the same thing more roughly; this device measures it more tidily, and for now that is all. For a reader of the registry, the reason this record exists is a different one: the Holding Bow Digitec Test is the instrument other studies on Indonesian archers use to measure arm endurance, and it is worth knowing what it rests on.