Dehydration and archery accuracy: Cahyo 2023 study

Twenty archers from Banyumas Regency in Central Java shot 36 arrows at 30 metres on two separate days: on the first they drank the amount estimated to meet their needs, on the second 30% less water. Hydration status was judged from urine colour using a self-assessment card (PURI). The authors report a significant difference between the two days in both hydration and shooting accuracy, and conclude that the amount of water drunk affects both.

Yet the paper does not report a single mean score, nor the mean urine colour on either day: the only figures in the results are t statistics and p values. In the table of tests t is 15.215 for dehydration status and 5.2580 for accuracy, while the abstract gives the same two values the other way round. So we do not know by how many points the score changed, and the results do not even state the direction. That the score dropped with less water was the authors' starting hypothesis, which the discussion then treats as settled.

The population was 35 archers in the standard bow division, a national Indonesian category, and the recurve division. Twenty were chosen by purposive sampling: active archers living in the regency, able to shoot at 30 metres, with their own bow and willing to take part. The study took place over two days at the Beji field in Purwokerto. Water needs were worked out with the rule of one millilitre for every kilocalorie of energy requirement; on the first day the archers met that amount in full, on the second they drank 70% of it. Water intake was recorded with a questionnaire, hydration with the PURI card, which matches urine against a colour scale, and accuracy with the score over 36 arrows at 30 metres. The analysis was a paired t test, preceded by tests of normality and homogeneity.

There was a single group with no control, and the order of conditions was the same for everyone: the full water day first, then the reduced one. The introduction describes the PURI card as using a morning urine sample, but the methods do not say when urine was collected on the two days, or whether before or after the shooting.

The weaknesses are basic. Without means and standard deviations there is no way to judge the size of the effect, and the figures that are given do not add up: with 20 paired archers the degrees of freedom would be 19, not the 20 reported; the critical value used (1.72472) is the one for a one-tailed test with 20 degrees of freedom; and the homogeneity test reports degrees of freedom of 1 and 40, which do not match the sample. The conclusion then states that the null hypothesis was accepted, the opposite of what the results say.

The reduced water day was always the second one, so the difference could also come from fatigue, weather or familiarity with the test, and the weather on the two days is not reported. Urine colour is a rough index, read by eye, and drinking 30% less for one day will not necessarily cause meaningful dehydration. The journal is flagged in the registry as one with questionable editorial standards.

For an archer, the study does not show whether drinking less costs points, or how many. The question is a reasonable one, since outdoor shooting means hours in the sun and anyone training in a tropical climate may not drink enough, but this paper gives no usable figures: even the mean score on the two days is missing.

What remains is the observation the authors started from: in that group few archers brought water to training and many drank only during long breaks. That is an observation about behaviour, not a measurement of the effect on accuracy. To find out whether hydration changes the score, we need studies with the conditions in balanced order, less crude measures of hydration and results reported in full.