Bosu circuit for young archers: Prasetyo 2023 study

Twelve archers aged 14 to 17 from a club in Bantul did eighteen circuit sessions on a Bosu ball and were measured before and after on two things: static balance with the Stork Stand Test, standing on one leg for as long as possible, and a shooting score over 36 arrows at 30 metres. Balance went from a mean of 44.12 to 51.44 seconds, the score from 216.50 to 282.83 out of a maximum of 360. Both differences come out significant on a paired t-test, with t = 7.894 for balance and t = 20.349 for the score.

The individual data are reported one by one and every one of the twelve improved: in the score from a minimum of 41 points to a maximum of 80, in balance from 2.09 to 13 seconds. The mean of the differences is 7.32 seconds and 66.33 points, although the table row meant to report them contains two unrelated numbers, 2.4 and 216.5. The authors conclude that Bosu ball circuit training improves balance and accuracy, and speak of a 30.64% improvement in score, which is the percentage change between the two means.

The circuit has six stations, all of them balance work: standing on both feet and then on one foot, right and left, first on the dome side up and then on the flat base.

The design is a before-and-after on a single group with no control: the twelve club athletes are all those there were, all aged 14 to 17, and the research took place during the pandemic, with temperature checks, masks, hand hygiene and distance between athletes. Parents gave written consent and the university ethics committee approved the protocol.

The treatment is eighteen sessions of Bosu ball circuit training, with the six stations shown in a figure. How long a station lasts, how many times the circuit is repeated, how much rest there is and over how many weeks the eighteen sessions were spread is nowhere stated in the paper.

The shooting test is 36 arrows at 30 metres, totalled. The paper does not say on what face, with what bow, in how many ends or with how much rest. The balance test is the Stork Stand Test on the dominant leg: timing starts when the other foot leaves the ground and stops when balance is lost. Before the t-test the authors ran a Shapiro-Wilk normality check, with values between 0.468 and 0.900, and a Levene homogeneity test; the analysis was done in SPSS 21.

There is no control group, and here that is the limitation that makes the result unusable as evidence of effect. Twelve youngsters aged 14 to 17 training at a club, measured before and after eighteen sessions, improve their score simply by carrying on shooting: 66 points over 36 arrows at 30 metres, that is under two points an arrow, is exactly the progress that comes at that age and level from practice, growth and familiarity with the test. Without a group that did not do the Bosu ball work, nothing can be attributed to the Bosu ball.

The description of the treatment does not allow it to be repeated: there is no station duration, no number of circuits, no rest period, no weekly frequency and no overall span.

The statistics are inconsistent. The paired-test table reports a significance of 0.002 for the score while the text says 0.000; the means row of the first table contains two values that are not means of the differences; the homogeneity test is computed with 1 and 22 degrees of freedom, that is, treating before and after as two independent groups of twelve, which is not the right comparison for paired data; and the text names an independent-samples analysis for a third hypothesis that does not exist in the paper, because there is no second group.

Finally, the study measures static balance on one leg and links it to the score without ever measuring balance during the shot.

The study reports that twelve youngsters did eighteen sessions of balance work on a Bosu ball and that afterwards they stood longer on one leg and shot better. The first result is close to a tautology, because the exercise and the test are the same thing: balance on one foot is trained and balance on one foot is measured. The second cannot be attributed to the exercise, because over the same weeks those youngsters carried on with their archery training and nobody served as a comparison.

That does not make the Bosu ball useless; it makes the study unable to say whether it helps. What can be taken away is that balance work on an unstable surface was carried out with young archers without the score suffering, and that in this group of twelve the gains in balance and in score went in the same direction.

Nothing in the paper says how much balance work is needed, on what surface, at what volume, or whether work on the floor would have produced the same thing. The 30.64% that appears in the discussion is not a measure of an effect: it is the difference between the two mean scores expressed as a percentage.